The ontogeny and evolution of Kozłowskiella (Pribyl) (Ostracoda)

A C T A P A L A E O N T O L O G I C A P O L O N I C A

Vo l. 11/ I 9 5 8

FRANCISZEK ADAMCZAK

No.2

THE ONTOGENY AND EVOLUTION OF KOZLOWSKIELLA (PRIBYL) (OSTRACODA)

Abstract. -

This p a pe r deal s with resrult s of in ve s tiga tio n s on genus

Kozlowsk ieZla

( P riby l) fr om Midd le Devon ian b ed s in localities Wydryszow, Grzegorzowice and Ska ly (Hol y Cr os s M ountains, P oland). The assi gnment of the mentioned genus to

Ulrichia

Jones as its sub genus - as adv ocated b y Pribyl - is here r ej ected . On t o- , gen y and v a riab ili ty of d escr ibed for m s, in cluding some new species, a re analy zed.

INTRODUCTION

This paper prese nts information ob tain ed during r esearches on

<os tr acod s of the ge nu s K ozl owskiella (Pribyl) from the Middle Devonian of the Holy Cross Mts.

'I'h e co pio us m at eri al , on which the in v estigations a re ba sed , has been collect ed by th e wr it er in loc alities of Wydrysz6w, Grzegorzowice and S kaly in 1955 and 1956. No os t racod descriptions have thus far been publis he d f rom th e first t wo of th ese loc alities a nd th e material now co ll ected ther e sh ed s so m e li ght on th e evolu t ion of the Middl e Devonian gen us K oz low sk iella (Pribyl) . The ontogeny and va r iations of the her e . d escr i bed species have been st udied in detail, h enc e it has been possible to det ermin e t he mu tu al relations between t hese for ms as well as t he mo di fications which th ey ex pe r ience in the co urse of ontogeny.

. The relation of Ko zlo wskiella to Ul richia Jones has a lso been ana lyzed.

Accord ing to A. Pribyl (1953) K ozl ow ski ella is a subgenu s of U lrichia.

The present writer, how ever , has a r r ive d at the concl usion that Ko zlow- ski ella should be se pa ra t ed into a distinct genus and , in regard to its

.d imor phism , perhaps similar to the cru minal one, probably placed within

the fa m ily Beyrichiidae.

Th e a ut hor h er e expresses his warmest gratit ude to Prof. Dr . R. Koz- lowsk i for the va lua ble sug gestion s and criticism ge ne rous ly offered du ri ng t he preparation of the paper. Many t hanks are also due to Dr.

Z . Ki elan fo r r eadi ng t he m anusc ri p t an d to Mrs . J . Humnicka for trans-

lating th e text into E nglish , as we ll as to M iss L. Luszczewska for the

pai ns t aken in do in g the photographs .

76

^{FRANCISZEK ADAl\lCZAK}

Cordial t ha nks a re also due to Dr. E . N . Polenova of t he VNIGRI In stitut e in L en ingr ad , for her gift of com parative m aterial and for fa- cilities offered to inspect t he r ich ost r acod collection f rom Devonian bed s of the USSR during t he writer's visit to Leningrad in 1957.

Th e present work is the second in a se r ies of papers to be d evoted to Devonian ostracods from the Ho ly Cross Mts .'

TERMINOLOGY

The terms used here for th e various mor phological elements of t he carapace are those introd uced by 1. Hessl and (1949), R. V . Kessling (1951), A . Martinsson (1956) and V. J a anusson (1957). F urthermore, the r e are- also some terms introduced into literature by G. Henn ingsmoen (1954) , and accepted by t h e present writer.

4

Fig.

1.

Ornamental details of carapace surface; S l anterior sul- cus, L2 median lobe, S2 median sul cus , L3 posterior lobe,

t

tuber-

cles, vr velar ri dge.

Fig. 2. Transverse section of carapace of fe male K .

pr aetuber - cutata

n . sp., simplified ;

1

ve lar ri dge, 2 adrnarginal r idge, 3 sub - v ela r area, 4 do rsa l p li ca, 5 hi n ge

gr oove , 6 mu scle scar .

A n ad ditional term is t hat of " dark lines" used to designate peculiar m icroscopic struct ur e elements of the ca rapace which have been investig- ated in t hin sections of r epr esen tatives o f genus Ko zlowskiella (Pribyl).

1

The firs t p aper : F. Adamcza k ,

Potyzygia

Giirich, a n Ostracod genus from the

Givetia n of th e H oly Cross Mt s, -

Act a Pa laeont,

P ol., vol. T, No.1 , pp. 35-48.

ONTOGENY AND EVOLUTION OF KOZLO lV SKIELL.4

77

These ar e dark lines v ert ica l to the surface of t he carapace and arra nged to fo rm distinct r eticu lation of th e carapace.

In what the margi nal va lve elements are conc erned it ha s be en asce r tained t hat t he so-called ad marginal ridge is grad ua lly ' t ran sformed into admarginal t ubercles. Both th ese elem ents are, th erefore, ho mo logo us and m ay be of some significance for the compari son of re lated for ms (fig . 1- 4).

MATERIAL AND METHODS O F WORK

The mat erial studied in th e pres en t pa pe r has been yielded by marly-argillaceou s beds of Middle D evonian age in the Lysog6ry region of the Holy Cross Mt s. Samples were t ak en in th e localities of Wydrysz6w, Grzegorzowice and Skaly. Withi n the two first n amed localities the occurrence is noted .of fairl y comp lete Lo wer Cou vini an (Eifelian) series.

In either of t hese localities, how ev er , the Co uvin ian s eries are represented by a slightly different facial typ e and, mo st likely , t hey do not belong

Fig. 3. - K.

kozlowskii

(Pribyl), right valve, inside view (d ia gram so mew hat schematic); 1 hi n ge groove,

2 lis t, 3 ve lar ridge, 4 ad m a rgin al tu be rcles.

to exactly th e sa m e st ra tig raphic horizon. It r at he r seems that the Wy-

drysz6w complex is olde r than that of Grzegorzowice. That this is so

may, to a certain ex tent, be infe r r ed fr om th e quantitative sh ar e of the

78

^{FRANCISZEK ADAM C ZAK}

three repre sentatives of g enus K c ziouiskietla. (Pribyl) yielded by t h e two successions.

The state of preservation 00£ the ostr acod fauna LS not everywhere uniform. On the whol e quite a numb er of the Wydryszow zones display

F ig. 4. - Lon gi tudin a l section of right valve of K .

pr ae t u be rc u l a t a

n . sp, (sche - m a tic diagram) ; 1 por e ca n a ls , 2 dark lin e , 3 muscle scar , 4 ad marginal r id ge,

S vela r rid ge.

populat ions in excellent st at e of preserva tio n, con t ai ning a fa ir ab und anc e of representatives of all, ev en th e yo ungest ontogenetic st ages . Only wit hin t he basal parts, t he va lves are scarc e and damaged so th at i t w a s poss ible to coll ect b ut som e few specimens. The G r zegorzowi ce m at erial is l ess complet e , since l ar ge pa rts of the se ct ion her e a re covered by loess . Ostracod va lves from the basal po rtions of that section h av e not b een stu die d at all in vi ew of their un sati sf act ory state of p reservation. The upper portions of the Grzegorzowice succession h ave yielded a fa irly r ich fa unal assemblage containing ot her fossil s b esid es ostracods. How- ev er , w hen comparing the popu la t ions, coll ected f rom these two sections , t he assemb lag e f ro m Wyd rysz6w is pronouncedly the richer one.

With in both th ese sections, the occ urrence is noted , besides ostra-

cods, also of b r yozoan s, brach iopo ds, trilobites and crinoids. Some for-

am inife rs have been fo un d to o.

ONTOGENY AN D EVOLUTION OF KOZ L O W SKI E L LA 79

Material of Givetian age h as been yielded by one horizon only, i. e.

by the so -c all ed brachiopod shales of the Skaly series. The presence of representatives of genus K ozlo w skiella (P ribyl) has not t h us far been r ecorded from eit he r th e lower or th e upp er parts of the Skaly section.

