Chaunax viridiretis, Ho & Ma, 2022

Ho, Hsuan-Ching & Ma, Wen-Chun, 2022, Four new species of the frogmouth genus Chaunax (Lophiiformes: Chaunacidae) from Taiwan and the Philippines, Zootaxa 5189 (1), pp. 146-179 : 170-171

Chaunax viridiretis sp. nov.

Green-net frogmouth

Figs. 14D , 16, 17; Tables 1‒3 , 5

urn:lsid:zoobank.org:act:85DEDE30-A621-4AED-86D8-C99844D9C38D

Holotype. ASIZP 64503 (196), ca. 24°58’N, 121°58’E, off Da-xi , Yilan, northeastern Taiwan, northwestern Pacific Ocean, ca. 300 m, 19 Jun. 2004, coll. H.-C. Ho, purchased from Da-xi fish market.

Paratypes. Nine specimens, 162‒203 mm SL. ASIZP 64499 (2, 165–192), AMS I.44816-001 (ex. ASIZP 64499 , 162 ) , USNM 395937 (ex. ASIZP 64499 , 2 , 168–203 ), 13 Jun. 2004 ; ASIZP 64567 (3, 165–183), AMS I.44816-002 (ex. ASIZP 64567 , 177 ), 7 Jul. 2004 ; ASIZP 64569 (2, 148–172), 7 Jul. 2004 ; ASIZP 65400 (1, 168), 7 Jul. 2004 ; NMMB-P23373 (1, 159), 7 Jul. 2004 ; NMMB-P23374 (1, 180), 7 Jul. 2004 ; all collected from near type locality.

Etymology. The specific name is a genitive noun phrase formed by combining the Latin adjective viridis, meaning green, and the genitive form retis of the Latin noun rete, meaning net, refers to the greenish irregular reticulate pattern on the body surface.

Diagnosis. Species in C. fimbriatus group displaying irregular green reticulate pattern on dorsal surface when fresh, with patches of small, bright white spots on interorbital space, head and origin of dorsal fin. Mouth cavity pale and gill chamber blackish. llicium short and stout; esca yellowish green. Slender cirri arising within interorbital space and on lower part of maxilla and supraocular membranes. Spinules on dorsal surface relatively strong and stout, their interspaces being shorter than their lengths. BD 2–3, GH 11–13, BI 32–35; GRii 8–9; P 13–14 (mainly 14).

Description. Morphometric (expressed as % SL) and meristic data are provided in Tables 1‒3 , 5 . Following data provided first for holotype, followed in parentheses by range for paratypes, when different.

D III, 12; P 13–14 (mainly 14); A 7; C 9. Lateral-line neuromasts: AB 11 (11–12); AC 8 (7–8); BB 6; BB’ 4 (4–5); BD 2 (2–3); CD 6 (6–7); DG 4 (3–5); EF 6 (5–7); FG 3; GH 12 (11–13); BI 33/35 (32–37), including 2–4 on caudal-fin base. Gill rakers: GRi 3–5+8–10=11–14; GRii 8–9; GRiii 1+9 =10 (1+8–9=9–10); GRiv 7.

Head length 2.5 (2.3–2.7) in SL; head width 5.4 (5.1–5.7) in SL, 2.2 (2.1–2.3) in HL; pre-preopercular length 3.5 (3.3–3.9) in SL, 1.4 (1.3–1.6) in HL; predorsal length 2.1 (1.9–2.1) in SL; pre-gill opening length 1.6 (1.5–1.7) in SL; illicial length 10.4 (8.3–13.2) in HL; illicial trough length 6.1 (5.2–6.8) in HL; pre-illicium length 13.5 (11.0–15.3) in HL; eye diameter 5.5 (4.9–6.6) in HL; upper jaw 4.7 (4.3–5.0) in SL, 1.9 (1.8–2.0) in HL; post-anus length (tail 1) 3.4 (3.2–3.7) in SL, 1.4 (1.3–1.5) in HL; post-dorsal length (tail 2) 5.9 (5.3–6.9) in SL, 2.4 (2.2–2.7) in HL; post-anal length 7.2 (6.3–8.2) in SL, 2.9 (2.5–3.3) in HL; caudal peduncle depth 4.3 (3.9–4.7) in HL; caudal fin length 3.4 (3.2–3.6) in SL, 1.4 (1.3–1.5) in HL.

Body rather robust. Interorbital space broad and skull slightly elevated posteriorly. Skin relatively thick, tips of pectoral- and pelvic-fin rays well-connected to each other by skin. Caudal peduncle somewhat cylindrical, short and stout, tapering posteriorly.

Illicium short and stout, esca with broad central tongue bearing many thin, greenish or yellowish cirri. Illicial trough relatively deep, oval, about 1.7 times longer than wide and shorter than eye window diameter.

