A new species of Glgphea (Decapoda: Palinura) from the La Meseta Formation (Eocene) of Seymour Island, Antarctica

RoDNEY M. FELDMANN andANDRZBI cxŹoZICK[

Feldmann, R'M. & Gaździcki,A.1997. Anew speciesof Glyphea (Decapoda:Palinura) from the La Meseta Formation (Eocene) of Seymour Island, Antarctica. - Acta Palaeon- tologica Polonica 42, 3, 437 445.

A new species of palinuran lobster, Glyphea reticulata, from the lowermost part of the Eocene La Meseta Formation on Seymour Island, Antarctica, represents one of the stratigraphically youngest species of Glyphea. The occurrence of the last vestiges of what was previously a cosmopolitan genus in a region dominated by Pacific Ocean faunal influences is significant because the sole extant species of the Glypheidae, Neoglyphea inopinata Forest & Saint Laurent, 1975, is known only from the west Pacific.

K e y w o rd s : Decapoda, Glypheidae, paleobiogeography, evolution, Eocene, Antar- ctica.

Rodney M. Feldmann [email protected]], Department of Geology, Kent State University, Kent, Ohio, 44242, U.S.A. Andrzej Gaździcki I gazdzick@ twarda.pan.pl], InsĘtut Paleobiologii PAN, ul. Twarda 5 1/55, PL-00-8 I 8 Warszawa, Poland.

Introduction

The La Meseta Formation (Elliot & Trautman L98f) is the Eocene to ?early Oligocene sequence of richly fossiliferous shallow marine deposits exposed in the northern portion of Seymour Island,Antarctic Peninsula (Fig. 1).It comprisesan approximately 800 m thick successionof poorly consolidatedsandstones and siltstoneswith very well preserved micro- and macrofossils (Stilwell & Zinsmeister L992). Anomuran and brachyuran decapod crustaceansare found throughout most of the formation and documenta remarkablydiverse assemblagein such a high latitude setting(Feldmann & Wilson 1988).The purpose of this work is to describe the first macruranremains from the La Meseta Formation. 438 A new palinuran lobster: FELDMANN & GAZDZICKI

Penguin Bay ''fi. * V1 ,1 0 1km

Fig. 1. Map of the northern part of Seymour Island showing the site from which Glyphea reticulata sp. n. was collected(ZPN,12 Sadler Stacks). Arrow of inset shows the location of Seymour Island in Antarctica.

Fig.f. Mew of Seymour Island,looking southwardfrom Cape Wiman (Elliot Ridge). Asterisk denotesthe collecting site (ZPAL 12, Sadler Stacks)' Photo by A' Guździcki,February 1994. ACTA PALAEONTOLOGTCA POLOMCA (4f) (3) 439

The new species of macruran,the palinuran lobster Glyphea reticulata, occurs in the lower units (Telm 1-2) (Sadler 1988)of the La Meseta Formation which crops out on the southside of the east-westtrending Silent Valley (Gaździck't& Tatur t994)near Cape Wiman (Fig. 1). The specimenswere found in carbonatecemented concretions which occur in gray sandy siltstoneand sandstonewith intercalationsof shelly hash at locality ZPAL 12, Sadler Stacks (Fig. 2). The lobsters are associatedwith ńundant cyclostome and cheilostome bryozoans (Guździcki & Hara 1994; Hara in press), numerous brachiopods (Bitner 1996), corals (Stolarski 1996), gastropods,bivalves including large Ostrea andPecten shells, sharkteeth, and shell fragments.Microfossils arerepresented by marine palynomorphs,benthic foraminifera, and ostracods.The age of the lower part of the La Meseta Formation (units Telm 1-2) has been determinedto be early Eocene on the basis of dinoflagellatecysts (Cocozza & Clarke 1992). The lobster collection, representedby two nearly complete carapacesand other fragmentaryremains, is housedin the Instituteof Paleobiology of the Polish Academy of Sciences,Warszawa, abbreviated ZPAL.