Ostracod va lves collected from t he brachiopod shales ar e in an excellent st a te of preservation; they include t he youngest instars too .

An a nalysis , of this mat erial h as shown that we a r e here dealing with speci es Ko zlowskiella ko zl ow sk ii (P ribyl 1953), closelly allied wit h the Couvinian forms.

In t he Skaly m aterial the majorit y of sp ecimens are adult forms, while in t hat from the Wydryszow section immature valves predominate.

A total of appro x . 3000 valves of genus K oz lowskiella, corresponding to var io us ins tars, ha s been coll ected fro m material sampled in the three mentioned localities .

The copio us Wydry szow m at erial has y ielded some spe cimen s, wi th carapac es of the yo unger i nstar still attached to th em . These sp ecimens no doubt represen t the momen t of moulting an d, unqu estionably, such immat ure forms m ay be regarde d as necroco enosis . The isol ated val ves , on t h e other ha nd, in the wr iter's opinion, r epresent mostly moulting mat erial, in this particular cas e - a pseudocoe no sis . Such observations can hav e som e sign ifi can ce for the st udy of po pulations.

Sam ples tak en fr om m arl y and marl y-argillaceous rocks were mac erat ed with Gl aub er's sa lt. Th e washing r esiduum w as next examined under binocular mi croscope, us ing a sim plified Tri eb el tray to pick out th e microfossils.

Measurem en ts we re t aken by m eans of an ocula r m icrom et er under X 30 magnifica tion . To car ry out t he m easurem ent the va lves w ere pl aced on a glas s pl ate coate d with a thin wax l ay er en ablin g a convenient or ient at ion of the 'valv es. T his is a time-sparing m ethod, as several hundred specimens may be p laced for com par ison on on e glass plate.

Some ' va lves w er e t r eat ed by h y d rofluor ic acid (1. G. Sohn, 1956;

Ch. F. Up shaw and alies , 1957). The fl uor id izatio n m ethod has produced good results . Many ornam en t ation and st r uct ure d etails m ay thus be st udied in transm itted li ght withou t m utilating the va lves as in t he case of thin se ctions (fig. 5). 10% hydrofluoric a cid wa s used by the writer.

Det ached va lves w er e immersed in a wax ves sel fo r a bou t fift een minutes

and then t ak en o ut and washed with wat er . Car ap ac es, after treat m ent

by acid , in most cases proved to be damag ed, crack ed, and unsuitable for

study i n transmitt ed light; w hereas single valves studied in trans mitted

light , und er a X 600 m agnif ica tion, r evealed even the m ost minute struc-

t ural d et ail s.

80

^{FRANCISZEK ADAMCZAK}

No d iff icu lties w ere enco u n te red during segregation of copious material wi th immature forms. Kesling 's method (1953c), war r a ntin g great eco no my of -t im e, is a m ost su it ab le one fo r t h is purpose.

Fig. 5. - K.

praet ubercula t a

n. sp., righ t va lve, fl uor -

. id ized; X 40.

OBSERVATIONS ON THE VAR IABI LI T Y IN GENUS KOZLOWSK I EL LA (P RIBY L )

The three new Couvini a n s pecies di fferentiated by the writer within genus K ozl ow skiella (P ri byl) and t hat d escribed from the Skaly (Givetian) by A. Pribyl (1953) are geneti ca ll y very closely interallied. The fo rms from the Couvinia n con s titut e fa irly w ell diff erentiated populations displaying two esse n tia l evol utiona ry trends.

The first trend is r epresented by K ozl ow skiella sim ili s n .sp . This species is with a prominent 1.3 and with elo n gated valves.

T he other trend is r epres ented by Kozlowskiella tuberculata n. sp., dist inguished by a broad s u bvela r area a nd by the presence of two tuberc- les on L3 . I n ad dition, r epres entatives of th is species a re of a size decided- l y gre a t er t ha n that of the remaining f orms. A ssoci a t ed wi th the same t ren d of evol ution is the third species, namely K ozl ow sk iella pra etuber- culata n. sp. , charact erized by a te n de ncy to prod uce t ub ercl es on L3 (fig. 6).

K. praetubercul at a n. sp. will be h ere discussed fi rst, since it is

apparently tha t fro m w hich t he other fo r m s have d erived. Within Lower

Couvinian rocks r epresen t ativ es of this speci es predominate in the ma-

jority of samples . On the evidence of analyzed material , yielded by

successiv e horizons, a constant tend en cy to increase size ha s been ascer-

ONTOGENY AND EVOLUTION OF KOZLOWSKIEL LA 81

c

B

A

/

1

^"

:

^'

· .,

)

Fig. 6. - Mutual relationship between species of ge n us

Kozl ow sk ie lla

(Pribyl) in Middle De v o ni an layers of the H o ly Cr oss M ts. ;

A

K.

praetu berculata

n . sp., B K.

tuber- cu /at a

n . sp. , C

K. kozlowskii

(Prib y l). D

K. simi/is

n. sp .

(le ft v a lv e s ).

tained as ta k ing pla ce here. Adult fo rm s within the b asal par ts of th e se ct ion as a rule do not ex ceed 1.9 mm in length. Within upper portion s of the succession t he ir l ength r anges f rom 1.8 to 2.15 mm, while forms with a length from 1.95 to 2.4 mm hav e been found with in top horizons (fig. 7A , B) . The outline of carapace is not subject to any gre at er varia- tion s. In particular in sta rs the l ength/height ratio (fig. 8a) shows a mea n figure of 1.33 , indicating a nearly subova l shape of all t hese carapaces . Immature specimens do not display any importan t va r ia tions . Differenc es in , respect t o the quantitative per cent participation o f Ko zlowskiella praetubercula ta n . sp., as compa r ed aga inst t hose of ot her here described spec ies, are ob viously importan t. K. praetub ercula ta .n . sp . · (fig. 9)

IS

Acta Palaeontologlca Polon lca - vol. Ill/2 ₆

F ig. 7. -

A

Size of com p le te adult carapaces a nd of single left valv es in K.

prae- tubercu~ata

n. sp, from three different Wydrysz6w horizons. Length of valves in mm - on ordinate, samples from succes sive la yers - on ab sc issa.

B

Per cen t figures of adult forms of K.

praetuberculata

in the faun al composition of three different Wydrysz6w horizons. Numbers of lef t valv es and of com plete carapaces

in per cen t figures - on ordinate, size in mm - on abscissa .

Fig. 8. - Length/height r atio of carapace in va ri ous instars ;

a K. pTaetubeTcu~ata

n. sp., b K.

tubeTcu~ata

n. sp., c K.

kozlowskii (Pribyl), d K. si-

mHis

n. sp,

distinctly predominant in samples collected from the lower layers of the Wydryszow section. In the Grzegorzowice section (fig. 10), which has yielded relatively less abundant material (approx . 50 speci- m ens) , the particip ation of this species is smaller. The predominant form is here K. si- m i lis n. sp. which, on the average, represents 49.8 per cen t of the total ' population. K. tu- bercula ta n. s p. makes up only 4 per cent in samples from t he Grzegorwwice s ection, but it is an interesting form owing to its inter- mediate position between K. praeturbercu- lata n. sp. and K. ko zlowskii from the Give- ti a n . These three species are characterized by a constant ontogenetic trend to produce a broad subvelar area (fig. 11, 12), a promi- nent L3 and admarginal tubercles. A branch line in the evolution of this species is re- presented by K. similis n. sp. (fig. 6).

The numer ical share of K . tuoerculata n . sp, within the basal parts of the W ydry- szow section does not exceed 10 per cent (fig. 9) of the total material in this sample.

16

l/H

15 13

14

a bdc

9

,

I

^I

, ,,

I

ⁱ

I

.,

⁸

!

~

,

^j

~ ! , \/

s

7 ^.:r/

/

,

\.

i

6

, ,

^\_i

5 ,

~

4

3 J

,'/

2 •

\

"

^\

^\

ONTOGENY AND EVOLU TION OF KOZLOWSKI E L LA 83

B c

c . .

