Asteronyx longifissus Döderlein, 1927

Granja-Fernández, Rebeca, Hendrickx, Michel E., Rangel-Solís, Pedro Diego & López-Pérez, Andrés, 2023, Deep-sea Ophiuroidea (Echinodermata) collected during the TALUD cruises in western Mexico, Zootaxa 5259 (1), pp. 1-71 : 13

Asteronyx longifissus Döderlein, 1927

Fig. 1A‒F

Asteronyx longifissus Döderlein, 1927: 65‒68 , pl. 7, figs. 1‒3.— A.M. Clark 1965: 68.— Hendler 1996: 123‒125, fig 7.2; 2018: 194‒198, fig. 1.

Material examined. 164 individuals at five stations. TALUD VIII, Sta. 11, 2 ind. (ICML-EMU-11108); Sta. 20, 1 ind. (ICML-EMU-11095). TALUD XV, Sta. 20, 159 ind. (ICML-EMU-11098); Sta. 23, 1 ind. (ICML-EMU-11109); Sta. 24, 1 ind. (ICML-EMU-11699).

Comparative material. Syntypes, 324 ind.: USNM E4061 , USNM E4067 , USNM E4069 , USNM E4076 , USNM E4081 , USNM E4096 , USNM E4109 , USNM E4112 , USNM E4117 , USNM E4118 , USNM E4120 , USNM E4121 , USNM E4242 , USNM E4246 (Supplementary file 2) .

Description (ICML-EMU-11699). DD = 16 mm. Disc pentagonal, flat, indented interradially. Dorsal disc with thickened skin, lacking scales. RS multilayered, very prominent distally, almost reaching the center of the disc ( Fig. 1A ). Ventral interradii entirely covered by integument with some granule-shaped epidermal ossicles proximally. Genital slits oval, restricted to middle-distal part, elongate, covering approximately 3/4 of the interradius ( Fig. 1B ). OSh broader than long, rounded triangular. Madreporite not evident. AdSh broader than long, rectangular with rounded edges, separated by integument. Jaws bearing 8‒9 papillae at each side; OPa 4‒5, spiniform, elongated, separated; TPa four at jaw tips, spiniform, larger than OPa, separated. Teeth several, similar to TPa ( Fig. 1C ). Arms entirely covered by integument, coiled, gradually narrowing distally ( Fig. 1D ). LAP located on the ventral lateral side of vertebrae, short and rounded, prominent ( Fig. 1E ). First and second tentacle pores outside the mouth lacking ArSp; third to eight pores with one ArSp with serrated tip; subsequent pores with 2‒3 ArSp, hook-shaped, serrated, gradually reaching up to six in the middle of the arm; distal tentacle pores with four ArSp, ventralmost ArSp elongated. TSc lacking ( Fig. 1E ). Color pattern yellowish-brown (ethanol preservation) ( Fig. 1A‒F ).

Habitat and distribution. From Oregon, USA, to Northern Mexico; 265‒ 1,800 m depth ( Döderlein 1927; Maluf 1988; see Remarks). Associated with sea pens ( Duffy et al. 2014). The material examined was collected off western Baja California Sur and in the southern Gulf of California; 530‒ 1,150 m depth.

Remarks. Examination of the TALUD specimens and the type material of this species demonstrated that the oral shields can be partially or completely concealed or can be completely visible. Moreover, some specimens can have radial shields almost reaching the center of the disc or cover 3/4 of the diameter of the disc; this could be an artifact caused by preservation because of potential contraction of the soft disc, thus modifying the appearance of the radial shield coverage (pers. comm. Sabine Stöhr, 2022). Asteronyx longifissus has been previously recorded in Mexico only for western Baja California Sur and Guerrero ( Honey-Escandón et al. 2008). Material from Guerrero is deposited at ICML-UNAM (ICML-UNAM 3.140.2, Isla de Ixtapa) and was examined. Morphological differences such as radial shields not multilayered, minute spines in the dorsal disc, and OPa not granule-like were observed. We conclude that the material from Guerrero does not correspond to A. longifissus but probably to a species new to science, and this record should be considered invalid. The discovery of A. longifissus during the Gulf of California cruises is a first for this area. This species is now known to range as far north as 25º56′N. Due to its northern affinity and the invalidation of the record in Guerrero, we suggest that A. longifissus distribution is probably limited to temperate waters in the northern American Pacific.

Figures

FIGURE 1. Asteronyx longifissus Döderlein, 1927 (ICML-EMU-11699, DD = 16 mm). A, Dorsal disc; B, Ventral disc; C, Mouth; D, Dorsal arm; E, Ventral arm; F, Dorsal view. Asteronyx loveni Müller & Troschel, 1842 (ICML-EMU-11111, DD = 23 mm). G, Dorsal disc; H, Ventral disc; I, Mouth; J, Dorsal arm; K, Ventral arm; L, Middle ventral arm; M, Dorsal view.