Lentipes niasensis Harefa & Chen, 2022

Harefa, Tonisman & Chen, I-Shiung, 2022, A new species of gobiid fish Lentipes niasensis (Gobiidae: Sicydiinae) from Nias Island, Indonesia, Zootaxa 5189 (1), pp. 57-66 : 58-65

Lentipes niasensis Harefa & Chen , new species

Figures 1‒4 ; Tables 1‒2

New English name: Heart-finned goby

Holotype. MZB 25339, male (33.3 mm SL), Humogo River (1°11'30.1"N 97°38'31.8"E), tributary of Idanoi River , Gunungsitoli City , Nias Island , North Sumatera Province, Indonesia; coll. T. Harefa, 17 September 2019.

Paratypes. NTOUP-2019-09-147, 6 specimens (4 males, 2 females, 21.8–29.5 mm SL) same collection data as holotype .

Diagnosis. Distinguished from all congeners by the following combination of features: (1) fin ray counts: D2 I/10; A I/10; P 17–18; D1 not connected to D 2 in either sex. (2) squamation: LR 7–11; anterior half of body naked, lateral scale present from 5–6 th rays of second dorsal-fin to hypural, embedded in skin. (3) upper jaw teeth in male 14–19, in female 33–38. (4) urogenital papilla in male slender and distally pointed, flanked by pair of associated fleshy lobes and not retractable into sheath-like groove. (5) distinctive colour pattern: upper lip greyish, red patches on pectoral-fin base, on mid-body below origin of second dorsal-fin and at caudal peduncle.

Description: Morphometric data given in Table 1 . Body elongated, subcylindrical anteriorly, somewhat compressed posteriorly. Head slightly depressed, snout not protruding. Upper lip thick and more prominent than lower lip. Mouth oblique and posterior end of maxilla extending to vertical through posterior margin of orbit. Anterior nasal opening on short tube and posterior nasal opening a round hole. Gill opening narrow, extending to lower margin of pectoral-fin base. Papillae present around belly and on side of body, starting vertically from anal-fin origin to posterior part of caudal peduncle. Vertebrae count 10+16=26. In male, upper jaw teeth distinctly tricuspid anteriorly (14–19) with recurved canine teeth posteriorly (3–4); in female upper jaw with tricuspid teeth from posterior to anterior (33–38) and no canine teeth. Lower jaw in both male and female usually with recurved canine teeth (5–7). Urogenital papillae in male slender and distally pointed with pair of associated fleshy lobes and not retractable into sheath-like groove ( Fig. 4 ). In female, urogenital papilla somewhat rectangular, also not retractable into sheath-like groove ( Fig 4 ).

Fins. D1 VI, D2 I/10, A I/10, P 17 (in 4 specimens)‒18 (in 3 specimens), V I/5+I/5, C 16 (in 2 specimens)‒17 (in 5 specimens). D1 rays not filamentous, all spinous rays about equal except 6 th spinous ray shortest and rather distant, not connected to D2 basally. Gap between D1 and D2 of about same length as eye diameter in male and much larger in female. D2 without black spot. D2 and A positioned opposite each other, with origin of A directly below 2 nd branched ray of D2. P large, its posterior tip not reaching to vertical though anus. Rear margin of C rounded.

TABLE 1. (Continued)

Scales. LR 7–11, PreD 0, TR 0. Lateral side of anterior half of body without scales. Body scales present from 5–6 th rays of second dorsal-fin through hypural, embedded in skin, with small ctenoid scales dominant anteriorly and cycloid scale generally restricted on caudal peduncle area to hypural.

Head canals and pores. See Fig. 3 . Nasal extension of anterior oculoscapular canal with pore σ located on dorsal side of snout between anterior nostrils. Interorbital region with paired pore λ anteriorly and single pore κ posteriorly. Paired pore α behind posterior edge of eye. Lateral canal section of posterior oculoscapular with pores ρ, θ and τ. Preopercle canal with two terminal pores γ and ε but lacking pore δ.

Head sensory papillae. Infraorbital papillae present as 5 short transverse rows. Row c present as transverse and longitudinal papillae. Row d present above edge of posterior part of mouth. Rows e and i closely arranged. Rows ot, oi, and os well separated on preopercle. Row f paired.

Colour in life. See Fig. 1 . Male, body, snout and nape yellowish to translucent whitish. Upper lip yellowish to greyish. Opercle yellowish to beige with many tiny black dots. Pectoral-fin base reddish with red dots, these sometime merged into heart-shaped marking. Belly white to silver. Black spots on the lower side of body below first and second dorsal-fin. Two pale red blotches on mid-body, first at origin of second dorsal-fin and second at caudal peduncle. Dorsal-fin and anal-fin translucent with scattered black dots on membrane. Pectoral-fin and anal-fin translucent. Second dorsal-fin without round black spot in both sexes. Female, Body translucent. Snout yellowish. Upper lip grey. Opercle beige. Caudal peduncle with tiny black spots. Pectoral-fin base whitish. Dorsal-fin spine and rays with some tiny spots, membrane mostly clear. Caudal-fin whitish and membrane unpigmented. Pelvic-fin also without pigment.

Colour in preservative. See Fig. 2 . Male, body slightly creamy yellow and head greyish with yellowish cheek. Black pigmentation present on operculum. Two dark brown cross-bands below each dorsal-fin. All original red coloration faded to yellowish. Dorsal- and anal-fin greyish with black spots. Caudal-fin whitish. Female, body mostly whitish. Pectoral-fin base whitish. Black pigmentation on operculum. All fins whitish.

Distribution and habitat. Lentipes niasensis is currently known only from the Humogo River, a tributary of the Idanoi River, in Gunungsitoli City, Nias Island, North Sumatera Province, Indonesia. The collection site featured a moderately swift current and rocky substratum. The new species appears to be rare compared to the sympatric Sicyopus zosterophorus Bleeker, 1856 and Stiphodon sp.

