Oxydromus Grube, 1855

Hiro, Uchida, omi, Lopéz, Eduardo & Sato, Masanori, 2019, New Hesionidae (Annelida) from Japan: Unavailable Names Introduced by Uchida (2004) Revisited, with Reestablishment of their Availability, Species Diversity 24, pp. 69-95 : 71-72

Genus Oxydromus Grube, 1855

Oxydromus Grube, 1855: 98 ; Villalobos-Guerrero and Harris 2012: 23 .

Ophiodromus Sars, 1862: 87 ; Pleijel 1998: 137–143, figs 31– 33; Uchida 2004: 36–39.

Remarks. The synonymy between Oxydromus Grube, 1855 and Ophiodromus Sars, 1862 ( Pleijel 1998) was finally resolved with Oxydromus reinstated over Ophiodromus by Villalobos-Guerrero and Harris (2012). Therefore, the following seven species that Uchida (2004) originally described as Ophiodromus are here described as valid new species of Oxydromus .

Oxydromus brevipodius Uchida , sp. nov. [New Japanese name: Koashi-haya-otohime] ( Fig. 2 )

Ophiodromus brevipodius Uchida, 2004: 43–45 , fig. 6 (unavailable specific name, without explicit fixation of name-bearing types).

Oxydromus brevipodius (specific name unavailable): Villalobos-Guerrero and Harris 2012: 24 (referred in check list); Rizzo and Salazar-Vallejo 2014: 280 (in key).

Type material. Holotype: mature female (NSMT-Pol H-692), off Shionomisaki Cape, Kushimoto , Wakayama Prefecture (33°24′22″N, 135°45′55″E), dredged from 200 m depth, coll. S. Nagai, 21 January 1990.

Diagnosis. Holotype 15 mm long for 50 chaetigers, body colorless after preservation. Lateral antennae one and a half as long as the prostomium; median antenna a quarter as long as lateral ones; palps bi-articulated, as long as antennae ( Fig. 2A ); eyes circular, pale brown, anterior eyes larger than posterior ones. Parapodia sub-biramous ( Fig. 2 B–D ). Notopodial cirrophores with remarkable constriction at their middle and cylindrical distal part ( Fig. 2E ); cirrostyles more distinctly articulated in their distal half ( Fig. 2C, D ); small fascicle of 3–4 forked notochaetae, with subdistal tine less than half as long as distal one ( Fig. 2F ). Neuropodial lobes short and very stout ( Fig. 2D ); compound chaetae with long, finely serrated blades ( Fig. 2G–L ).

Etymology. The specific name refers to the distinctly short size of neuropodial lobes compared with other cogeneric species.

Remarks. The detailed description of the holotype was presented in Uchida (2004). Oxydromus brevipodius sp. nov. is similar to O. pallidus ( Claparède 1864) , from the Mediterranean Sea ( Claparède 1864) and common in western Europe ( Parapar et al. 2004), and to O. guanicus ( Hoagland 1919) , from the Caribbean Sea ( Hoagland 1919), in possessing short, sub-biramous parapodia. However, the new species clearly differs from O. pallidus in (1) distal articulation of palps, in contrast to proximal one in O. pallidus ; (2) palps as long as the lateral antennae, in contrast to those shorter than lateral antennae in O. pallidus ; and (3) larger eyes (especially in the posterior pair) (see Parapar et al. 2004). The new species differs in turn from O. guanicus in (1) the presence of notochaetae, in contrast to the lack of the same in O. guanicus ( Rizzo and Salazar-Vallejo 2014) ; (2) the constriction proximally situated in notopodial cirrophores, in contrast to that distally situated in O. guanicus ; and (3) longer lateral antennae and palps ( Uchida 2004).

Figures

Fig. 2. Oxydromus brevipodius sp. nov., holotype (NSMT-Pol H-692). A, dorsal view of the anterior body. B, anterior view of right parapodium 21 (with dorsal cirrus of short type). C, anterior view of right parapodium 22 (with dorsal cirrus of long type). D, posterior view of right parapodium 21. E, enlarged anterior view of notopodium of the same. F, notochaeta. G–I, supra-acicular neurochaetae: G, inferior; H, median; I, superior. J–L, sub-acicular neurochaetae: J, superior; K, median; L, inferior. Scale bars: 1mm for A; 0.5mm for B, C; 0.2mm for D; 0.1mm for E; 0.02mm for F; 0.05mm for G–L.