Chaunax, Lowe, 1846

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 : 149-150

Key to species of Chaunax in Taiwan and adjacent waters

1A. Illicial trough deep, concave and black; illicium very short, housed within illicial trough ( Figs. 2A‒B )............................................................................................. ( C. pictus group) C. penicillatus

1B. Illicial trough shallow, of same color as body; illicium stout to slender ( Figs. 2C‒F )................................ 2

2A. No cirri on dorsal surface of head or above eyes; usually 1 or 3 pairs of spinules flanking lateral-line neuromasts ( Figs. 3A–C ); cirri along body margin flap-like ( Fig. 4A ) or filamentous........................................ 3 ( C. abei group)

2B. Cirri present on dorsal surface of head and above eyes; 3‒8 pairs of spinules flanking lateral-line neuromasts ( Figs. 3D–E ); cirri along body margin filamentous ( Figs. 4B‒C )..............................................6 ( C. fimbriatus group)

3A. Mouth cavity, gill chamber and gill rakers grayish to blackish................................. C. albatrossae sp. nov.

3B. Mouth cavity, gill chamber and gill rakers pale or, rarely, grayish in small areas.................................... 4

4A. Coloration uniformly pink when fresh, without any discrete pattern, sometimes with deep red blotches; esca with pink or whitish cirri; dermal spinules slender and curved....................................................... C. apus

4B. Dorsal surface spotted; esca with brown, green or gray cirri; dermal spinules stout and straight........................ 5

5A. Spinules on dorsal surface all simple; dorsal surface of body densely covered with small spots.............. C. breviradius

5B. Spinules on dorsal surface both bifurcate and simple; large green spots encircled by yellow or large yellow spots on dorsal surface of body.................................................................................. C. abei

6A. Two large white patches on dorsal surface, one associated with underlying third dorsal-fin spine and one before dorsal-fin origin; filaments on body usually highly branched.................................................. C. fimbriatus

6B. No large white patches on dorsal surface; filaments on body surface usually simple................................. 7

7A. Body uniformly red when fresh; esca pink; entire fish turning creamy-white when preserved; BI 29–33; GH 10–11........................................................................................... C. erythraeus sp. nov.

7B. Irregular greenish or orange-red patterns on dorsal surface when fresh; esca green; gray to dark brown blotches and/or reticulates pattern on dorsal surface and esca gray to brown when preserved; BI 32–37; GH 11–13.............................. 8

8A. Very fine greenish-yellow patches on dorsal surface when fresh, these turning brown and forming very fine, pale, reticulated pattern when preserved....................................................................... .. C. umbrinus

8B. Large and irregular green reticulate patterns or yellow patches on dorsal surface when fresh, changing into dark brown reticulate patterns or fading when preserved........................................................................ 9

9A. Mouth cavity pale gray, not especially dark; bright white dots or patches on head and dorsal-fin origin when fresh; irregular green reticulate pattern on dorsal surface when fresh, changing to dark gray blotches with pale reticulate pattern when preserved. C. viridiretis sp. nov.

9B. Mouth cavity dark gray posteriorly; no bright white dots on head or dorsal-fin origin when fresh; dorsal surface with irregular yellow patches when fresh, but patches fading after preservation, forming pale blotches with light brown reticulate patterns...................................................................................... C. obscurus sp. nov.

Figures

FIGURE 2. Dorsal views of heads showing illicium and illicial trough of Chaunax species.A. C. penicillatus, NMMB-P23379. B. C. pictus, MNHN 1981-1273, illicium held erect by forceps. C. C. abei, NMMB-P26756. D. C. apus, ASIZP 63182. E. C. fimbriatus, ASIZP 63257. F. C. obscurus sp. nov., NMMB-P71252. All specimens fresh except C preserved.

FIGURE 3. Scanning electron micrographs (SEM) showing neuromasts and their neighbor spines along the sensory canals.A‒ C. C. abei species group: C. apus, ASIZP 64564, 154 mm SL (A), C. gomoni, NSMT-P95092, 170 mm SL (B), and C. russatus, BSKU 44629, 221 mm SL (C). D‒E. C. fimbriatus species group: C. fimbriatus, ASIZP 70143, 148 mm SL (D), C. umbrinus, and ASIZP 70334, 186 mm SL (E). F. C. pictus species group: C. penicillatus, ASIZP 58059, 126 mm SL.

FIGURE 4. Two forms of cirri on body surface of Chaunax species.A. Flap-like cirri in C. apus,ASIZP 63182.B‒C. Filamentous cirri in C. fimbriatus, NMMB-P34718, 211 mm SL, and C. obscurus sp. nov., ASIZP 71252, 175 mm SL, respectively.