Marylyreidus punctatus (Rathbun, 1935) Van Bakel & Guinot & Artal & Fraaije & Jagt, 2012

Van Bakel, Barry W. M., Guinot, Danièle, Artal, Pedro, Fraaije, René H. B. & Jagt, John W. M., 2012, A revision of the Palaeocorystoidea and the phylogeny of raninoidian crabs (Crustacea, Decapoda, Brachyura, Podotremata) 3215, Zootaxa 3215 (1), pp. 1-216 : 87

Marylyreidus punctatus (Rathbun, 1935) n. comb.

Notopocorystes punctatus Rathbun, 1935b: 8 .

Notopocorystes parvus Rathbun, 1935b: 48 .

Raninella mucronata Rathbun, 1935b: 50 .

( Fig. 25A–E )

Material examined. One incomplete carapace, MAB k. 2884 (male), with well-preserved pleurites, thoracic sternum and remains of appendages, one fragmentary carapace ( MAB k. 2891), plus one carapace with well-preserved pleurites and thoracic sternum ( MGSB 75297, ex Àlex Ossó-Morales Collection). All from the upper Albian-lower Cenomanian (Pawpaw Formation), Tarrant County, Texas, U.S.A.

Emended description. Sternite 3 large, onion shaped, well separated from anterior sternites, narrower than sternite 4, from which it is separated by distinct indentations/notches at both sides, but not by groove on sternal plate. Sternite 4 of constant width, slightly longer than wide, its anterior part not extended laterally or connected to posterior corner of pterygostome. Gynglyme receiving P1 condyle distinctly visible in dorsal view; episternite 4 broadening posteriorly to twice sternite 4 width, forming 2 triangular plates. Sternite 5 distinctly wide, anterior part markedly extended between P1, P2, thus effectuating distinct separation of 2 anterior pereiopods; this lateral extension connected to anterior thoracic pleurite. Posterior part of sternite 5 much narrower, equalling sternite 4 width. Posterior margin of lateral projection of sternite 5 concave, corresponding to P2 coxa. Episternite 5 slightly raised, separated from anterolateral sternite 5 by deep gutter; P2 gynglyme visible in dorsal view. Sternite 5 medially forms weak cavity between raised episternites 5. Mxp3 long; coxa moderate in size, not well extended anterior to P1 coxa, intercalated between anterior portion of sternite 4, pterygostome, with sharp extension intercalated between sternites 3, 4; surface flabelliform, posterolaterally curved inwards to branchial chamber. Mxp3 basis with rounded proximal side; ischium long, widening distally with sinuous lateral side matching curvature of exopod; merus long, with weak medial depression. Mxp3 exopod long, slender, sinuous, tip slightly beyond ischium of endopod. Pterygostome tumid, with blunt crest and groove.

Remarks. Discovery of two specimens with preserved ventral characters necessitates an amendment of the description. The dorsal carapace was described by Rathbun (1935b: 48) and Haj & Feldmann (2002: 474).

Figures

FIGURE 25. Marylyreidus punctatus (Rathbun, 1935b) n. comb. (Lyreididae, Marylyreidinae n. subfam.), upper Albianlower Cenomanian (Pawpaw Formation), Tarrant County, Texas (U.S.A); A, D, MAB k. 2884 (male); right lateral view, and ventral view showing thoracic sternum and bases of appendages; B, C, E, MGSB75297 (ex Àlex Ossó-Morales Collection; indeterminate sex); left lateral view showing exposed pleurites (thoracic sternum slightly displaced); dorsal view of carapace, and ventral view showing thoracic sternum and bases of appendages. aP1, arthrodial cavity of P1; P2, P3, pereiopods 2, 3; pl5, pl6, pl7, exposed pleurites 5, 6, 7. Scale bars: 5mm.