F

Fig. 9. - Per cent figures of three spe cies of

Kozlows kiella

(P ri b yl) in the faunal composition of six Wydrysz6w horizons ;

A-F

suc cessi ve horizons, a

K. similis

n. sp.,

b K. praetuberculata.

n. sp., c

K. tuberculata

n. sp.

Within the following higher layers the numerical participation of this s pecies increases steadily. In the Grzegorzowice material, however, the f irst rank is occupied by K. praetuberculata n. sp. and K . similis n. sp, (fig. 13) whose numerical participation in the different sampl es varies strongly. .Every max imum share of one species (e. g. K. 3imilis n . sp.) corresponds to the minimum share of another one (K . praeturberculata n. sp.) . K. tuberculat a n. sp. has but few representatives.

K. kozlowskii, described by Pribyl from Givetian beds within the Skaly section, apparently constitutes the terminal stage of the here con- sid er ed evol utionary line. Even at first sight this form strongly differs from its predecessors. The most obvious difference lies in the smaller dimensions of its carapace whose length does not exceed 1.8 mm (fig. 14).

ThE' posterior lobe (L3) is prominent with outline resembling that of L3

in K. similis n. sp. There is , however, a fundamental difference between

t h es e elements in the two species. The posterior lobe in K. kozlowskii

84

G

FRANCISZEK AD AM C Z AK

J

b CJ

K c

Fig. 10. - Per cent figures of three species of

Kozl ow sk i el l a

(Pribyl) in the fau nal composition of five G r zeg or zow ice horizons;

G-K

successive h or izon s,

a

K .

similis

n. sp ., b K .

praetuberculata

n. sp ., c. K.

tuberculata

n . sp,

(Pribyl) has been produced by the gradual evolution of two t uber cless, which finally m er ge into one prominent lobe (L3), while in K. similis n. sp.

the same element has probably been formed in a saltatory mode, becom- ing constant in the fo llowing generations. Thus, t he same detail of cara- pacial ornamentation has, with in the s ame genus, evolved in two diff eren t ways and not contemporaneously, finally resulting in spe cif ic differ entia- tion. This interpretation is also suggested by the ontogeny of the carapa ce (text-pl. I), w hich completely explains the gap within the availabl e m a- teria l derived from Upper Couvinian an d Lower G iv et ian beds .

The cha nges experienced by the here considered species, d ur ing th eir

evolution, were not, nat ur ally , confined t o one char act e r only, s peaking

precisely, in this case to L3 . The velar r idge an d t he for m ation of t he

so -ca lled adm argina l t ubercles on the right va lve of the ost racods are

clo sely correlated with this ornamental d et ail. In specimens of K . prae -

tube r culata n . sp. the subvelar part is narrow and its wi dth in ad ult indi-

vid ua ls does not exceed 0.4 mm: in addition, ·t he so-ca lled admar ginal

r idge (r ig ht valve) has developed along t he f ree m a rg in of the valve. The

ONTOGENY AN D EVOLUTI ON OF KO Z l. OWS K I E L L A 8f)

4 d I

t

3 c _I ^I ~

:2 d _I

r

dJ _I

r

10

mm

5

2 3

4

5

6

7 8

In.stQr~

Fig . 11. - Cross secti on of ventral side of righ t v a lv e (schematic dia- gr a m );

1 K. praetu ber- cu la t a

n . sp ., 2 K.

si- milis

n. sp., 3 K.

tuber- culata

n . sp ., 4 K.

ko- zl owsk i i

(Pribyl ), r ad - m a r gin a l ridge,

t

ad -

margin al tube rcles .

Fi g.

12. -

Wid th of s u bv elar area in v a rious instars ; 1 K.

praet uoerculata

n . sp., 2 K.

ko- zl ows k ii

(Pf lbyl), 3 K.

si m ilis

n. sp ., 4 K.

tu- ber culata

n. sp. Width in mm - on ordinate,

instars - on ab scissa .

1 0 0 %

Fig. 13. - Per cent figures of two species of

Kozlowskiella

(Pribyl) in the faunal composition of five Cou - vinian horizons in Grzegorzowice;

d K. praetuberculata

n . sp., e

K. si- mitis

n. sp . Per cent fi gu r es of numbers of individuals - on o r di- nate, su ccessive horizons - on ab-

scissa.

50

d

e

2 3

4

s

86

1.2 mm

1.1

to

.9

FRANCISZEK ADAMCZAK

.. _{• •} •

• • ,.

• .. .. _{• •}

•

^II

• ,. •

^II

•

• • , ^{, ,}

, , , , ^{, ,}

, , ⁽

" ^,

1 .4 1.5 1.6 1.7 1.8

Fig. 14. - Size of a du lt carapaces of

K. kozl ow skii

(Pribyl). .H e igh t of car apaces in mm - on or di na te, length - on abscissa. Female specimen s marked b y

squares, males - by tr iangles.

subvelar part is considera bl y broader in K. tubercula ta n . sp. , being 0.88 nun (fig. 12). On the other hand , however, instead of the admarginal ridge the appearance is noted in this form of admarginal tubercles which are markedly larger and better pronounced in K. ko zlowskii (Pribyl) (fig. 11, 15). In what the wi d t h of the subvelar area is concerned, it is less than that in K. tub~rculata ^{n. sp., bu t} in proportion to the size of t he cara pac e when w e con sider th a t t h ese a r e forms on e inst ar smaller.

STRUCTURE OF CARAPACE

Ostracod carapaces stu died in t hin sections pr ovid e interesting informa tion regarding the mod e of fo r mation and di fferentiation of the var ious d etails of ornamentation . T his is particularly so in respect to th e marginal parts of th e cara pace and to it s structure since these are s ub ject to minor though occ asion ally f un d amental modifications and h ence ma y be of som e taxonomic s ignifica nce .

In papers on living ostracod s , a v ailabl e to t he writer, problems

conce r n ed with carapacial st r uct u re have been discussed by G. W. Muller

(1894), K. Fassbinder (1912) , R. V. K esling (1951) and others. Many obser-

vations have also been mad e on fossil material: B. Zalanyi (1929),

E. Triebel (1941), 1. H essland (1949), S. A. L evi nson (1949), N. Spjeldnaes

(1951), V. Jaanusson (1957) and R. V. Kesling (1957a).

ONTOGENY AND EVOLUTION OF KOZLOWSKIELLA 87

2

'--~~~~...J!03mm

I ~3mm

5

Fig. 15. - Longitudinal section of right valve of K.

ko- zlowskii

(Pribyl) (schematic diagram);

1

pore canals, 2 dark line , 3 muscle scar, 4 admarginal tubercles, 5 velar ridge,

6 L3, 7 S2, 8 L2.

In the case of species of Kozlowskiella (Pribyl), the author has done a number of thin slides of mature and immature carapaces. Furthermore, he has also studied the thin sections of species belonging to other genera, such as Saccarchites ornatissimus (Giirich)

2,

Polyzygia symmetrica Gii- rich and Polyzygia trigonata Giirich. A "dark line", by Jaanusson (1957) referred to as the bisecting line, has been noted in these forms in some parts of the free margin. In species of Kozlowskiella and in S. ornatissimus it hClJS been ascertained that these lines are regularly arranged over the other parts of the carapace also (fig . 4, 15). Quite recently, Kesling (1957a) describes such elements in genus Hibbardia Kesling where, according to that author's statement, they produce a reticulation readily discernible in tangential s ect io n s, The occurrence of "dark lines" on carapaces is not an uncommon phenomenon. In genus Kozlowskiella (Pribyl) they constitute, a", in Hibbardia Kesling, distinct reticulation also discernible

2

This species has been described by Giirich (1896, p, 383, pl . 14, fig. 3 a, b)

as

Primitia ornatissima

from Lower Couvinian rocks (zone with

Spirifer

dombro-

viensis

Giirich) from Dabrowa near Kielce. In view of the close resemblance of

this species to representatives of genus

Saccarchites

Swartz

&

Whitmore, there

is more reason to refer it to this genus. .

