Lophiomus Gill, 1883

Chen, Hsuan-Pu, Lee, Mao-Ying & Chen, Wei-Jen, 2024, Integrative taxonomy reveals unanticipated hidden diversity in the monotypic goosefish genus Lophiomus (Teleostei, Lophiidae), with description of three new species and resurrection of Chirolophius laticeps Ogilby, 1910, European Journal of Taxonomy 943, pp. 239-287 : 256-258

Genus Lophiomus Gill, 1883

Lophiomus Gill, 1883 [1882]: 552. Type species: Lophius setigerus Vahl, 1797 . Original designation.

Diagnosis

Lophiomus can be separated from other extant lophiid genera by the combination of vertebrae 18– 19; dorsal-fin rays 8; anal-fin rays 6; flat body shape; presence of third dorsal-fin spine, humeral, and subopercular spines; rugose frontal ridge; gill opening not extending anterior to the pectoral-fin base; single articular spine; single quadrate spine; two sphenotic spines; two interopercular spines; the outer surface of maxilla bearing low and conical knobs; ural centrum bearing transverse processes; and the floor of mouth with distinct dark pigmentations (except Lm. immaculioralis ).

Differential diagnosis

Lophiomus can be readily distinguished from Sladenia by its flat body shape (body shape rounded in Sladenia ). Among the flat-bodied lophiid genera, Lophiomus can be differentiated from Lophiodes by its rugose frontal ridge (frontal ridge smooth in Lophiodes ), gill opening not extending anteriorly to the pectoral-fin base (gill opening extending anterior to the pectoral-fin base in Lophiodes ), a single articular spine (two articular spines in Lophiodes ), two sphenotic spines (one inner sphenotic spine in Lophiodes ), and one ural centrum bearing transverse processes (ural centrum without transverse processes in Lophiodes ) ( Fig. 7 , Supp. file 5). Lophiomus can also be distinguished from its sibling genus Lophius in having vertebrae 18–19 (vertebrae more than 20 in Lophius ), dorsal-fin rays 8 (9–12 in Lophius ; Caruso 1985), anal-fin rays 6 (8–10 in Lophius ; Caruso 1985), interopercular with two spines (single spine in Lophius ), the outer surface of maxilla bearing low and conical knobs (smooth outer surface in Lophius ), and quadrate with a single spine (two spines in Lophius ) ( Fig. 7 , Supp. file 5).

General description

MEASUREMENTS AND MERISTIC COUNTS. Dorsal-fin spines 5–6; dorsal-fin rays 8; anal-fin rays 6; pectoral-fin rays 21–26; pelvic-fin rays 6–7; branchiostegal rays 5; interopercular spines 2; vertebrae 18–19; outermost row of premaxillary teeth 6–35. SL 69.3–292.5 mm; HL 27.3–39.9%, TL 41.0–59.6%, IL 16.5–33.7%, DS2 15.0–25.7%, DS3 16.3–33.7%, DS4 8.4–26.0% of SL; HW 37.4–68.6%, HD 69.3– 88.6%, SNL 54.2–82.9%, SNW 28.5–56.5%, ISP 33.0–56.7%, IF 30.9–55.8%, PTSP 10.7–19.6%, QPAL 47.3–82.9%, OPSOP 31.6–65.7% of HL (adults).

HEAD AND BODY. Body shape strongly depressed; gill opening not reaching beyond base of pectoral-fin base; pectoral-fin broad; frontal ridge and outer surface of maxilla (and dentary in some species) rugose, bearing low conical knobs; parietal spines strong and sharp; quadrate with single lower spine; inner and outer sphenotic spines well developed; epiotic spines well developed; articular spine one, anterolateral to jaw joint; subopercular spine one; interopercular spines two; humeral spine well developed and complex, with three to five spinelets; ural centrum depressed, with transverse process; eye suboval; esca pennant-like or tassel-like flap; preserved coloration pale khaki to brown dorsally; light ventrally; peritoneum pigmentation from light to dark; floor of mouth with dark pigmentations except Lm. immaculioralis sp. nov., ranging from light background with reticulate dark pattern, anastomosing dark pattern, to dark background with circular or irregular pale pattern; lateral surface of lower jaw, head, and caudal peduncle with well-developed tendrils.

Remarks

This genus was thought to be monotypic since Caruso (1983). The present study re-defines it by including the result of CT-scan and the descriptions of four additional species. Unlike the characteristics described by Caruso (1983, 1985) for this genus, which include a floor of the mouth with a distinct dark marking and 6 dorsal-fin spines, the newly described species, Lm. immaculioralis sp. nov., features a floor of the mouth without a distinct dark marking and 5 dorsal-fin spines. Consequently, the generic definition of this genus is herein revised accordingly.

It is noteworthy that meristic counts of dorsal-fin rays and anal-fin rays were often misinterpreted in studies conducted before Caruso (1983) when X-ray or CT scanning was not available for the examinations ( Table 1 ). The dorsal-fin rays are found to be forked in the last ray at least in Lm. laticeps ( Fig. 10E ), which may have led previous researchers to miscount the dorsal-fin rays as nine. The anal-fin rays were also miscounted as seven in previous descriptions ( Table 1 ).

Figures

Fig. 7. Cranial comparative osteology of the three lophiid genera. A. Lophiodes mutilus (Alcock, 1894). B. Lophius litulon (Jordan, 1902). C. Lophiomus setigerus (Vahl, 1797). Scale bars = 10 mm.

Fig. 10. Chirolophius laticeps Ogilby, 1910, holotype (AMS E. 2973). A. Preserved specimen, dorsal view. B. Ventral view. C. Floor of mouth. D. X-ray radiograph in dorsal view. E. X-ray radiograph in lateral view (white triangles indicate the dorsal-fin spines; gray triangles indicate the dorsal-fin rays). Photographed by K. Parkinson.