Systematics

Order Decapoda Latrellle, 1803 Infraorder Palinura Latrellle, 1803 Superfamily Glypheoidea Winckler, 1883 Family Glypheidae Winckleą 1883 Genus Glyphea von Meyer, 1835 Type species: Palinurus regleyanus Desmarest, 1882 by original designation. Glyphea reticulata sp. n. Fig. 3A-C. HoloĘpe: Specimen ZPN'Cr.IV/1 (Fig. 3A). Ępe horizon and locality: TelmI_f, LaMeseta Formation @ocene), Sadler Stacks, Seymour Island, Antarctica. Etymology: The trivial name alludes to the reticulate pattern of ornamentation developed on the thoracic portion of the cephalothorax which serves to distinguish this species from all others. Diagnosis. - Differs from othet species of Glyphea in having the combination of pustulosehepatic region, small spines along posterior edge of cervical groove, uni- formly fine reticulate sculpture over thoracic portion of carapace, and transverse groove on abdominalterga developed only abaxially. Description. - Cephalothorax moderate size for genus, height about 42Vo length excluding rostrum. Dorsal margin straightor slightly down-curvedanteriorly; poste- rior margin straightto weakly concave dorsally and strongly convex ventrally; poste- roventral margin smoothly convex, greatestheight at about midlength;anteroventral margin straight, sloping posteroventrally,strongly downturned at base of cervical groove.Rostrum and front not preserved. Cervical grooveweakly concaveforward, intercepts dorsum at 65' angleat distance of 367o total length of cephalothorźx'curving anteriorly near base to join antennal 440 A new palinuran lobster: FELDMANN & GAZDZICKI

Fig. 3. Glyphea reticulata sp. n. A. Left lateral view of holotype, ZPN- Cr.IY/I, whitened, showing flattened, slightly distorted carapace, endophragmal skeleton below carapace, and portions of pereiopods, x 1.5' B. Dorsal view, ZPAL Cr.IY/f, unwhitęned, showing the nature of exfoliation of cuticle, x 1.5. C. Rightlateral view,ZPALCr.IYlf , unwhitened, showing abdominal somites 2-6,x 1.5. D. Left lateral view, ZPAL Cr. IY lf , whitened, showing abdominal somites 2-6, x 1.56. E. Enlargement of left lateral view of somite f,ZPAI-Cr.IY/f, whitened, showing details of pleural margin, x 3. groove. Branchiocardiac groove narro% deeply incised, steeply oblique, approaching dorsum atfl" angle, curving abruptly to cross dorsum at63' angle. Postcervical groove as strong as branchiocardiac, approaching dorsum at 8' angle, converging toward ACTA PALAEONTOLOGTCA POLONICA (42) (3) 441 branchiocardiacposteriorly to meet just above inflection in branchiocardiacgroove. Inferior groove concave forward, distinct.Antennar groove extendsparallel to ventral margin. Cephalic region poorly preserved,with at least three longitudinal spinose ridges. Antennal ridge strongest.Hepatic region coarsely pustulose.Prominent, coarse nodes or spines in row posterior to cervical groove, remainder of carapace with finely reticulate,elevated sculpture. Marginal rimbroad, smooth,distinctposteriorly, becom- ing narrowerbut remaining distinct ventrally. Abdominal somitesf-6 preserved.Somites 2 and6 about 1.4times averagelength of somites3-5. Generally smoothtergat surfaces and sculptedpleural surfacesbearing groovęSand with spinosemargins. Somite 2 with smoothtergum aboutas long as wide, strongly archedtransversely, bearingshallow grooveextending from posteriorarticulation anterodorsally, becoming more obscure and disappearingabout 4 mm from point of origin. Tergum separated from pleuron by broad, shallow, arcuate sulcus extending from just above anterior articulation to posterior articulation. Another broad, shallow sulcus more or less extendsparallel to pleural margin dividing pleuroninto smooth,elevated central region and flattenedńm. Pleural margin straightanteriorly and apparentlysmoothly curved posteriorly,bearing ventrally-directed,fine spines at least on anteriorportion. Somites 3-5 similar in configuration, shorter than somite 2, somewhat more broadly archedtransversely, appearing wider than long in dorsal aspect.Terga similar to that of somite f exceptanterodorsally directed groove obscureon somite 5. Pleura with broaderborders, about 40 percentlength of eachpleuron. Pleural marginsof three straightelements separated by small, but distinct, spines;one spine at midlength and one at anteroventralcorner. Somite 6 with generally smooth tergum and very weak groove separatingtergum from smoothpleura. Pleural margin of two straightelements of approximatelyequal length.Telson and uropodsnot preserved. Endophragmalskeleton poorly preserved,represented by somitesPr-P:. Appendagesrepresented by proximal elementsof pereiopods3-5; elongate,slen- der. Height of meri about 0.17 length of element.Surfaces with longitudinal rows of punctaeoverall and single row of small spines ventrally.Terminations of appendages unknown Dimensions.- See Table 1.