88 FRANCI S Z E K ADAMCZAK

in transmitt ed light und er X 600 magnification of fluoridized valves (fig . 16). Most likely , thes e details thu s fa r recorded in few forms only , ar e a ll of the sam e typ e. This, among other things, s eem s to be pointed out by t he ir position . In polarized light th e st r uct ure of the "da r k lin es "

0.05

mm

L.-~~~""""'"

Fi g. 16. - Fragment of the surface of ca rapace in K .

prae tu be r cu tat a

n. sp . (d ia gram sli ghtl y

simplifie d) ; pc por e ca n a l, dt dark line.

is distingu ishable from t ha t of adjacent pa rts solely by smaller dimensions of calcite crystals. It sho uld be h er e mentioned th at these lines widen out towards the outer su r fa ce of va lves in a fan-like shape an d alw ays occ ur on t he m argin s of reticulation .

In view of thei r m in ute dimens ions t h ese are not pore canals as

allege d by Jaanusson (1957) an d K esling (1957a). In Kozlowskiella (Pribyl)

t heir size does not ex ceed 5 micrones. The occurrence of th e dark belt

may b e interpreted by the existence t he r e, d ur ing lifetime of the ostracod ,

of some organic substance whose presence caused a sli gh tly different

mode of formation of the calcite crystals. Valves when dissolved in

hydrochloric or acetic acid do not rev eal th e presence of any such organic

matter. It seems probable that the dark lines may in some way be

associated with the calcification process of the valves. K. Fassbinder

(1912), who has studied the immature instal'S of the living Cypris pub era ,

states that the calcification process starts earliest within the free margin

ONTOGENY AND EVO L U T IO N OF KOZI.OWSK IELLA

89

area , immed ia tely after moulting. In im mat ure forms of Kozlowskiella (Priby l) t he presence of th e dark line h as been noted already during t he first instar (fig. 17), but within the Iree m argin a rea on ly, no s uch d ar k lines bei ng observable in t he rem ai n in g par ts of the carapace . In t h is insta r t he valves are very fine, w h ile wi t hi n t he free margin area a distinct velar structure is already in ex ist en ce, transected by a dark line. In the following instars the d ark lin es graduall y m ak e t heir appearan ce on t he othe r pa r ts of t he carapace as well . Th eir o r ientation is constant from t h e ventral to th e do rsal m argin . By the '6th inst ar th e w hole carapacial surface is covered with them. The same de tails of struct ure have been noted in Sacca rchites orn at issim u s (Gurich), bu t they

Fig. 17. - Cross sections of three earliest instars of K.

praetuberculata

n. sp . (di agram f igure).

ar e m issin g during the earliest instars of this species; the ve la r str ucture being, moreov er , in t hese for ms less prono un ced, and t he retic ulation more deli cate. Here the dark lines begin to appear du r ing t he 3rd or 4th instar, in t he sa me m an n er as in genus Ko zlowskie lla (Prib yl) .

Pore cana ls show a most regula r a r ran gemen t with in retic ulation pi ts (fig . 4, 15, 16). They are funnel s hape d canalets readily discernibl e on fl uo r idized valves (fig. 5). Th ey are absent fro m t he fre e m argin area.

ONTOGENY

Th e p ro bl em of ontogeny, i. e . of developmental cha ng es experienced

by the carapace in the course of success ive moultings , is one of great

signif icance for phylogenetic studies. Stress has been laid on it in many

pa per s beginning with that by M. Verworn (1887) . So far , however , it

was not possible to draw any general phylogenetic conclusions concerning

the described forms on account of the inadequacy of the available ma-

te ri al. Often the described instars were not linked subsequently with

90 FHANCISZEK ADAMCZAK

phylogeny or were investigated from a different aspect. This will be easily understood upon considering that immature forms are not al w ay s found in the residuum of the washed material.

50 4

3

5

~o

10

6

350 500 1000 1500 2000

~

F ig. 18. - D ia gr a m figure showing dimensions an d numbers of carapaces dur in g va ri ou s instars in K.

praetuberculata

n. sp, Numbers of carapaces - on ordinate,

size in micrones - on ab scissa.

On evidence of the available material the writer has been able to identify probably all the instars in the here considered three new species of genus Kozlowskiella (Pribyl) and in the form previously d escribed by Pribyl (1953) as Ulrichia (Kozlowski ella) ko zlowski i . Since these are closely allied species it was possible to clarify their interrelations. In con ne cti on with these observations the writer is of the opinion that the sp eciation may take pl ace eith er by sudden l eaps (K. similis n . sp .) or by wa y of slow evolutionary changes a s is illustrated by the carapacial ontogeny of K. praetub er cu lata n. sp., K . tu ber cul at a n . sp. and K . ko- z lowskii (Pribyl) (t ext-pl. I) .

The numb er of moults within Beyrichiacea has not been exactly determined , ranging from 6 to 10. Apparently this is controlled by the sam e factors as those now acting i n the living forms (Kesling, 1952a).

In species of genus Kozlowskiella (Pribyl) 9 instars, i. e. 8 moultings, have been ascertained.

Carapaces of immature forms are as a rule complete, but the yo un gest in stars are very scarcely represented. They are fragile and brittle, often filled in by calcite. S epar at e valves of instars 5, 6 and 7 a re fairly common.

Consid erable difficulties have been en countered in distinguish in g the

AC TA PALAEO NT OLO G I C A POLO "reA, VOL. III F. ADAMCZAK, TEXT-PL. I

~

~

~ )

e:J

C9

i ~

l!)

((!J

G

f aces in:

A

K

praetubercul ata

n. sp ., B K.

. . . di .d I ontogeny

0

ca ra p

c • • '. •

S li gh tl y sc hema tic diagra m

_tu be r c u l a t a

of

In

n

IVI

. sp ua ., C K .

kozl owski i

(Prib yl), D

K.

slm zlls n . sp.

ONTOGENY AND EVOLU TION OF KOZLOWSKIELLA 91

'i mmat u re instars in the t h r ee Couvinian s pe cies. At first sight, their ea r liest instars are practically indistiguishable. The va r io us lin es of ontogeny could be differentiated by indirect means only, e. g. a close comparative study of t he diff erent in st a rs, with respect to their state of preservation, has revealed that in representativ es of K. tuberculata n. sp. t he colouration of the carapac e is n early always darker that t h a t i n the r emaining s pecies. Such biometric methods as determining th e

·d imensions in the va ri ou s instars , th e growth coefficient etc: did not

prove of any h elp in th e st udy of t his problem. The yo un ges t instars differ very insig nifica n tl y in what size is concerned . In order to ident ify the v arious instars K esling's (1953c) m ethods w ere ap plied, theoretically based on Brooks law . When dealing with large amounts of material t hi s method has proved extremely valuab le. Furthermore, a graph ha s been plotted of immature and adult in divid u als (fig. 18), which coincides - en t ir ely with data obtained with the help of a "sli d e rule" .

On evidence of such morphological el ements as S2 , L2 and L3 , also on reticulation , it was possible to d et ermin e the generic position of ca- rapaces already in the first ins tar. Specific characters make the ir ap- pearance later and stabilize in insta,rs 6 an d 7. This, however, is not alwa ys t he case. In Ko zlowskiella t u berculata n . sp ., for instance, the specific position could be assigned already in the 4th instar. Sexual dimorphism - do es not occur before the last moulti ng. In some instances, however, on the size of carapaces (K. praetuberculata n. sp.) we are led to the sug- gestion that sexual maturity is reached e arlier (in the 8th instar).

When study in g in div id ual on toge ny the w r iter h as t aken into con- s id er a t io n the two essen tial trends, mentioned at the beginning of the p aper , of which t he fi rst is represe n ted by K. praetuberculata n . sp. , K. tuberculata n . sp. an d K. k ozl ow slcii (Pribyl); th e other one - by K. simili s n . sp.

In K . praetu ber cul ata n. sp., as in the other species, S2 appears as ea rly as the first instar . L2 and L 3, toget her with re t icula tion , a re still i nd istin ct. In t he 3r d in st ar, a d el ic at e border is o utlined , fo r med by th e ar rangement into two pa rallel ro ws of the r et icu la tion m eshes. In t he 4t h instar S I is o u tli ned, while in instar 6 or 7 two m inut e t uber- cles appear on the posterio r lobe with a co ns ta nt tendency to increase (text -p l. I A) .

