Palaeocorystoidea

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 : 167

Palaeocorystoidea versus Raninoidea De Haan, 1839

Extant Raninoidea are discussed and listed by e.g. Bourne (1922b), Monod (1956), Gordon (1963, 1966), Gomes Corrêa (1970), Griffin (1970), Serène & Umali (1972), Hartnoll (1979), Goeke (1980, 1981, 1984, 1986), Davie (1989), Werding & Müller (1990), Guinot (1993b), Guinot & Bouchard (1998), Dawson & Yaldwyn (1994, 2000, 2002), Guinot & Quenette (2005), Ahyong et al. (2009) and Guinot et al. (in press).

Carapace.

‒ Carapace areolated and generally with cervical groove in Palaeocorystoidea , indistinct in Camarocarcinidae (not areolated, obsolete cervical groove in Raninoidea ).

‒ Anterolateral margin of carapace with multiple teeth or tubercles in Palaeocorystoidea , fewer, however, in Camarocarcinidae (unarmed or with a single tooth or two teeth in Raninoidea ).

Pterygostome, endostome and mxp3.

‒ Coxa of mxp3 large, flabelliform in Palaeocorystoidea (small and flat in Raninoidea ).

‒ Antero-lateral corner of sternite 4 not in contact with pterygostome in Palaeocorystoidea , large coxa of mxp3 intercalated between thoracic sternum and pterygostome, presence of Milne-Edwards openings (sternum/ pterygostome junction present, absence of Milne-Edwards openings in Raninoidea , except Marylyreidinae n. subfam.).

‒ Pterygostome with groove and blunt crest in Palaeocorystoidea (groove or crest absent in Raninoidea ).

Appendages.

‒ Pereiopods equally spaced, putatively not separated by sternal extensions in Palaeocorystoidea (sterno-pleural extensions separating P1 and P2, and P2 and P3, thus pereiopods unequally spaced, in Raninoidea ).

Thoracic sternum.

‒ No exposed pleurites in Palaeocorystoidea (pleurites 5‒7 partially exposed (‘gymnopleurity’) and calcified in Raninoidea ).

‒ Sterno-pleural extensions absent (present between P1 and P2 and between P2 and P 3 in Raninoidea ).

‒ Spermathecal apertures large, oval, separate, thus normal podotreme condition in Palaeocorystoidea (embedded in sternite 7, small, close to each other, deeply recessed in Raninoidea , rarely otherwise).

Abdomen.

‒ Male abdomen rather long, telson reaching sternite 4, completely flexed under the body and locked in Palaeocorystoidea (short and posterior, telson only reaching sternite 6, not completely flexed and not locked in Raninoidea , except Lyreididae ).

Abdominal holding.

‒ Paired sternal tooth (double peg) on episternite 5 in Palaeocorystoidea (absent in Raninoidea , except in Lyreididae , with two teeth at tip of a short or long hook-like projection formed by extended episternite 5).