Australocaris, Poore & Collins, 2009

Poore, Gary C. B. & Collins, David J., 2009, Australian Axiidae (Crustacea: Decapoda: Axiidea), Memoirs of Museum Victoria 66 (2), pp. 221-287 : 238

Australocaris gen. nov.

Type species. Australocaris pinjarup sp. nov., here designated.

Diagnosis. Carapace smooth; with weakly defined short cervical groove. Rostrum styliform, elongate, laterally denticulate, 3 times as long as eyestalks, level with carapace, continuous with definite lateral gastric carinae; supraocular spines (spine at anterior end of lateral gastric carina and base of rostrum) prominent; lateral gastric carina unarmed except for anterior supraocular spine; submedian gastric carina present, obsolete; median gastric carina as weak ridge; postcervical carina absent. Abdominal somite 1 pleuron produced; pleuron 2 broad, anterioirly rounded, ventrally flat, posteriorly rounded; pleura 3–5 posteriorly rounded. Eyestalk cylindrical, articulating; cornea unpigmented. Antenna, scaphocerite extending beyond antennal peduncle, with basal mesial spine and spines on lower margin. Maxilliped 3 exopod not clearly bentatbaseofflagellum. Pleurobranchs absent above pereopods 2–4; podobranchs and arthrobranchs well developed; epipods present on maxilliped 2 to pereopod 4. Pereopods 1 symmetrical, with propodus laterally flattened, broad, carinate on upper and lower margins; carpus-dactylus upper and lower margins with strong spines. Pleopods 3–5, appendix interna present. Pleopod 1 of male minute. Pleopod 2 of male without appendix masculina. Uropodal exopod with transverse suture.

Etymology. A combination derived from Australia and karis (Greek), a shrimp (feminine).

Remarks. It is unfortunate that the only individual of the type species is a male of uncertain development. It has a pair of simple pleopods 1 and lacks an appendix masculina on pleopod 2. These limbs may develop at a later instar. Nevertheless, the unique form of the rostrum and associated gastric carinae, the long spinose scaphocerite, and the form of the chelipeds distinguish the species from all other axiids and a new genus is justified. Poore’s (1994) key leads this species to Calocarides Wollebaek, 1908 (uropodal exopod with suture, epipods present, appendix interna present, pleurobranchs absent, scaphocerite well developed, carapace smooth, eyestalks not more than half length of rostrum, eyes weakly pigmented). Differences are in the absence of the male pleopod 1 (minute in the new genus but not considered of generic importance—see discussion of Paraxiopsis below) and presence of the appendix masculina (absent in the new species). Calocarides was reviewed by Kensley (1996c). The gastric carinae of all its 11 species are more or less armed; apart from the supraocular spine and rostral dentition, gastric carinae in the new species are obsolete and unarmed. The first pereopods of species of Calocarides are asymmetrical, narrow, cylindrical and linear with teeth concentrated on the upper margins of the propodus and dactylus while in the new species the chelipeds are symmetrical, broad, flattened, with strong spines on the upper and lower margins of the carpus-dactylus. These chelipeds set the new species apart from all other axiid genera. Genera without an appendix masculina are Axiorygma Kensley and Simmons, 1988 , Bouvieraxius Sakai and de Saint Laurent, 1989 (some species), Parascytoleptus Sakai and de Saint Laurent, 1989 , and Paraxius Bate, 1888 but the new genus bears little resemblance to these genera. All except Bouvieraxius are monotypic.

The spinose scaphocerite is unique to axiids but similar spination is seen in the unrelated Neaxius acanthus Milne-Edwards, 1878 ( Strahlaxiidae ).