Australocaris Poore & Collins, 2009, gen. nov.

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).新属Australocaris（gen. nov.） 模式种：本文指定Australocaris pinjarup 新种（sp. nov.）。 鉴别特征：头胸甲光滑，具短且轮廓模糊的颈沟。额剑呈针形，细长，侧缘具细齿，长度为眼柄的3倍，与头胸甲等长，与清晰的侧胃脊相连；眼上棘（位于侧胃脊前端且额剑基部的棘）显著；侧胃脊除前端的眼上棘外无棘；亚中胃脊存在但不明显；中胃脊呈弱脊状；后颈脊缺失。 腹部第1体节侧突发达；第2侧突宽阔，前缘圆润，腹面平坦，后缘圆润；第3—5侧突后缘圆润。眼柄呈圆柱形，可活动；角膜无色素。触角外肢（scaphocerite）超出触角柄部，具基内棘及下缘棘。第3颚足外肢在鞭毛基部无明显弯折。第2—4步足上方无侧鳃（pleurobranchs）；侧足鳃（podobranchs）与关节鳃（arthrobranchs）发达；第2颚足至第4步足具上肢（epipods）。第1步足（螯足）对称，掌节侧扁且宽阔，背、腹缘均具脊；腕节—指节的背、腹缘具强棘。第3—5腹肢具内附肢（appendix interna）。雄性第1腹肢极小；雄性第2腹肢无雄性附肢（appendix masculina）。尾肢外肢具横缝。 词源：由Australia与希腊语karis（意为虾，阴性）组合而成。 讨论：遗憾的是，模式种仅存的标本为一只发育阶段不明的雄性个体。该标本具一对简单的第1腹肢，且第2腹肢无雄性附肢。这些附肢可能在后续龄期发育。尽管如此，额剑及相关胃脊的独特形态、具棘的长触角外肢，以及螯足的形态，均将该种与所有其他螯虾科（Axiidae）物种区分开来，因此建立新属是合理的。 Poore（1994）的检索表将该种归入Calocarides Wollebaek, 1908属（该属特征：尾肢外肢具缝、具上肢、具内附肢、无侧鳃、触角外肢发达、头胸甲光滑、眼柄长度不超过额剑的一半、眼弱色素化）。二者的差异在于：本新属雄性第1腹肢极小（但该特征不具有属级分类意义——详见下文Paraxiopsis的讨论），且本新种具雄性附肢（而Calocarides属物种具该结构）。Calocarides属已由Kensley（1996c）进行了分类修订。该属11个物种的胃脊均或多或少具棘；而本新种的胃脊除眼上棘及额剑齿外，其余部分均不明显且无棘。Calocarides属物种的第1步足不对称、狭窄、呈圆柱形且细长，齿仅集中于掌节和指节的背缘；而本新种的螯足对称、宽阔且侧扁，腕节—指节的背、腹缘均具强棘。该螯足形态将本新属与所有其他螯虾科（Axiidae）属区分开来。 无雄性附肢的螯虾科（Axiidae）属包括Axiorygma Kensley & Simmons, 1988、Bouvieraxius Sakai & de Saint Laurent, 1989（部分物种）、Parascytoleptus Sakai & de Saint Laurent, 1989以及Paraxius Bate, 1888，但本新属与这些属形态差异显著。除Bouvieraxius属外，其余各属均为单型属。 具棘的触角外肢为螯虾科（Axiidae）所特有，但在非亲缘关系的Neaxius acanthus Milne-Edwards, 1878（Strahlaxiidae科）中也可见类似的棘状结构。