Phyllophichthus diandrus, Hibino & Endo & Ho, 2024

Hibino, Yusuke, Endo, Shunsuke & Ho, Hsuan-Ching, 2024, A new species of Phyllophichthus Gosline, 1951 (Actinopterygii, Ophichthidae) from Taiwan, ZooKeys 1220, pp. 35-44 : 35-44

Phyllophichthus diandrus sp. nov.

Figs 1 , 2 A , 3 , 4

Phyllophichthus sp.: Hibino 2019: 149 (Dong-gang, Taiwan).

Type material.

Holotype: NMMB-P 28224 , 270 mm TL, ca 22°26'N, 120°24'E, Dong-gang , Pingtung, southwestern Taiwan, northern South China Sea, mid-water trawl, 6 Jan. 2017, collected by H.-C. Ho.

Diagnosis.

Inside of anterior-nostril tube with two papillae; dorsal-fin origin well behind tip of pectoral fin, distance from the tip to the origin of dorsal fin 0.6 times of the fin; no teeth on maxilla and vomer; 25 branchial aches; vertebral formula 12-69 - 160.

Description.

Measurements in mm (% of TL in parenthesis): HL 22.4 (8.3 %); preanal length 128.1 (47.5 %); tail length 141.7 (52.5 %); predorsal length 29.8 (11.0 %); body depth at gill opening 4.7 (1.7 %); body depth at mid anus 6.2 (2.3 %). Measurements in mm (% of HL) in parenthesis: snout length 5.2 (23.2 %); eye diameter 1.8 (8.0 %); mouth gape 5.4 (24.1 %); interorbital width 1.6 (7.1 %); gill opening 1.9 (8.5 %); isthmus 2.7 (12.1 %); pectoral-fin length 3.2 (14.3 %); pectoral-fin base 1.5 (6.7 %). Body elongate, slender, trunk cylindrical, compressed toward tip of tail; tip of tail hard and pointed; anus anterior to mid-body, tail 1.9 in total length (Fig. 1 ).

Head relatively short, 5.7 in preanal length and 12.0 in TL; contour of head smooth, slightly convex in post-temporal; snout acute and relatively pointed in lateral view, narrow from dorsal side; snout long, prominently projected anteriorly; a distinct groove ventrally of snout; mouth inferior, lower jaw short and tip below middle of base of nostril tube, distance between tips of snout and lower jaw more than eye diameter; anterior nostril tubular, towards ventrally, base of both side closed: posterior rim of tube extending posteriorly, forming a broad flap; inside of tube with two papillae (Fig. 2 A ); posterior nostril a slit opening inside of mouth, concealed by wide dermal flap rolling into mouth completely; eye developed, large, its diameter 2.9 times in snout length; lips smooth without cirri or protrusions, upper lip extending to inner mouth, a curved fold along lower margin of eye; mouth moderate, rictus slightly behind a vertical through posterior margin of eye; interorbital region slightly convex without groove; branchial basket convex; gill opening positioned just anterior to base of pectoral fin.

Teeth small, conical, pointed; no teeth on maxilla and vomer, maxillary region completely covered by an extending upper labial flap (Fig. 3 ); 6 intermaxillary teeth arranged in two rows but concealed by a dermal structure and not visible; dentary teeth uniserial posteriorly, 17 on left side and 15 on right side.

Sensory pores on head obvious (Fig. 4 ); supraorbital pores 1 + 3, 1 ethmoid and 3 pores slightly before a level of center of eye; infraorbital pores 3 + 3, first between anterior and posterior nostrils and second anteroventro-corner of eye, third behind center of eye, and remaining on postorbital; preoperculo-mandibular pores 4 + 2; 3 on supratemporal; 1 interorbital pore present; lateral-line pore slightly obscure, nearly completed except tip of tail equal to one third of HL.

Neurocranium narrow dorsally; dentary stout and recurved; branchiostegal rays developed and deeply overlapped ventrally, 25 in total. Predorsal vertebrae 12, preanal 69, and total 160.

Pectoral fin moderate, shape round, its length 1.6 in snout and 7.0 in HL; medial fins low in height, origin of dorsal fin behind tip of pectoral fin, distance from pectoral fin-tip to dorsal-fin origin 0.6 times of the fin, distance from gill opening to dorsal-fin origin 3.0 in HL; caudal fin absent.

Color in preservation light yellowish brown; abdomen slightly paler but not bicolored distinctly; all fins pale white.

Distribution.

Known only by a single specimen from Dong-gang, southwestern Taiwan. Depth range estimated as more than 100 m.

Etymology.

The specific name diandrus is the Latin compound adjective “bi-stamened”, referring to the flower-like shaped tubular nostril with two papillae inside.

Figures

Figure 1. Phyllophichthus diandrus sp. nov., NMMB-P 28224, holotype, 270 mm TL, Dong-gang, Taiwan A dorsal view B ventral view C enlarged view of lateral head. Arrows indicate origin of dorsal fin (above) and anus (below).

Figure 2. Closed illustration of tubular anterior nostril from ventral view A Phyllophichthus diandrus sp. nov., NMMB-P 28224, holotype, 270 mm TL B P. xenodontus, NMMB-P 5264 (one of two), 373 mm TL, Taiwan. BF broad flap. Arrows indicate papillae inside of nasal tube.

Figure 3. Ventrolateral view of palatal area of Phyllophichthus diandrus sp. nov., NMMB-P 28224, holotype, 270 mm TL. DF dermal flap on posterior nostril LF edge of upper labial flap MR maxillary region VR vomerine region.

Figure 4. Lateral view of anterior head of Phyllophichthus diandrus sp. nov., NMMB-P 28224, holotype, 270 mm TL. AN anterior-nostril tube IO infraorbital pores M mandibular pores PO preopercular pores SO supraorbital pores ST supratemporal pore. Arrows indicate interorbital (left) and mid-temporal pores (right).