Calastacus Faxon, 1893

Poore, Gary C. B. & Collins, David J., 2009, Australian Axiidae (Crustacea: Decapoda: Axiidea), Memoirs of Museum Victoria 66 (2), pp. 221-287 : 247-248

Calastacus Faxon, 1893

Calastacus Faxon, 1893: 194 . — Schmitt, 1921: 112. — de Saint Laurent, 1972: 353. — Sakai and de Saint Laurent, 1989: 59. — Kensley, 1989: 961. —Kensley, 1996: 158, 159.

Calocaris (Calastacus) . — Alcock, 1901: 191. — Borradaile, 1903: 539. — De Man, 1925b: 115.

Type species. Calaxius stilirostris Faxon, 1893 , by monotypy.

Diagnosis. Carapace smooth; cervical groove visible laterally over most of distance to anterolateral margin. Rostrum spine-like, laterally weakly dentate, longer than eyestalks, depressed below level of carapace, continuous with lateral carinae; supraocular spines prominent; lateral carina weak; submedian carina absent; median carina smooth; postcervical carina absent. Abdominal somite 1 pleuron triangular; pleuron 2 posteriorly rectangular; pleura 3–5 posteriorly rounded.Eyestalk cylindrical, articulating; cornea unpigmented. Antenna, scaphocerite short. Maxilliped 3 exopod not clearly bent at base of flagellum. Pleurobranchs absent above pereopods 2–4; podobranchs rudimentary on maxilliped 3–pereopod 3, arthrobranchs present; epipods present on maxilliped 2 to pereopod 4. Pereopods 1 asymmetrical, with propodus cylindrical; propodus with spine on upper margin. Pereopods 3–5 propodi with transverse rows of robust setae; dactyli 3 and 4 elongate; dactylus 5 elongate. Pleopods 3–5, appendix interna present. Hermaphroditic. Pleopod 1 article 1 flattened; article 2 subtriangular, two-thirds length of first, folded longitudinally, posterior part distally lobed, anterior part larger, broader, with short appendix interna. Pleopod 2 endopod article 2 elongate, twice length of article 1, mesial margin straight, with basal digitiform appendix interna, appendix masculina divided into 2 equal parts bearing rows of strong setae. Uropodal exopod with transverse suture. Telson without lateral teeth, without posterolateral robust setae; apex deeply rounded and continuous with lateral margins.

Remarks. Calastacus is a genus of six species, C. stilirostris Faxon, 1893 from the central eastern Pacific, C. laevis de Saint Laurent, 1972 from the eastern Atlantic and Mediterranean, C. colpos Kensley, 1996 and C. mexicanus Kensley, 1996 from the Gulf of Mexico ( Kensley, 1996e), C. crosnieri Kensley and Chan, 1998 and C. inflatus Komai, Lin and Chan, 2009 from the north-western Pacific. The genus was diagnosed by de Saint Laurent (1972) whose concept has been followed by later authors. The genus differs from Ambiaxius only in the characteristic pleopods 1 and 2. Pleopod 1 is more elongate than in Ambiaxius and pleopod 2 has a long second segment on the endopod. A seventh species, first from the Indian Ocean, is described below.