K. t u berculata n . sp . displays already in th e fi rst instar we ll dev e-

loped L2 and L3, as w ell as S2. Th e r eticulati on here is at th a t stage

more conspicuous that in t h e previous s pec ies. After the s econd moulting

the tubercles on L3 are nearly completely formed (text-pl. I B). SI be-

c om es outlined in ' the following instar.

92

^{FRANCISZE K ADAMCZA K}

The las t species of t his evolu ti ona r y line is th e Giv eti an K. ko zlo w - skii (P rib yl). Its fi rst instal' is smaller t han in the previously mentioned spe cies , while t he other ch ar a ct er s coincide. Alre ady in the second inst al', however , two min u te t u bercles m ak e their appea rance on L3 . SI appe ars, as usually , in the 4th instal'. Up to the tim e of the 6th or even t he 7th mou lting two tub ercles persist on L3. Aft er t he 7th moulting , i. e . in the 8th instal' , L3 becomes mo r e promin ent and produces a large k nob not car rying any tubercles on its surface (text-pl. I C).

S2 is that character of ornamentation w hich has fundamen tally altered the sculpt ure of the carapace of Kozlowskiella (Pribyl). It s for- mation is reasonably probabl e during t he youngest instal's only, when t he resistance power of the carapace agains t cent r ipetal traction is r elati- vely weakest (add uctor muscl e). All additional alterat ions oc cur arou nd t he sulc us wh ich h as th us formed, i. e. the formations of lobes L2 and L 3, t he en lar ge ment of the subvelar area as w ell as several m inor chan ges bro ugh t abo u t by th e fo rmat ion of these elements.

The appeara nce of a ne w character was invest igated in the diff eren t instal's (text-pl. I) by ob ser ving the mo ment and mode of its fo r mati on an d its changes in subsequent instal's. In K. praetuberculaui n. sp ., for instance, t ubercles on L3 m ak e their appearance in later stages of onto- geny; subsequently t his character transgresses onto earlier stages (K. t u- berculaui n. sp .) whic h is proba bly connected w ith stabilization of t h is character. These elem en t s, however, a r e not constant in the here co n- sid er ed evolutionary line. In K. kozlowskii (Pribyl) the t ubercles occur in yo ung instal's only and constitute transitional elements leading to t he st rongly developed L3 . Furthermore, on ontogeny of the carapace in K. praetuberculata n . sp. it may be inferred that this species is, in a ll probability, the ancestral form from which th e other r epresentatives of genus Kozlowskiella hav e derived .

SYSTEMATIC DESCRIPTION

Suborder P alaeocopa H enningsmoen , 1953 Superfamily Beyrich iacea Ulrich & Bassl er , 1923

F amily Beyrich iidae(?) J on es , 1894 G enus K ozlowskie lla (Pribyl, 1953)

Ge no type: Ulrich ia (Kozlowskiella) kozlowskii P ribyl (1953 , p. 241- 244, pl . 1, fig . 1-18) .

Diagn osis . - Trilobat e fo rms, hinge line st raig ht . In central part

of carapac e an add uctor muscle sca r . Velar rid ge along the free ed ge .

ONTOGEN Y AND EVOLUTION OF KO Z L O WS K I E L L A 93

S urf ace of carapace reticulated. Well pronounced dimorphism.

Representatives : Ko zlowskieHa ko zlowskii (Pribyl, 1953) Kozlowskiella pra'etuberculata n. sp.

K ozlowskiella tu berc u lat a n . sp.

Ko zlo wskiella similis n . sp.

Remarks. - Genus Ko zlowskiella (Pribyl). recorded from Middl e Devonian rocks of Wydrysz6w, Grzegorzowice and Skaly (Lysogora r egion of th e Holy Cross Mts.) , by Pribyl (1953) described as a new sub- genus within genus Ulrichia Jones , is by the present writer separ at ed into a new genus, independent of Ulriclua, and tentatively included into the family Beyrichiidae. This conclusion is founded on detailed st ud ies on the morphology, on tog eny and var ia t ions of the considered forms , grounded chiefly on the dimorphism sim il ar to the cruminal type , as defined by Jaanusson (1957) .

Kozlowskiella (Pribyl) displays similari t ies with genus Ulrichia , whose representatives ar e mentioned by Pribyl, in some morphological details only. The cardinal difference between Ulrichia and Ko zlowskiella lies in the presen ce in th e latter genus o f Sl and S2 , and in th e distinct sex ual dimorphism occ ur r ing throughout a ll th e sp ecies of this genus . An additi onal difference is a w ell de veloped muscle area in th e central po r t io n of th e va lve . Of the other forms with which K ozlowskiella is compared by P ribyl , that of Bolbiprimitia Ulrich only di splays a certain resemblance; also some other forms subseq uent ly described and referred to here below. Th e assignmen t o f K ozl owskiella to genus Ulrichi a has also been questioned by J aanusson (1957) . He write s that in type of lob ation this gen us resemble s Thomasatia Kay and pro bably for this reason h e places K ozl owskiella (Pribyl) w ith in the family Bassl eratiidae.

T he r ef eren ce of gen us K ozlo w sk iella to the B eyrichiidae is no t beyond doubt in the light of t he lat est stud ies done by K esling (1957a) an d of cer ta in o bservations ca r r ie d out by t he present w ri t er on his ow n mater ia l. A comparison of o ur form wit h ge n us Hibbardia K esling (1953b ) r ev ea ls ce rta in a nalogies . These consist amo ng others of t he ex ternal resem blance of di morphis m and clo se sim ilar ities in the develo pment of the vela r r idge and of or namen tation. The cardin al diff ere nce is t hat of the o rig in of dimorph ism in K ozl ow sk iella.

Th e origin of gen us Kozlowskiella is not thoro ug hly, kno wn . On the comparison of ce rtain m orphologic al ele ments it may be supposed to h a ve derived f rom forms coming ne ar t o Saccarc h it es or n at issim us (G ii- r ich ), di stinguished by dimo r phism resembling that in K ozlo wskiella.

Sa ccarchit es ornatissimus di splays a moderate amount of r es emblance

to th e species desc ribed by Swartz an d Whitmore ,(1956) as Sacc arc hites

94 FRANCISZEK ADAMCZAK

saccu iaris. Those authors allege that the considered form resembles genu s PhLyc ti scapha described by Kesling (1953a) . Nevertheless, though these forms do display a certain resemblance, yet the present writer is of the opinion that the w e'll known genus Saccarchites has more charact ers in common with S. ornatissimus (Glirich) than with the representa tives of PhLyctiscapha. Features r esembling those in Phlyctiscapha are t he t ype of dimorphism , outline o f carapace and the muscle scar.

Noteworthy a re al so forms which in some re spects a re similar to Saccarchites , in others to K ozlowskieHa. They ha ve been described by Polenova (1955) from the Volga-Ural province in the Soviet Union ter r i- tory und er th e name of AparchiteHina decorata. One of these forms in particular , namely AparchiteHina cf. decorata , kindly present ed to the ' writer by Mrs . Pol enova , is to some extent a transitionary form. Parti- cularly noteworthy in this spe cies is the muscle scar, developed similarly as in Saccarchit es , whil e the carapacial outline an d detail s of ornamen- tation com e closer to these characters in Ko zlowskieUa.

It seems reasonably probable th at forms such as : Saccarchites sac- cularis Swartz & Whitmore, 1956, S. ornatissimus (Glirich, 1896) and AparchiteHina cf. decorata Polenova, 1955 - constitute a morphological evolutionary line, with S . saccu laris as the probable ancestral form , in view of its poorly differentiated ornamentation an d its occurrence within Upper Silurian rocks. Th e two other species have been recorded from t h e Middle Devonian.