Etymology. The specific name niasensis is refer to Nias Island, Indonesia, where the new species collected.

Remarks. S ome meristic and morphological characters of all members of the genus Lentipes are compared in Table 2 . The gobiid fish Raogobius andamanicus Mukerji, 1935 , has also been regarded by some authors as a member of genus Lentipes ( Watson & Allen 1999, Kottelat 2013, Keith et al. 2015), and is therefore included in the table, but further study is necessary to clarify its status (Watson et al. 2001, Keith et al. 2015). With reference on Table 2 , the present new species L. niasensis is distinguishable from L. andamanicus by its second dorsal-fin (10, vs. 9 rays), anal-fin with (10, vs. 12 rays), and pectoral-fin (17–18, vs. 13 rays). The new species, L. niasensis differs from this species as well as L. adelphizonus Watson & Kottelat, 2006 , L armatus, Sakai & Nakamura, 1979 , L caroline Lynch et al., 2013 , L. dimetrodon Watson & Allen, 1999 , L. mindanaoensis Chen, 2004 , L. multiradiatus Allen, 2001 , L. rubrofasciatus Mauge et al., 1992 , L. solomonensis Jenkins et al., 2008 , L. whittenorum Watson & Kottelat, 1994 , L. kijimuna Maeda et al., 2021 , L. bunagaya Maeda et al., 2021 , in not having D1 connected basally to D 2 in the. It is also well distinguished from L. ikeae , L. kaaea Watson et al., 2002 , L. kolobangara Keith et al., 2016 , L. mekonggaensis , L. watsoni , L. palawanirufus Maeda et al., 2021 , by the absence of a round black spot on second dorsal-fin in male. Lentipes niasensis n. sp. is distinguishable from L. concolor Gill, 1860 and L. venustus Allen, 2004 by its possession of a pair of lobes associated with the urogenital papilla in males. Finally, L. niasensis apparently differs from L. crittersius in having more second dorsal-fin ray (10, vs. 9) and fewer pectoral-fin ray (17–18, vs. 19), but the original of L. crittersius was based entirely on the single female holotype ( Watson & Allen 1999) and Keith et al. (2015) noted that additional specimens are required to ascertain its validity.

Lentipes niasensis n. sp. is most similar to L. argenteus from Padang, Sumatra Island, Western Indonesia, in many features. However, it differs from L. argenteus in having a pair of fleshy lobes flanking to the urogenital papilla in males (vs. lobes absent), pore γ (vs. absent) and no pore δ (vs. present and paired); the color pattern of the male: upper lip greyish, red patch on pectoral-fin base, on body midline below origin of second dorsal-fin and at caudal peduncle (vs. upper lip slightly reddish and no red patches); fewer tricuspid teeth in the upper jaw of males (14–19. vs 17–22); fewer lateral scales (7–11. vs 35–49); a relatively longer head in female (22.8–25.7% SL. Vs. 21% SL); a relatively longer length from snout to anal fin origin in females (59.5–62.7% SL. Vs. 51–56% SL); and a relatively greater caudal peduncle depth in both sexes (10.1–10.6. vs. 7–9, in males. and 9.8–10.6% SL, vs. 7% SL, in females).

Comparative materials. Lentipes mindanaoensis : NMMB-P004821 , holotype, 1 specimen (46.0 mm SL), small creeks with swift current in eastern part of Mindanao , Philippines, coll. Adonis P. Porpetcho, February 2003 . Lentipes armatus : NTOU-P 2006-02 - 324 , 1 specimen (34.3 mm SL), the upper tributary, Lan-Len River as branch of Kan-Kou River basin near southern tip of Taiwan, coll. I.S. Chen et al., 10 September 2002 ; NTOU-P 2006-02 - 325 , 3 specimens (35.5–36.3 mm SL), the upper tributary of Lan–Len River as branch of Kankou River Basin near southern tip of Taiwan, coll. I.S. Chen et al., 08 February 2002 ; NTOU-P 2006-02 - 326 , 2 specimens (31.5–35.6 mm SL), the upper reaches of Dong-Chin River of Lanyu (Orchid Island) off eastern coast, Taitung County, Taiwan, coll. C.C. Han et al., 18 April 2002 ; NTOU-P 2006-02 - 327 , 1 specimen (37.2 mm SL), the upper reaches of Dar-Niao River from the Hai-Ang Mountain Ridge, Taitung County, Taiwan, coll. C.C. Han, 30 November 2004 .

Figures

FIGURE 1. Photographs of freshly collected, living Lentipes niasensis n. sp (NTOU-P 2019-09-147, Paratypes) from Humogo River, Nias Island, North Sumatera Province, Indonesia. A. Male (26.0 mm SL); B. Male (22.8 mm SL); C. Female (25.9 mm SL) (Photographs by T. Harefa).

FIGURE 2. Alcohol-preserved specimens of Lentipes niasensis n. sp.A. MZB-25339, holotype, male (33.3 mm SL) B. NTOUP- 2019-09-147-, Paratype, female (29.5 mm SL) (Photographes by T. Harefa).

FIGURE 3. Head lateral-line system of Lentipes niasensis n. sp from Nias Island. MZB25339, holotype male, 33.3 mm SL (scale bar= 1 mm). AN, anterior nostril; PN, posterior nostril. The arrow denotes the position of the gill opening.

FIGURE 4. Diagrammatic sketches of urogenital papilla of Lentipes niasensis n. sp. from Nias Island. Up: female, Down: male. 1. anus, 2. urogenital papilla, 3. anal fin, 4. fleshy urogenital lobe.