Heardaxius Sakai, 2011

Poore, Gary C. B., 2015, Rediagnosis of Callianideidae and its genera (Crustacea: Decapoda: Axiidea), and description of a new species of Heardaxius Sakai, 2011, Zootaxa 3995 (1), pp. 229-240 : 233

Heardaxius Sakai, 2011

Heardaxius Sakai, 2011: 533 .

Type species. Mictaxius salvati Ngoc-Ho, 2005 (by original designation and monotypy).

Diagnosis. Hermaphroditic. Rostrum obsolete. Linea thalassinica complete or nearly so. Thoracic sternite 7 with narrow anterior part, slightly separating cushion-like coxae of pereopods 4. Pleomere 1 tergite with flat broad anterior part almost as wide as posterior part. Eyestalks flattened, contiguous, each with acute apex; pigmented cornea dorsal. Antennal scaphocerite minute and articulating. Maxilliped 3 merus without distal tooth, exopod reduced, with toothed crista dentata, ischium and merus without brush of stiff setae. Pereopods 1 similar or slightly dissimilar. Pereopod 3 propodus about 1.5 times as long as broad, with distal spiniform seta. Pereopod 4 propodus without distal spiniform seta. Pereopod 5 simple, dactylus closing on distal spiniform seta on propodus. Setal-rows on anterolateral carapace, pleomere 1 and pleomere 6 (2 rows). Pleopod 1 2-articled. Pleopod 2 with elongate appendix masculina with long terminal setae, appendix interna a fused thumb-like extension. Pleopods 2–5 rami without marginal filaments. Uropodal endopod without transverse row of short spiniform setae; exopod ovate, without dorsal plate.

Included species. Heardaxius rogerbamberi n. sp.; H. salvati ( Ngoc-Ho, 2005) (ex Mictaxius ).

Remarks. Sakai (2011) erected the new genus Heardaxius within Thomassiniidae including only the type species. He differentiated it from Mictaxius Kensley & Heard, 1991 only on the presence (in Mictaxius ) and absence (in Heardaxius ) of a uropodal dorsal plate. His diagnosis included pleopodal features of the male without acknowledging that the type species was hermaphroditic, with gonopores on coxae of pereopods 3 and 5 and an appendix masculina on pleopod 2 of an ovigerous female ( Ngoc-Ho 2005). His diagnosis also erred in stating that pereopod 5 was simple or subchelate (it is always simple, although a spiniform seta gives the appearance of it being subchelate) and that setal-rows are present on pereopods 2–4 (none exist).

Nevertheless, Mictaxius salvati and the new species do differ from the species currently in Mictaxius , M. arno and M. thalassicola .