R. Ruedemann in 1909 (fide Ellis & Messina , 1952-57) has described MacronoteHa jragaria from the Ordovician of the United States of Ame- ric a. This form is an interesting on e on account of its res emblance to Sa ccar chi tes ornat issimus (Glirich) , as is stated by its au thor. In both t hese forms ther e are s imilarities of the outline of carapace, of ornamen- tation and of muscle sca r . A comparative study of S. ornatissimus with MacronoteHa hyper cala Kesling & Kilgore (1952) points out some inter- esting conclusion s too. Dr. Keslin g was kind enough to provide the present writer with an assemblage of Devonian ostracods from North America. Direct comparisons of the two above mentioned s pec ies did not , however, lead him to detect any differences between the immature form of S. ornatissimus (5th and 6th

instars~

and the American species.

Presumably, a detailed st udy of these forms may clarify this prob-

lem . Sections would , it is believed, be of special significance. Forms of

S. ornatissimus, including their ontogeny, have been studied by the

writer. He has .also made a number of thin sections of both, the immature

and adult, forms and has arrived at the conclusion that they may be-

phylogenetically related with Ko zlowskieUa (Pribyl).

ONTOGENY AND EVOLUTION OF KOZLOWSKIELL A

Ko zlowskiella praetuberculata n. sp .

(fi g. 19, 20; p l. I, I II)

95

Holotypus:

fe ma le cara pace in pi. I, fig. 1

a-e.

Stra t u m typieum:

Lower Couvinia n, Lys ogor y region, Holy Cross Mts . Locus

typi eu s:

Wydrysz6w.

Derivatio nominis: praetu bercu lata -

specie s less advanced than

K. tub er- eulata.

Diagn osis. - Trilob ate, outline of carapace suboval, hinge line st r aigh t ; subv ela r area narrow; two sma ll tubercles on L3. L eft valve overlaps the right along the free edg e. Surface reticulated . D elica t e ad- marginal ridge on subvelar area (ri gh t valve). Distinct di morphism.

Descript ion . - Outline of carapace subova l, preplete; dorsal border st ra ight . A velar ridge along the free edge. Dorsall y , S l and 82 extend fr om a common base. One of them, 81, follows the antero-ventra l d irec- tion ; the other, 82, markedly. longer, is perpe ndic ular to the do r sa l

Table

1

Kozlowskiella praetuberculata

n. sp.

Dimenslons" of carapaces and growth factor in the several instars

...

'"

0 '" ^{... ,}

.c: .c: .c: Q) .c: 0- Ol .c:

.c:

_~-.S

:s::_ ^I::

^~Q)

Instar

^{-I-< -I-< -I-< -I-<}

.c;;_

"'1-<

bli- I:: I: 0-

~o ^~Ol~_

I::fll-<I:

~

0 - 0

.~

I:

~o

0-

^.!l:.~^~

I:

~_o~

0 iiS ... 1: 0-

~o

Q)I:

^I-<U

Q)00l1:

^I-<U

Q) I:

^{". u}

.c:1: t5~

^{.- 't:l}

^{Ol I:}

^{I-< U}

...:l~ ~~ ...:l't:lE_ ~~ :r:~ ~~ E-<~ S::0l1::~ ~~

1 0.36 0.28

1.29 1

0.28 ,·,, 1 ^{0.20 I I 0.08}

1.22

^I

1.30 1.50

II 0.44 0.36 I 0.32 0.26 I ^0.12

1.18 1.05 \ 1.25 1.15 , ^1.16

III 0.52 0.38 0.40 0.30

^I

0.14

1. 26

1

1.20

I

1.33

^I

1.23

I

1.28

IV 0.64 0.48 0.48 i ^{0.40 0.18}

1.18 1.25

I

1.25 ,

1.20 1.44

V 0.76 0.60 0.60 I ^0.48 : 0.26

1.31 1.26 1.20 1.08 1.07

VI 1.00 0.7 6 0.72 0.52 0.28

1.32 1.26 1.33 1.38 1.21

VII 1.32 0.96 0.96 0.72 0.34

1.27 1.33 1.25 1.24 1.17

VIII 1.68 1.28 1.20 0.88 0.40

1.14 1.15 1.10 1.36 1.00

\> 1.92 1.48 1.32 1.2 0 0.40

(J

1.84 1.40 1.28 0.88 0.40

• Quot ed data are modal values,

FRANCISZEK ADAMCZAK

border. In th e centre of carapace S2 becomes club-shaped and bears the muscle scar. Lobes mod erately prominent. Posterior lobe (L3) tending t o produce tubercles . On th e right valve a well developed hinge groove , over the entire surface, with t h e exception of the triangular area in the s ubvela r area , the larger on t he left valve, the smaller and more delicat e o ne - the so-called admarginad ridge - on the right valve.

Dimensions and gro w t h fa ctor of ca rapaces - see tab le 1.

1.5 •

'- • •

mm

...

1.4 • • • ^• •

• ,

^'lll

•

• ., ^, _~

1.3 • • , • _'"

1.2 , , ^{, ,} _•

, , ,

1.8 1.9 20 2.1 2.2

F ig. 19. - Size of carapaces in ad u lt forms of K.

prae- tuberculata

n . sp . H eigh t of ca rapaces in min - on or d in a te, length - on abscissa. F em ale specimens

ma rked by sq u a r es , males - by triangles.

Va riation . - Size of va lves varies r ath er st ro ng ly in d ependence on t he stratig raphic ho r izon f ro m which the mat erial was sa m pl ed. Th e reti culation m eshes are usu ally subpe ntagonal and uniformly dispersed over t he en ti re surfa ce , wi th th e exce pt ion of th e triangular area in the a ntero -do rsal po rtion of t he ca rapace . W ell d eveloped pore canals in t h e ret iculation .

Dimor ph ism . - In fema le specimens , which pr edom inate amo ng

m a tu r e ind iv id ua ls (68 pe r cent), t he ventral valve is distinctly swo lle n

(fig. 19).

ONTOGENY AND EV O L UTION OF KOZLOW SKIEL LA

97

Ontogeny. - Th e collected immature valves probably r ep r es en t com- p let e series of instars, It is not excluded that in some cases adult indivi- duals also moult their carapace, t his being s ugges t ed by the great si ze

range of mature va lv es (fi g. 20).

In star I - Dimensions (in mm): length 0.36, h eigh t 0.28, th ickness 0. 20. Outline of valve d ist inctly preplet e , hinge line s traight. L2 a nd L3, and median 8 2 al ready w ell m arked. Delicat e velar ri d ge ex tend in g along the fr ee edge; reticulation st ill rathe~ i ndist inct.

0

-

-

r--- t - -

I - -

-

I - -

I - -

l

5 20

o/c

10

1 5

2 3 4 5 6 7 8 9

insrcr s

Fig. 20. - Per cen t figure of ca r a paces of K.

praetuberClllata

n . sp. in vario us ins ta rs .

In star II - Dimen sions (in rnm): length 0.44 , height 0.32, thickn ess 0.26. Va lve s till bilobate; reticulation more distinct; L 3 larger. The r e- m aining characters unchanged.

In st ar III - Dimen sions (in mm) : length 0.52, height 0.40 , thickness 0.30 . Reticulation mesh es larger than in earlier instars; L2 and L3 more pro m ine n t.

Instar IV - Dimen sions (in mm) : l ength 0.64, height 0.48 , thickness 0.40. In this instar 81 is outlined , gently arcuate, som ewhat obliquely direc te d forward. T he edg e on L 3 faintly outlined .

In star V - Dimension s (in mm): length 0.76, heigh t 0.60, thickness 0.48. 8 1 a nd 82 deepened. Ed g e on L3 di st inctly m arked. R ema inin g cha r act ers u nch ang ed .

Inst ar V I - Dimensions (in rnm) : len gth 1.00, height 0.72, thickness 0. 52. Various ornamentation details are in t his s ta ge quit e distinct. Two minut e tu be rcles appear on L 3. A small rib is outlined between 8 2 and 83.

Instar VII - Dimensions (in mm): length 1.32, height 0.96, thickness , 0.72. Tubercles on L3 more distinct ; th e remaining characters unchanged.

