Hoploparia M’Coy, 1849

Tshudy, Dale M., Hyžný, Matúš, Veselská, Martina Kočová & Jagt, John W. M., 2022, Taxonomic revision of the extinct clawed lobster genus Oncopareia Bosquet, 1854 (Decapoda, Astacidea, Nephropidae), Palaeontologia Electronica (a 20) 25 (2), pp. 1-31 : 18-19

Genus Hoploparia M’Coy, 1849

Type species. Astacus longimanus Sowerby, 1826 , by the subsequent designation of Rathbun (1926).

Diagnosis (after M’Coy, 1849, pp. 175–176). Carapace minutely granulose, oblong, tumid, slightly compressed, a little deeper than wide, ending in front in a strong sharp rostrum, the sides of which are strongly carinate and smooth, or with few very minute teeth; beneath the orbits the cheeks are prolonged forwards about half the length of the rostrum.

Diagnosis (after Feldmann et al., 2016, p. 16). Subcylindrical carapace smooth; rostrum long, with suprarostral spines; supraorbital spine present; scaphocerite present; subdorsal carina present; cervical groove and postcervical groove well-developed, postcervical groove extending from midline to about midheight of carapace where it joins hepatic groove to encircle adductor testis muscle attachment; branchiocardiac groove weak; strong heterochely of pereiopod 1; major chelipeds with fingers with strong, domal denticles on occlusal surfaces; minor chelipeds with finer, spinose denticles on occlusal surfaces; pereiopods 2 and 3 chelate; terga smooth or weakly ornamented; subrectangular telson; exopodite of uropods with diaeresis.

Diagnosis (after Tshudy et al., 2018, p. 174). Rostrum long, spinose. Postcervical groove well impressed over most of length; becomes subtler as it extends anteriorly toward cervical groove. Branchiocardiac groove (dorsally) usually present. Ventral extension of branchiocardiac groove typically extends to hepatic groove. Urogastric groove typically absent. Cervical groove well impressed; extends from level of orbit to junction of hepatic and antennal grooves. Median carina typically absent. Submedian carina present on a few species. Subdorsal carina present. Supraorbital spine present, typically followed by supraorbital carina. Postorbital spine typically present; gastrolateral and hepatic spine typically absent. Antennal carina absent, short, or extending to near cervical groove. Thoracic region lacks carinae. Pleonal terga unornamented, mostly unsculptured; typically with a narrow transverse furrow along posterior margin. Pleura elongate, typically cordate, ending in a point. Telson surface with a pair of submedian ridges converging posteriorly. Telson without lateral spines but with posterolateral spines. Scaphocerite present. Claws typically unequal; upper and lower surfaces lacking carinae. Exoskeleton generally granulated.

Remarks. Hoploparia was erected by M’Coy (1849) for fossils that generally resembled Homarus but had a more sculptured (grooved, locally inflated, etc.) and ornamented carapace. In fact, the name Hoploparia refers to the lobster’s “spiny cheeks”, the locally inflated and ornamented regions on the anteroventral sides of the cephalothorax. Homarus lacks these locally inflated “cheeks” and is less spiny. M’Coy’s diagnosis, reprinted here, distinguished the type species, Hoploparia longimana , from Homarus .

Hoploparia is readily distinguished from Oncopareia in the nature of the chelipeds and pleon. Claws are never pectinate in Hoploparia and pleura 3-5 in Oncopareia are characteristically quadrate, not cordate and pointed as in Hoploparia .