Tab1e 1. Measurements, in mm, taken on the holotype and two partypęs of Glyphea reticulata sp. n.

Carapace Specimen CLr CLz CH Holotype ZPAL Cr.IV/l 39.0 f5.0 16.3 ParaĘpeZPALCr.IV/3 c.38 f4.5 r6.6 Abdomen

Lf Hz L: Hr Lą Ls Lo ParaĘpe7PN-Cr.IYl2 10.3 6.7 7.9 7.1 6.9 7.6 10.3

CLI - Carapace length, excluding rostrum; CLZ - Carapace length from posterior to cervical groove; CH - Maximum carapaceheight; L2,H2, etc.- Length and heightmeasurements of the abdominalsomites. 442 A new palinuran lobster: FELDMANN & GAŹDZICKI

Remarks. - The specimensupon which this new speciesis basedinclude two nearly complete carapaces,an abdomen lacking the first somite and the telson, a partial caIapace'a partial abdomęn,a{rd a nearly complete specimen which is crushed and rather poorly preserved.Together, the specimensmake it possible to describe all the elementsnecessary to place the material in the genus Glyphea with confidence.The only generathat might be confusedwith Glyphea are TrachysomaBell and Litogaster von Meyer; however, in both these species the postcervical and branchiocardiac grooves are parallel one another.Quayle (1987) consideredTrachysoma to be the junior synonym of Glyphea;however, that synonymy is not clear and it would be more prudent,at this point, to consider the two generadistinct. Glaessner (1969) recorded occuffences of the genus from New Zealand, Australia, and Germany, as well as England and, althoughnone of thesesouthern hemisphere occurrences is known to us, their existencemust be documentedbefore a definitive judgementcan be made.Until that is done, the differencesin the carapacegroove patternand the degreeof develop- ment of the region of thę mandibulararticulation seem to serve as legitimatepoints of distinction. A combinationof charactersexhibited by this speciesserves to distinguish it from all others.Glyphea reticulątąpoSseSSeS a well developed,entire postcervical groove, lacks an accessory groove, has a relatively coarsely ornamentedhepatic region, and uniformly fine reticulateornamentation over theposterior portion of the carapace.This affay of characters,coupled with the generallyunadorned tergal surfaceson which the transversegroove is only developedon the flanks, renderit unique. Examination of other species of Glyphea, includtng those from Great Britain monographedby H. Woods (I925-L931),Canada and the United States(Feldmann & McPherson 1980),and the SouthernHemisphere (Etheridge, Jr. 1917; J.T. Woods 1957; Taylor 1979; Feldmann 1993; Feldmann et al. 1993) confirm that the most distinctive featureof Glyphea reticulataisthe presenceof thereticulate ornamentation on the thoracic region of the carapacę.ornamentation on other speciestends to range from nearly smoothto pustulose,to scabrous.Work in progresson undescribedspecies from New Zealand and Australia also supportsthe uniquenessof the reticulate or- namentation.Thus, there is little difficulty in distinguishingthis new speciesfrom all othersin the genus. In tęrmsof distributionof decapodcrustaceans, glypheids are moderatelywell-rep- resentedin the Antarctic.Glyfuhea alexandri Taylor, 1979,and G. georgiensisTaylor, 1979,were describedfrom Lower Cretaceousrocks of Alexander Island.in additionto G. australensisFeldmann et al., 1993,from the Campanian-?Maastrichtianof James Ross and Vega islands. Within the rest of thę SouthernHemisphere, there may be aS many as five other species.Glyphea ąrborinsularisEtheridge Jr., I9I7 and G. oculatąJ.T. Woods, 1957 havebeęn describedfrom the Aptian andAlbian, respectively,of Queensland,Australia (J.T.Woods 1957),G. stilwelli Feldmann,1993 was describedfrom Paleocenerocks of New Zealand(Feldmann 1993), andtwo otherspecies, as yet undescribed,have been collected from the Cretaceousof Australia and the Eocene of New Zealand.Thus. the number of species from the SouthernHemisphere rivals that of the Northern Hemis- phere. ACTA PALAEONTOLOGTCA POLONTCA (42) (3) 443