Dermal spinules relatively short and stout ( Figs. 12F‒G ), forming rough skin covering entire body except for eye windows, outer half of pectoral fins, entire anal fin and membranes of all fins; interspaces between dermal spinules slightly longer than spinule lengths. Wide transverse band of 7 or 8 rows of dermal spinules in front of illicial trough. Interspaces of lateral-line neuromasts slightly greater than the width of neuromasts; 3 or 4 pairs of short spinules flanking neuromasts.

Teeth relatively slender and fang-like. Band of 5–6 irregular rows of teeth on upper jaw, those on middle and in inner row slightly longer than others, posterior one-third of band narrowing; band of 3–4 irregular rows of teeth on lower jaw, these teeth slightly longer than those of upper jaw, with those in innermost row slightly longer than others. Vomer with two bands of teeth separated by small gap, with 3 irregular tooth-rows in each band. Each palatine with single band of small teeth.

Cirri on external surfaces of both jaws, interorbital space, supraocular membrane, dorsal surfaces of head and body, lower part of premaxilla, lateral sides of body and caudal peduncle; those on interorbital space and dorsal surface of head sometimes branched.

Coloration. When fresh, body reddish with irregular greenish reticulate pattern on dorsal surface and paler ventral surface; small bright-white spots in small patches on interorbital space, head and origin of dorsal fin; esca yellowish-green. When preserved, dorsal surface showing gray reticulate pattern, esca brownish. Mouth cavity pale anteriorly, grayish posteriorly; gill chamber and peritoneum black.

Distribution. Currently only known from the type series collected (according to the fishermen involved) by bottom trawl from a rocky bottom near the coast of northeastern Taiwan at depths of about 300 m. Likely an endemic species in this area, in light of the first author’s more than 20 years of observations in many museum collections.

Remarks. Chaunax viridiretis sp. nov. shares similar body proportions and meristic values with C. fimbriatus and C. obscurus , which co-occur with it in northeastern Taiwan ( Tables 1–3 , 5 ). When fresh, C. obscurus has yellow patches on an orange-red background, which fade after preservation to form pale patches with light brown reticulations, whereas C. viridiretis has small, yellow-green patches on a reddish background, which turn dark gray after preservation and form a dark-brown marbled pattern with paler reticulations ( Fig. 14A , vs. 14D). Furthermore, the mouth cavity of C. obscurus is gray anteriorly and black posteriorly ( Fig. 13D ), while that of C. viridiretis is mostly pale, with the pharyngeal region light gray. Chaunax viridiretis sp. nov. differs from C. fimbriatus in having fine greenish reticulation on dorsal surface and bright white patches on the interorbital space, head and origin of the dorsal fin (vs. a yellowish or reddish pattern with two bright-white patches on the dorsal surface); greenish cirri on the esca when fresh (vs. grayish to brownish cirri); relatively stout (vs. slender) spinules; BD mainly 2 (vs. 3); and CD mainly 6 (vs. 7).

Among non-sympatric species, C. viridiretis sp. nov. is similar to C. umbrinus in having a complicated reticulate color pattern, but can be distinguished by the pattern’s greenish color and the bright white patches on the interorbital space, head and origin of the dorsal fin (vs. a fine yellowish or reddish pattern and no white patches); greenish cirri on the esca (vs. brownish cirri); relatively stout (vs. relatively slender) spinules; and DG modally 4 (vs. modally 3), CD modally 6 (vs. modally 7) ( Tables 1‒4 ).

Figures

FIGURE 12. Dermal spinules of three other species in Chaunax fimbriatus species group, SEM. A‒C. C. obscurus sp. nov., NMMB-P34693, 170 mm SL: A, spinules beside neuromast; B‒C, skin above eye. D‒E. C. umbrinus, ASIZP 70334, 248 mm SL, skin above eye. F‒G. C. viridiretis sp. nov., ASIZP 64499, paratype, 165 mm SL, skin above eye.

FIGURE 13. Details of two species in Chaunax fimbriatus species group. A‒E. C. obscurus sp. nov. (A‒C, E, holotype; D, paratype, ASIZP 71252):A, dorsal view of head; B, dorsal view of dorsum; C, ventral view of left side of head; D, mouth cavity; E, dark coloration within right gill chamber. F. C. fimbriatus, NMMB-P34718, 211 mm SL, pale coloration within right gill chamber.

FIGRUE 14. Preserved coloration on dorsal surface of four species in Chaunax fimbriatus species group. A. C. fimbriatus, NMMB-P13862, 115.7 mm SL. B. C. obscurus sp. nov., ASIZP 71252, 175 mm SL. C. C. umbrinus, NMMB-P23460, 216 mm SL. D. C. viridiretis sp. nov., ASIZP 64503, 196 mm SL. Not to scale.