Acta Pataeontotog tca Pol ontca - vol. IIIj2 ₇

98

FRANClSZEK ADAMCZAK

Instar VIII - Dimensions (in mm): length 1.68, height 1.20, thick- ness 0.88. This instar precedes the mature form. Small tubercles on L3 st ill increase. Other details of ornamentation are those of mature forms . '

Insta l' Le n gth of H ei ght of c a r a pace

(mm )

carapace

(mm)

I 0.3 1 - 0.36 0.20 - 0.28

II 0.37 - 0.45 0.22 - 0.32

III

0.47 - 0.56 0.32 - 0.42

IV 0.59 - 0.68 0.42 - 0.55

V 0.69 - 0.88 0.50 - 0.6 3

VI 0.94 - 1.14 0.62 - 0.96

VII 1.17 -1.43 0.96 - 1.15

VIII 1.48 - 1.82 1.10 - 1.35

Ad ult 1.84 - 2.40 1.32 - 1.50

R em ark s. - Kozlows k iella pra etub erculata n. sp. displa y s numerou s analog ies wit h the oth er species h ere described. Differ ences between them consist in d et ails of orna men t atio n and varying size. There are also some dif ferenc es in the successive onto genetic st ages . This species is sim il ar to A parc hi te llina cf. decorata Polenova . Its r esem blan ce to genus Hib- bardia K esling is by t he writer r egarded as l ess st r ik ing, chiefly du e to different t ype of dimorphism .

K ozlo w skiella tu be rcu lat a n. sp .

(fig. 21, 22; pI. II, IV )

Holotypus:

female carapace in pl . II , fig. 3

a-c.

Stratum typicum:

L ow e r Co uvinian, Lysogory region, H o ly Cross Mts .

Locus typicus:

Wyd rysz6w.

Deri v a ti o nominis: tuberculata -

two distinct tubercles on L 3.

Diagnosis. - Trilob at e , outline of va lve pre plete; hinge lin e straight.

Two di st inct t ubercles on L3. A ve lar r id ge alo ng the f r ee edge of ca- rapace. Subvela r area broad . Surface ret icula ted. Well defin ed dimor- phis m.

Description . - V al v es of th is species are of gr eate r size than in any of t he r em ain in g fo rms of Kozlowskie lla (P rib yl). The posterior lob e (L3) bears two distinct t ube r cles cons tituting one of the specific ch aract ers.

51 and S2 exten d fr om a com mo n base in the dorsal part o f th e valv e,

separ a t ing L1, L2 and L 3. S1 g ently arche d forward , while S2 occupies

a centr al position. Mu scl e scar in the middl e of valv e. Subvelar area

ONTOGENY AND EVOLUTION OF KOZLOWSKJELLA

99

broad (0.88 mm) , delicat e admarginal tubercles on the right valve. Dor- sally (right valve) w ell developed h.ix:ge groo ve, expanded at both ends . Pore canals in reticulation meshe s.

L.~~t

"v alv e overlapping the right.

.

'''.\

. '

Dimen sions a nd grow t h f actor of carapaces .,-:- s ee table 2.

\'. ..._~-., _.~.!.: ..' .

Tab l ~

2

· . f , ... • . . .

•'J"ot , . .

"

~

Kozlow ski ella tuberculata d. s p, ,',

Dim ensions* ' or" ca r apaces and g row th fa'~tQr' 'i~ th e seve ral in stars

.'

J

...

, r

Ul

I

^{0 Ul}

" _{'6n ~}

.c .c s:: ' ' .c .. _{.... .c} Q) _{.c .c}

In s tar I ^.c _{00 -}

^{~ ~ ' ~_}tlO"'tlO^.--

_~~,-.

^.~

^...

^{~ .!o:_}

^{c ....}

^{~ .c~~}

^....

^~

.~~. ~B

^{~ 0 ... eu~- ~ 0}

s::

~

o B .' s::

~ ~ ~

. 8

t;.. .~ ~ ^{0 ....} '0

E_

~ ^{0 ....}

I ~ £.

0^~tJ~

...:l'OE

^Q)o"'

_

^~ _{, 0~ :r:}^Q)~_~ ^I _d~^{~'-' .c~}E-<_ ^{~ tJ}

~ ~~£.

^{~ tJ}

I ^{d~ d~}

I

I ^I I

^f

^{! . 0.26 j I 0.22} I I

I 0.40 0.32 I 0.08

I 1.20 1.13 1.23 1.09 I ^1.00

II

^I

0.48

I

0.36 I 0.32 0. 24 I 0.08

I _{1.16 1.27 I 1.18}

^I

_1.33

I ^1.50

I

^I

III 0.56 0.46

1.2 1 j ^{0.38 . 0.32 ! 0.12}

1.28 I ^I _1.26

^I

_1.12

I

2.00

IV 0.72 0.56 0.48

I

0.36 I

^I

0.24

1.22 i ^{I 1.28 I I 1.33}

^I

^1.33 I

^"

^1.25

V 0.88 0.72

I

0.64 0.48 I 0.30

1.36

1

1.27 I

1.31 1.33

I ^1.20

VI 1.20 0.92

^I

0.84 0.64 0.36

I

I

I

1.33 I ^1.39

I ^{1.28 1.37 1.50}

I

VII 1.60 1.28 1.08 0.88 0.54

I

1.15 I 1.15 I 1.18 I _{1.13 1.11}

VIII 1.84 I

1.26 [

1.48 I ^{I 1.28 1.00} I

I ^0.60

I

I ^1.21

^I

^1.25 i 1.48

^I

1.46

9

I ^2.32

^I

^1.80

^I

^{, 1.60}

^I

^{1.48 ! 0.88}

0 1.96

^{I I}

1.52

^I

1.44 1.02 0.68

I I

I ^I

^{I ,}

!

Quoted dat u n re mudal va hie....

V ar iation . - Only the si ze of va lves is sub ject to certa in va ri ati ons.

The su bvelar len gth/ width r atio va r ies f ro m 4.4 to 7.1 (fig. 21).

Di m or phi sm . - In f emal e s pecimens the va lves are ven t r ally strongly swoll en. T he m al e specimens are mo re sle nder; th ei r valves consti tute a minority a mong ad ult sp ecimens.

On t ogen y (fig. 22):

I n star I - Dimensions (in mm): length 0.40 , h eight 0 .26, thickness 0.22. Ou tline subova l; r eticulation d ist inct. L 3 forms a fai rly poi n ted tubercle. Valve monosulcat e.

Instar II - Dim en sions (in mm) : length . 0.48, height 0.32, thickness'

0.24. Outli ne a nd detail s of m orphology without changes.

100

FRANcmZEK ADAMCZAK

2

Fig. 21. - Diagram of ca r a p a ce length/width of subvelar area ratio: 1 K .

praetuberculata

n. sp .,

2 K

similis

n . sp.. 3 K.

tuberculata

n. sp .

In st ar III - Dim en sion s (in mm): length 0.56, h eight 0.38, t hi ckness 0.32. T wo t ubercles make th eir appearance on L3 .

. Instar IV - Dim ensions (in mm): length 0.72, h eigh t 0.48, thickness 0.38. In this instar 81 is initially o utlined. The wi dth of the s ubvelar area hasdoubled.

Fig. 22. - Per cent figure of carapa ces of K.

tuberculata

n. sp . in vario u s in stars. Per cent fi- gure of the number of in divi- dua ls - on or di nate, instars

on abscissa .

0 , . - -

, . -

f - -

---=

^-

- , . -

-

5 15

10

20

'Yo

2 3 4 5 6 7 8 9

ln~tor,s

Instar V - Dimen si ons (in mm) : length 0.88, he ight 0.64, thickness

0.48. Details of ornamentation more distinctly marked and not subject

to any essential changes during the following instars.

ONTOGEN Y AND EVOLUTION OF KOZLOWSKIELLA

.101

Instar VI - Dimension s (in mm): length 1.20, height 0.84 , thickn ess 0.64. No cha nges.

Inst ar V II - Dim en sions (in mm) : length 1.60, height 1.08 , thickness 0.88. In t his instar t he subvelar area increases considerably. Details of orna me ntati on h~ve been definitely developed.