The Glypheidae are represented by a single extant species, Neoglyphea inopinata Forest & Saint Laurent, 1975. This species, collected at depths of about 200 m on a substratum of fine sand, mud, and shell material (Forest, Saint Laurent & Chace, Jr. 1976), is known only from the South China Sea. Thus, the sole relict of a taxon that was much more widely distributed in the Mesozoic and early Cenozoic survivęs in the west-central Pacific. The depth at which N. inopinata |ivęs is much greater than the probable depth at which Glyphea reticulata lived. It is likely that all the specimens of G. reticulatą represent molted remains. None of the specimens consists of complete, articulated skeletons and in two of the speci- mens in which the carapace is present, ZPN, Cr. IV/1 andZPALCr.IYl4, there is a strong suggestion of molting. In both specimens, the endophragmal skeleton is 'Salter's displaced ventrally from the cephalothorax, which is typical of position'. Similar orientations of internal skeleton to carapace have been interpreted to be molts in other glypheids. Glyphea robusta Feldmann & McPherson, 1980, from the early Jurassic_early Cretaceous of Arctic Canada and G. ąustrąlensis Fęldmann et al., 1993, from the Campanian-?Maastrichtian of James Ross and Vega islands, Antarctica, have been preserved in the same position. In the latter example, distortion of the carapace material further suggested that the carupace was soft and supple; additional evidence of molting. The carapace of the holotype of G. reticuląta is flattened and somewhat distorted which reinforces the interpretation. This new species occurs in association with another decapod, ?Calliąna,','4 Sp. Recent detailed study of the Callianassidae and Ctenochelidae (Manning & Felder, 199I) has established several key characters of the chelipeds that are useful in generic placement; however, most of the diagnostic characters are to be found on the merus and carpus. These elements are not preserved on the specimens at hand and, therefore, generic placement must be considered tentative. Nonetheless, the specimens are important because most callianassids occur in inner sublittoral or littoral habitats which provides documentation for the bathymetric conditions at the depositional site of Glyphea reticulątą.

Acknowledgements

The logistic support provided by the Instituto Anti{rtico Argentino and Fuerza AóreaArgentina in the austral summer of 1993-1994, during the Argentine-Polish field party on Seymour Island is gratefully acknowledged.The manuscriptwas carefully reviewed by Gale A. Bishop, J.S.H. Collins, and Renó Fraaye. Their suggestions were most useful. This work was supported by National Science Founda- tion grant OPP95f6f52 to Feldmann. Contribution 581, Department of Geology, Kent State Univer- sity, Kent, ohio M24f' U.s.A. Photographs were prepared by GruŻynaDziewińska, Instytut Paleo- biologii PAN, Wars ztw a.

References

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Nowy gatunek Glgpheą (Decapoda: Palinura) z eoceńskiej formacj i La Meseta Wyspy Seymour, Antarktyka

RoDNEY M. FELDMANN i ANDRZEI GAŹDZICKI

Streszczenie

Zbogatych w skamieniałościutworów formacji La Meseta z Wyspy Seymour (PóŁ wysep Antarktyczny) opisano nowy gatunekdziesięcionoga z rodzaju Glyphea (De- capoda: Palinura). Zna|ezione okazy reprezenĘą zapewne wylinki. Potwierdza to ',pozycjaSaltera'', wyraiLa1ącasię odspojeniemszkieletu endofragmalnegood głowo- tułowia,zaobserwowana w przypadkudwóch najbndziej kompletnych okazów.Nowy gatunekGlyphea reticulatajestjednym z najmłodszychwiekowo znanychprzedsta- wicieli tego rodzaju.