Iluocoetes Jenyns, 1842

Matallanas, Jesús & Corbella, Cecília, 2012, Redescription of Iluocoetes Jenyns, 1842; proposal of a new genus, Argentinolycus, for Iluocoetes elongatus (Smitt, 1898), and description of Patagolycus melastomus gen. et sp. nov. (Teleostei, Zoarcidae), Zootaxa 3296, pp. 1-18 : 5-6

Redescription of Iluocoetes Jenyns, 1842

( Figs. 1 , 2 & 10 ; Tables 2−4)

Diagnostic characters found in the holotype (+radiographs): Submental crests present, not fused anteriorly; neurocranium elongate, narrowed; frontal bones fused totally with no trace of a suture; frontal corner squared; frontal ramus long; sphenotic and parietal separated by pterotic; parietal bones meeting in the mid-line; parasphenoid wing height high; ceratohyal −epihyal juncture smooth; five branchiostegal rays; posterior hyomandibular ramus elongate; palatal arch well developed; posttemporal ventral ramus well developed; scapular foramen enclosed by bone; scapular strut present; four notched radials (=actinosts); postcleithrum present; dorsal fin-rays 85 (last 7 counted from dorsal-fin pterygiophores); anal-fin rays, 71 (last 10 counted from anal-fin pterygiophores); pectoralfin rays 18; pelvic bone present; vertebrae asymmetrical (21+68=89); ribs on 4−21 abdominal vertebrae; one epural; dorsal-fin origin associated with vertebrae 4; oral valve well developed; gill slit extending ventrally to lower end of pectoral-fin base; gill rakers blunt; pyloric caeca nub-like; scales, palatine and vomerine teeth present; oral cavity pale; peritoneum, black; a blurred brown band between the anteroventral edge of the eye and the upper jaw.

All these characters are present also in the other specimens of I. fimbriatus examined, and additional diagnostic characters of Iluocoetes based on cleared and stained specimens of I. fimbriatus for anatomical study, are the following ( Fig. 1 a, b): frontal and parasphenoid not separated by pterosphenoid; supraoccipital −exoccipìtal articulation excluded by epioccipitals; supratemporal commissure and occipital pores absent ( Fig. 1 b); ascending rami of the parasphenoid reaches the upper margin of the trigeminofacialis foramen; intercalar well developed, not reaching prootic ( Fig. 1 a); suborbital bones 8−9, canal with 7 pores; postorbital pores 1 and 4; posterior nasal pore single; cartilaginous basal plate of pectoral girdle with three foramina; vertebrae asymmetrical (19−21+64−77=83− 97); dorsal-fin origin associated with vertebrae 2−4; oral valve well developed; gill rakers blunt; pelvic-fin rays ensheathed; squamation extensive, but head and pectoral-fin base and axil scaleless; lateral line mediolateral, palatine teeth 9−23; vomerine teeth 7−17.

Colouration in juvenile preserved specimens of Iluocoetes fimbriatus (UAB.P 44, 113 mm TL; BMNH 1936.8.26.962−972: 77−155 mm TL; BMNH 1912.7.1.84, 140 mm TL; BMNH 1936.8. 26.984−987, 122 mm TL). Head and body mid-brown coloured with dull white spots on both, head (nape, interorbital area, cheeks) and body, mainly in its dorsolateral part. A darker band on head between the anteroventral edge of the eye and the upper jaw. Ventrolateral part of both head and body light brown. Edge of dorsal fin with 5−6 darker bands.

The character state of other diagnostic features of this genus are given in Tables 2−4. Other descriptive characters of I. fimbriatus can be found in Gosztonyi (1977: 211−215). The general shape of Iluocoetes fimbriatus is in Fig. 2 .

Figures

FIGURE 1. Neurocranium of Iluocoetes fimbriatus Jenyns, 1842. (UAB. P 47, 224 mm TL). Lateral view (a) and dorsal view (b). BAS, basioccipital; EPO, epioccipital; ETM CART, ethmoid cartilage; EXO, exoccipital; FR, frontal; INT, intercalary; LAT ETM, lateral ethmoid; MES mesethmoid; PAR, parietal; PAS, parasphenoid; PRO, prootic; PTO, pterotic; PTS, pterosphenoid; SO, supraoccipital; SPH, sphenotic; TGF, trigeminofacialis foramen; V vomer.

FIGURE 2. Iluocoetes fimbriatus BMNH 1936.2.26.988 – 991, 203 mm TL. Left lateral view showing a dark band between the antero-inferior edge of the eye and the upper jaw.

FIGURE 10. Interrelationships among the Magellanic endemic lycodine genera. Consensus tree resulting from the parsimony analysis of 78 morphological characters (Length = 105; CI = 0.53; RI = 0.50). Bootstrap support values (rep = 1000) are indicated on the nodes. White boxes on branches: homoplastic apomorphies; black boxes: synapomorphies.