Gymnapogon janus, Fraser, Thomas H., 2016

Fraser, Thomas H., 2016, A new species of cardinalfish (Gymnapogon, Gymnapogonini, Apogonidae, Percomorpha) from the Philippines, Zootaxa 4107 (3), pp. 431-438 : 433-436

Gymnapogon janus new species

Figures 1–3

Diagnosis. A species of Gymnapogon with 9 or 10 soft anal rays, anterior-most unbranched; 10 soft dorsal rays, two anterior-most unbranched; pectoral fins 14, with 9 branched and 5 unbranched rays; caudal fin rounded, 17 principal caudal rays with 15 branched; one row of two villiform teeth on each side of vomer.

Description

Holotype: dorsal fin VI‒I,10, anterior two soft rays simple, remainder branched, last soft ray split to its base; anal fin II,9, anterior soft ray simple, remainder branched, last soft ray split to its base; pectoral fins 14‒14, lower 3 unbranched and upper 2 unbranched; pelvic fins I,5 with inner ray attached to body for most of its length; principal caudal fin-rays 15 (8+7) branched, 2 unbranched; dorsal procurrent-rays 10, ventral procurrent-rays 9; caudal fin rounded; gill rakers and rudiments 1‒1+9‒2, total elements 13, well developed rakers 11, upper arch elements 2, lower arch elements 11.

Vertebrae 10+14 ( Fig. 2 A); first four vertebral supraneurals and pterygiophores 0/0/0‒1/2/1; haemal pterygiophores 3/1; one supernumerary dorsal spine; one supernumerary anal spine; PU2 with a crest; 2 epurals; terminal centrum fused to hypurals 3+4, no urostylar sheath; parhypural fused to hypurals 1+2, sutured with terminal centrum; hypural 5 free and splint-like.

Infraorbitals, opercle and posttemporal smooth; preopercle ridge smooth, edges smooth except for single large spine near angle.

Premaxilla teeth with a gap at symphysis, then recurved in 2‒3 rows followed by 2‒3 rows of smaller teeth, one or 2 teeth exposed when mouth is closed; dentary teeth with a gap at symphysis, then 3‒4 rows of recurved villiform teeth tapering to 2 rows on side with a few slightly larger teeth on side; palatine with a single row of small teeth; vomer with 2 villiform teeth on each side; no teeth on basihyal or ectopterygoid.

Free neuromasts ( Fig. 3 ): Head covered with lines of free neuromasts, not all visible; no neuromasts visible on body or caudal fin.

Preserved color ( Fig. 1 A): four small melanophore dots behind eye, two dots on upper opercle, a line of melanophore dots from near tip of opercle along mid-line ending about a vertical line with origin of second dorsal fin, scatter of small melanophore dots at base of caudal fin and on to base of fin rays, several midline dots anterior to base.

Paratype: dorsal fin VI‒I,10, anterior two soft rays simple, remainder branched, last soft ray split to its base; anal fin II,10, anterior soft ray simple, remainder branched, last soft ray split to its base; pectoral fins 14‒14; pelvic fins I,5 with inner ray attached to body for most of its length; principal caudal fin-rays 15 (8+7) branched, 2 unbranched; dorsal procurrent-rays 10, ventral procurrent-rays 9; caudal fin rounded; gill rakers and rudiments 1‒2+10‒1, total elements 14, well developed rakers 12, upper arch elements 3, lower arch elements 11.

Vertebrae 10+14 ( Fig. 2 B); first four vertebral supraneurals and pterygiophores 0/0/0‒1/2/1; haemal pterygiophores 3/1; one supernumerary dorsal spine; one supernumerary anal spine; PU2 with a crest; 2 epurals; terminal centrum fused to hypurals 3+4, no urostylar sheath; parhypural fused to hypurals 1+2, sutured with terminal centrum; hypural 5 free and splint-like.

Infraorbitals, opercle and posttemporal smooth; preopercle ridge smooth, edges smooth except for single large spine near angle.

Premaxilla teeth with a gap at symphysis, then recurved in 2‒3 rows followed by 2‒3 rows of smaller teeth, one to three teeth exposed when mouth is closed; dentary teeth with a gap at symphysis, then 3‒4 rows of recurved villiform teeth tapering to 2 rows on side with a few slightly larger teeth on side; palatine with a single row of small teeth; vomer with 2 villiform teeth on each side; no teeth on basihyal or ectopterygoid.

Free neuromasts: Head with a few partial lines of free neuromasts, most not visible; no neuromasts visible on body or caudal fin.

Preserved color ( Fig. 1 B): a few dots on head; a linear series of faint dots from near tip of opercle along midline ending about a vertical line with origin of second dorsal fin, no other patterns present.