Inst ar VIII - Dimens ions (in mm): le ngth 1.84 , height 1.28 , thick- ness 1.00. This ins tar precedes the m atu r e form .

Instar I

Length of He ig h t of ca rapace

(mm)

carapace

(mm)

I I ^{0.29 - 0040 0.22 - 0.26}

II ^I_I

0040 - 0048 0.27 - 0.3 2 III -I ^{0048- 0.56} 0.32 - 0.38

IV 0.56 - 0.72 0.37 - 0.55

V 0.75 - 0.89 0.50 - 0.68

VI 1.00 - 1.28 0.64 - 0.84

VII 1.38 - 1.60 0.87 - 1.10

VIII 1.64 - 1.85 1.10 - 1.30

Adult

1.88 - 2.70 1.42 - 1.80

Remarks. - K ozlo w sk iell a tu bercu lat a n . sp. is a transitionary stage in the evolu t iona ry t rend l eading f rom K. praetuberculata to K. ko- zlow sk ii (Pribyl) . A n um be r of m orphological characters trac ed t hro ugh- out its on togeny con firm this ass um ption. Tubercles sit uated on L3 are of particular significa n ce wh en comparing these forms. In K . tuberculata n. sp. they make their appearance during t h e earliest stages of ontogeny (3rd instar) , while in K. k oz lowskii - f ro m 2nd instar; in K. praetub er- cu lata n. sp., wh ich is und oubtedly a mor e primitive form, they appear lat er and are less strong ly d ev elo p ed. F ur t h er mor e, in K . tuberculata n. sp. admargi nal tub ercl es on t he ri ght valve are eq uivalent to th e adm ar ginal ridg e in K. praetubercu lata n . sp. (fig. 11).

K ozlow skiell a k oz low skii (Pribyl)

(fig.

23, 24;

pl. II)

Type spe cies: Ulri chi a (Ko zl ow ski ell a) ko zlowskii Pribyl (1953, p. 242-244 , pI. I, fig . 1 -18).

Diagnosis. - Th e ori ginal diagnosis , as given .by P rib y l (1953, p. 318),

is: "Anterior node placed much lower than the post erior node , which

us ua lly projects above the dors al margin . There is a de ep fu r row b etw een

two nod es. A nterior to th e anterior node there is a lso a furrow directed

obliq ue ly forward. The su rface of the va lves and nodes is coa rsely re ti -

c ula ted" .

102

FRANCISZEK ADAMCZAK

Description . Carapac e trilobate , almost preplete; hing e line st ra ig ht. Hinge groove o n right v alve along the dorsal border. Posterior lobe (L3) in th e shape o f a prominent knob. Velar r idge alo ng th e free edge. S1 ex te nds somew ha t obliq ue ly in r elation to S2 , sepa r at ing th e two lob es . Th e cen tral part of t he va lve is occupied b y the m edi al fur- row (S2), wh ich st re t ches to the centr e of th e va lve; it is t here swo llen, s uggesti ng the mu scl e sca r. V er y fi ne reticula t ion discernible on th e poste r ior lob e (L3). Admarginal t uber cles d ev eloped on the right va lve along t he f r ee edge. Hinge f urro w as in t he rem aining species, with a hinge list on the left va lve.

Dim ension an d growt h factor of ca rapaces - see table 3.

Tabl e 3

Kozl owski ella kozlowsk ii

(Pri by l)

Dim ensions > of ca r ap a ces an d g rowth fac t or in the seve ral instars

I I

.... I

I '"

0

'" ts"6D _~

"c

.c

=: co .:: ^.c I

^"c

^al

^{"c "c}

Instar .... - ^... _~8 .!::- ~8

^l::

...

"c ...

...

elI- ~ 0

~ ~ ~1

I

.!<:- ~ ^{0 ~etSetS-} ~ 0 l::

f:

^{0 .... 0 ...} .~

f:

^{0 ....}

.::! 1:

^{0 ....} _~

E- f:

^{0 ....}

al f:

^{... U 4Jo ctl}

f:

^{... u}

al f:

^{... u}

-cf:

^{... u}

;::'C

^ctl

f:

^{... o}

....l _

_(j~

....l'CE _

(j~

::r:_

(j~ 8 _ (j~ ctll::_ (j~

I 0.28 0.26 I I ^0.22 I 0.18 0.0 8

1.28 1.23 I 1.18 1.11 1.25

II

0.36 0.32 0. 26

₁

0.20 0.10

1.33 1.00 1.15 1.40 1.20

'ill 0.48 0.3 2 0.30 I 0.28 0.12

1.20 1.50

^I

1.40 1.00 1.00

IV 0.58 0.48 0.42 0.28 0.12

1.24 1.33 I 1.28 1.28 1.66

I

V 0.72 0.64 0.54 ' 0.3 8 0.20

1.26

I

1.25

_I

1.25 1.26 1.60

VI 0.91

I

0.80 0.68 0.48 0.32

1.14 1.15 1.17 1.08 1.00

VII 1.04 0.92 0.80

1.10 I ^{0.52 0.32}

1.30 1.17

0.88 1

1.15 1.25

VIII 1.36 1.08

I

0.60 0.40

1.23

,

1.25 1.3 1 1.56 1.40

Q

1.72 I ^{1.36 1.16}

I

0.94 0.50

I ,

0'

1.6 4

I ^{1.24 i 1.16 ,}

^I

^{0.60 0.5 6}

* Quoted da rn tire modal va lues.

Var iation. - Length of v alv e ranges f rom 1.4 to 1.8 rom and the length/width ratio from 1.3 to 1.7 (fig. 23).

Dimorphism. - In female spec im ens the a nt ero- v entral portions

of the carapace are distinctly swollen. As compared against the remain-

ing species of genus Ko zlowskiella (Pribyl) , this ventral inflation has

been shifted somewhat anteriorly . Furthermore, it has been ascertained

ONTOGENY AN D EVOL U TIO N OF KOZ L O W SK I FJLL A

103

25 %

- I - -

15

5 r---

mm

23

15

13 14 1.5 16 1.7 L/H 2

3

⁴

F ig. 23. -

K.

k oz lowskii (Pfibyl ), variation diagram . P er cent

fi-

gure in the com p ositi on of va- rious groups - on ordinate.

Fig. 24. - Dia gr a m figure showing cara - paces di mensio ns of f ou r species of genus Kozlow sk ielta (Pribyl) in Mi ddle Dev o- nian layers of H oly Cross Mts. Supposed changes w it hin the Uppe r Couvinian and Lower Giv eti a n indicated by broken line : 1 Lower Couvinian, 2 Uppe r Co uvinian,

3 Lower Givetian , 4 Upp er Givetian.

o n the available m at er ia l that fema les cons tit u te 54.7 per cent of all matur e forms . He nc e, among Gi vet ian fo rms, t he n umb er of m ale spe- cimens has increased (fig . 14).

Instal' Length of Height of

carapace

(mm)

carapace

(mm)

I 0.28 - 0.30 0.21 - 0.26

II

0.32 - 0.36 0.22 - 0.27

III

0.38 - 0.48 0.20 -0.30

IV 0.49 - 0.5e 0.30 - 0.42 V 0.61 - 0.78 0.38 - 0.54 VI 0.79 - 0.91 0.50 - 0.70 VII 0.93 - 1.12 0.62 -- 0.80 VIII 1.18 - 1.38 0.78 - 1.00 Adult 1.40 - 1.88 0.92 - 1.24

Ontogeny:

In st ar I - Dimensions (in mm): length 0 .28, height 0.22, thickness 0.18.

Bilobate form ; outl ine of ca rapace preplete. L3 fairly prominent and sharp pointed. Delica t e r eticulation on surface of va lves. Velar ri dge along the free margin.

Instar II - Dimens ion s (in m m) : length 0.36, height 0.26, thickness 0.20. Two min ute t uber cles appear on t h e anterior lob e (L3). Remaining fe at u res witho ut changes .

In star III - Dimensions (in mm) : le ngt h 0.48, hei ght 0.30, thickn ess

0.28. L3 and t he t u ber cles more prominent .