Chaunax erythraeus Ho & Ma 2022, sp. nov.
Creators: name: Ho, Hsuan-Ching
name: Ma, Wen-Chun
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Actinopterygii
Lophiiformes
Chaunacidae
Chaunax
Chaunax erythraeus

description: Chaunax erythraeus sp. nov.
Red eyebrow frogmouth
Figs. 8, 9, 10A‒D; Tables 1‒3, 5
urn:lsid:zoobank.org:act: 5C36C1B7-4329-4943-B4E0-8911C24A5D06
Holotype. NMMB-P21097 (1, 225), ca. 24°30’N, 125°25.2’E, off Da-xi, Yilan, northeastern Taiwan, northwestern Pacific Ocean, bottom trawl, ca. 300 m, 17 Jun. 2013, purchased from fish market.
Paratypes. NMMB-P21098 (1, 203), 17 Jun. 2013; ASIZP 63219 (1, 224), 24 Apr. 2004; both collected from near the type locality.
Etymology. The specific name erythraeus, a Latin adjective meaning reddish, refers to the uniformly pinkishred coloration, which is unique among the members of the C. fimbriatus species group.
Diagnosis. Body uniformly pinkish- or orange-red when fresh, mouth cavity light gray but darker in pharyngeal region, gill chamber entirely black. Tail short and stout (TL1=27.1‒27.9% SL; TL2=13.5‒16.1% SL; TL3=10.4‒ 11.1% SL). GH 10 (rarely 11), BI 29‒33, GRii 8‒9, P 13.
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; A 7; C 9. Lateral-line neuromasts: AB 10/10 (10‒11); AC 8/8 (8); BB 6 (6); BB’ 4 (4); BD 3/3 (2‒3); CD 7/6 (6‒7); DG 4/4 (3‒4); EF 6/6 (6); FG 3/3 (3); GH 10/11 (10‒11); BI 32/33 (29‒33), including 3/4 (3‒4) on caudal fin base. Gill rakers: GRi 3+9= 12 (3+8‒9=11‒12); GRii 9 (8‒9); GRiii 1+9=10 (1+7‒9=8‒10); GRiv 7 (6‒7)
Head length 2.4 (2.4‒2.5) in SL; head width 5.2 (4.5‒5.5) in SL, 2.2 (1.9‒2.2) in HL; pre-preopercular length 3.5 (3.5) in SL, 1.4 (1.4) in HL; predorsal length 2.1 (2.0‒2.1) in SL; pre-gill-opening length 1.7 (1.6‒1.7) in SL; illicial length 13.6 (10.3‒13.6) in HL, illicial trough length 6.7 (5.9‒6.8) in HL; eye diameter 5.6 (5.0‒5.6) in HL; upper jaw 4.7 (4.7‒4.8) in SL, 1.9 (1.9‒2.0) in HL; post-dorsal fin length 6.3 (6.2‒7.4) in SL, 2.6 (2.5‒3.0) in HL; post-anus length 3.6 (3.6‒3.7) in SL, 1.5 (1.4‒1.5) in HL; post-anal fin length 9.7 (9.0‒9.3) in SL, 4.0 (3.7‒4.0) in HL; caudal peduncle depth 4.4 (4.1‒4.4) in HL; caudal fin length 3.5 (3.5‒3.7) in SL, 1.5 (1.4‒1.5) in HL.
Body robust, relatively deep and broad. Head globular with broad interorbital space; skull slightly elevated posteriorly. Trunk cylindrical. Skin relatively thin, loose and flaccid; tips of pectoral- and pelvic-fin rays well connected by membranes. Caudal peduncle relatively short and stout, slightly cylindrical, tapering posteriorly.
Illicium short and stout; esca with fat central tongue bearing many thin, pink cirri. Illicial trough relatively shallow, oval, about 1.5 times longer than wide, slightly smaller than eye window. Second dorsal-fin spine close to illicium, third dorsal-fin spine situated at about midpoint of pre-dorsal distance, both spines embedded beneath skin.
Dermal spinules relatively thin and slender (Figs. 10A‒D), mostly simple but those on body mixed with very sparse bifurcate spinules; interspaces of dermal spinules about equal to their length. In front of illicial trough, wide band of 4 rows of dermal spinules and more posterior narrow band of 1‒2 rows separated by short naked area; 3‒4 pairs of short spinules bridging successive neuromasts. Interspaces of lateral-line neuromasts much wider than width of neuromast.
Teeth relatively slender, fang-like. Broad band of about 8 irregular rows of teeth on upper jaw, those situated mesially slightly larger, posterior one-third of band tapering. Band of about 6 irregular rows of teeth on lower jaw; teeth similar in size to those in upper jaw, those of innermost row slight longer than others. Vomer with 2 bands of teeth separated by small gap, each band comprising about 4 irregular tooth rows. Each palatine with single band of about 4 rows of small teeth.
Cirri present on external surface of both jaws, membrane above eye, interorbital space, dorsal surfaces of head and body, lower part of premaxilla, lateral sides of body and caudal peduncle; those on dorsal surface of head sometimes branched.
Coloration. When fresh (Figs. 8. 9A), body surface uniformly pinkish-red with ventral side paler; cirri on esca pinkish with orange tips; cirri on body white to pink; gill chamber uniformly black (Fig. 9D); mouth cavity white anteriorly, gradually becoming gray posteriorly. After preservation, body surface uniformly creamy-white; illicium, esca and illicial trough pale; gill chamber uniformly black; gill arches light gray; and peritoneum black.
Distribution. Only known from three species in the type series collected from northeastern Taiwan at depths of around 300 m; apparently endemic to this region.
Remarks. Chauanx erythraeus sp. nov. is the only species among the ten species recognized in the C. fimbriatus species group with a uniformly pinkish- or orange-red coloration (uniformly creamy-white when preserved) and a uniformly black gill chamber (vs. a uniformly pale gill chamber or one with some black patches; Ho, pers. obs.).
Chaunax flammeus, known only from the holotype taken off northern Madagascar, also has a uniformly pale body color when preserved, but Le Danois (1979) stated that the fresh adult is yellow-pink with irregular marbling. In addition, C. erythraeus has a relatively short tail (TL1=27.1‒27.9% SL, TL2=13.5‒16.1% SL, TL3=10.4‒11.1% SL) compared to that of C. flammeus (TL1=34.1% SL, TL2=18.5% SL, TL3=16.9% SL); and a black gill chamber (vs. uniformly pale).
Chaunax hollemani Ho & Ma 2016 also displays a uniformly creamy-white color when preserved, but its fresh coloration is still unknown. It differs from C. erythraeus in having different numbers of lateral-line neuromasts: DG 3 (vs. mainly 4), GH 11‒14 (mainly 11; vs. 10‒11, mainly 10), and BI 33‒38 (vs. 29‒33). It also has a relatively longer tail (TL1=28.9‒31.8% SL, TL2 15.2‒19.4% SL, TL3=13.7‒15.9% SL), compared to those of C. erythraeus (TL1= 27.1‒27.9%SL, TL2=13.5‒16.1% SL and TL3= 10.4‒10.7% SL).
The remaining 8 congeners in the C. fimbriatus species group have complex color patterns that easily allow their separation from C. erythraeus.
description: Published as part of Ho, Hsuan-Ching & Ma, Wen-Chun, 2022, Four new species of the frogmouth genus Chaunax (Lophiiformes: Chaunacidae) from Taiwan and the Philippines, pp. 146-179 in Zootaxa 5189 (1) on pages 158-163, DOI: 10.11646/zootaxa.5189.1.17, http://zenodo.org/record/7119369