Etymology. Janus , a Roman God of gates and doors represented by two faces. Here referring to the rounded caudal fin when scales have been sloughed off for some specimens of Pseudamia but with internal characters and preopercle spine of Gymnapogon .

Material examined. Gymnapogon janus n. sp. Holotype. USNM 314651, 62.5 mm SL, Visayan Sea between northern Negros & Masbate Islands, southeast of Sicogon I., 11.3667̊°N; 123.33̊°W, Philippines, Sting Ray V, Sta.T- 29, Sp-78, L. Alcala, G. Hendler, L.W. Knapp, 9 Jun 1978, 24 m otter trawl, depth 0 to 38.4 m, digital x-ray. Paratype. USNM 150854, 55.9 mm SL, San Januico Strait, North of Nababuy Island (Reef); Off East Coast of Leyte Island, Philippines, Albatross Philippine Expedition, 1907–1910, 13 Apr 1908, Dynamite, 1 to 3 m, digital x-ray.

Comparative material. Acanthapogon vanderbilti , Holotype ANSP 68381, 18.8 mm SL, Kiritimati (Christmas I.), Kiribati, 6 May 1937, digital from film x-ray. Paratypes ANSP 68382-96 (15, 11.1–17.0 mm SL), same data as holotype. Australaphia annona Holotype, AMS IA 6469, 35.8 mm SL, Whitsunday Passage, Lindeman I., Queensland, Australia, Apr 1935, digital x-ray. Gymnapogon africanus Holotype SAIAB 358, 38.2 mm SL, Shimoni, Kenya, 21 Nov 1952, digital from film x-ray. Paratypes: SAIAB 776 (5, 14.3–34.8), Ibo Mozambique, digital from film x-ray. SAIAB 777 (1, 31.7), Bazaruto, Mozambique, Oct 1953, digital from film xray. SAIAB 778 (4, 23.0–31.9), Shimoni, Kenya, 1952, 18 Aug 1951, digital from film x-ray. Gymnapogon japonicus Syntypes, BMNH 1905.6.6.113-22, (39, 26.5–35.5), Inland Sea of Japan, R. Gordon Smith, digital xrays. Syntype USNM 108821 (1, 29.9), Inland Sea of Japan, R. Gordon Smith, digital of film x-ray. UMMZ 183258 (6, 32.2–43.1), vicinity of Nagasaki, Kyushu, Japan, 16 July 1929. Gymnapogon sp. UMMZ 183257 (2, 29.9–30.1), Obama Bay, Fukui-ken, Japan, 4 Aug 1929, digital x-ray. Gymnapogon urospilotus Holotype USNM 142404, 26.8 mm SL, Lagoon reef near Ennylabecan I., Kwajekein Atoll, Marshall Is., 1 Sep 1946. Henicichthys philippinus , Holotype CAS-SU 34379, 32.0 mm SL, Nasugbu, Luzon I., Philippines, 11 Dec 1936, digital from film x-ray. Paratypes CAS-SU 34380 (3, 26.5–27.5), Nasugbu, Luzon I., Philippines. CAS-SU 34381 (4, 19.0–27.9), Dumaguete, Oriental Negros, Philippines, 26 Dec 1936.

Remarks. Other nominal species of Gymnapogon with 9 to 11 soft dorsal-fin rays and 9 or 10 soft anal-rays include G. annona ( Whitley 1936) , G. foraminosus , G. japonicus Regan 1905 . G. urospilotus and G. vanderbilti . The B-shaped dark mark on the base of the caudal fin, 13 principal branched caudal rays, 2 upper and 2 lower unbranched principal caudal rays, forked caudal fin and the small upper preopercle spine separates Gymnapogon urospilotus and G. vanderbilti complex of species or populations (initial molecular data Mabuchi et al 2014; Leis et al 2015) from G. janus n. sp. Based on radiographs and additional study of Fowler’s holotype and paratypes of Gymnapogon vanderbilti , I find the soft anal rays are 10 like G. urospilotus . Whitley’s figure 6 of the holotype Australaphia annona , shows a bifurcated opercle spine, a single unbranched soft dorsal-fin ray, forked caudal fin and his description included 13 branched principal caudal-fin rays. Gymnapogon melanogaster shares the bifid preopercle spine and forked caudal fin with 13 branched principal caudal-fin rays, but differs by having all soft dorsal and anal rays branched. Smith (1954) described Gymnapogon africanus with 13 branched principal caudal rays, forked caudal fin, a simple opercle spine, a single unbranched soft dorsal-fin ray remaining branched and 8 branched soft anal rays.

Gymnapogon japonicus shares more characters with G. j a n u s n. sp. than any other nominal species. Regan first described the Japanese species from ‘numerous specimens’ (at least 39 specimens). Later in two papers (1940a & b) he added information having examined an alizarin (cleared with KOH and stained) and dissected another specimen. Regan reported 10+15 vertebrae. Smith (1954) and Fraser (1972) reported 10+14 vertebrae. An examination of radiographs for 39 syntypes all showed 10+14 vertebrae. Regan (1905) described the caudal fin as being “Caudal subtruncate or rounded, the posterior edge usually slightly emarginate.” Regan (1940a) recorded the principal caudal-fin rays as 17 with 15 branched and about 10 procurrent rays above and below in advance of the principal rays. Counts from the radiographs of the types were 13 (7+6) branched for four specimens, 14 (7+7 or 8+6) branched for two specimens and 15 (8+7) branched for one specimen. Principal caudal ray counts of other specimens were unavailable because of damage. The procurrent rays of the type series were 9 upper, 9 lower for 4 specimens, 10+9 for eight specimens, 11+ 9 for one specimen, 11+10 for one specimen, 11+11 for one specimen. Pectoral fin-ray counts were 12–14 with two upper and lower unbranched. Some of Regan’s specimens have a wide blackish band along the caudal region, others may have a central darkish area with a suggestion of a faint outside ring.

Regan (1940a & b) placed Gymnapogon foraminosus as a synonym of G. japonicus based on the text and figure by Tomiyama (1936). Lachner (1953) agreed with Regan’s action. Tomiyama’s figure is a 45 mm SL specimen in formalin shows all branched soft dorsal rays, a single unbranched anal ray, an emarginate caudal fin and in the text 13 pectoral rays. He studied under Shigeho Tanaka and examined four specimens of Gymnapogon foraminosus that likely included Tanaka’s type from Nagasaki (a listed specimen locality). Tomiyama described dentition as row 2 or 3 enlarged vomerine teeth and some anterior canines on the premaxilla. Neither Tanaka nor Tomiyama reported a preopercular spine in their material. They may have overlooked a very short spine like that of the UMMZ specimens described in the paragraph below. If so, the status of Gymnapogon foraminosus needs further investigation.

Hayashi (1984) described Gymnapogon japonicus as having 12 pectoral rays. Specimens examined from Nagasaki, Japan (UMMZ 183258) have 12 pectoral rays with 8 branched rays, two upper and two lower unbranched rays, first anal ray branched, first dorsal ray unbranched, a short, simple preopercular spine, rounded caudal fin and 13–15 branched principal caudal rays. Four specimens have 6+6 procurrent rays with and two specimens have 9+8. The partially dried specimens of UMMZ 183257 have first anal ray branched, first dorsal ray unbranched, 14 pectoral rays with upper and lower two rays unbranched, procurrent ray counts (8+8 and 9+8), 13 branched caudal rays, emarginate caudal fins and single, simple preopercle spines. Data from these two collections suggest species of Gymnapogon in Japan are not well understood, with G. foraminosus perhaps valid.

The paintings online and in print for four species of Gymnapogon by I.L. Jeng appear stylistic ( Shao 2015; Shen 1993). The artist shows all branched soft rays in the dorsal and anal fins for Gymnapogon japonicus , G. philippinus , G. urospilotus and G. annona , only a single large preopercle spine without bifurcation for G. annona or the small upper spine for urospilotus and none with a rounded caudal fin.

The range of variation for various fin-ray counts, branched fins, and shape of the caudal fin noted in the above paragraphs suggest that there may be two or more species in Japanese waters.

Dentition of G. janus n. sp. is unlike G. japonicus or G. foraminosus with the vomer having 2 small teeth on each side and the premaxilla teeth slightly enlarged. The distribution of small melanophores on the head and body provide little support for any conclusions about possible species specific color patterns.

Figures

FIGURE 1. Lateral view of the left side of Gymnapogon janus n. sp. by T. Fraser. A. Holotype USNM 314651, 62.5 mm SL, fixed in formalin, preserved in 70 % ethyl alcohol B., Paratype USNM 150854, 55.9 mm SL, fixed in ethyl alcohol, preserved in 70 % ethyl alcohol. Caudal fin apparently damaged post radiograph.

FIGURE 2. Gymnapogon janus n. sp., positive radiographs from negatives taken by Sandra Raredon. A. Holotype USNM 314651 mm SL, B., Paratype USNM 150854, 55.9 mm SL.

FIGURE 3. Gymnapogon janus n. sp., holotype USNM 314651, 62.5 mm SL, Incomplete pattern of free neuromasts and canal pores of the head. A. Dorsal view. B Right lateral view reversed. C. Ventral view of right dentary. AI = anterior supraorbital pore, AN = anterior nare, M = mandibular pore, P = preopercle spine, PN = posterior nare. Scale = 3 mm.