Giuris tolsoni (Bleeker, 1854)

Keith, Philippe, Mennesson, Marion I., Sauri, Sopian, Busson, Frédéric, Delrieu-Trottin, Erwan, Limmon, Gino, Nurjirana, Dahruddin, Hadi & Hubert, Nicolas, 2020, Giuris (Teleostei: Eleotridae) from Indonesia, with description of a new species, Cybium 44 (4), pp. 317-329 : 324-325

Giuris tolsoni (Bleeker, 1854)

( Figs 1 , 3 ; Tabs II-III)

Material examined

Holotype. – RMNH 5180 (1 of 17), Near Djung-Kulon (Djunkulon), extreme western Java, Indonesia.

Others. – MZB.25328, Bali, West Bali, Kab Jembrana, Nbang, 15 Apr. 2014, Hubert et al. coll.; BIF 2283 . – MZB.25329, Bali, West Bali, Kab Kelungkung, Tukad Unda, 22 Apr. 2014, Hubert et al. coll.; BIF 2846 to BIF 2850 . – MZB.25330, 24 Apr. 2014, Bali, West Bali, Kab Tabanan, Tukad Balian , Hubert et al. coll.; BIF 2962 . – MZB.25331, Lombok, Lombok Utara, Kali Sidutan, 2 Apr. 2015, Hubert et al. coll.; BIF 4040 . – MZB.25332, Lombok, Lombok Utara, Sidutan, 28 March 2015, Hubert et al. coll.; BIF 3790 & BIF 3792 .

Description

The scale and ray counts are given in table II and morphomeristic data in table III.

The body is more ovoid than elongated. The body depth at anus is 16-22 (% SL), at first dorsal fin 20-24 (% SL), and the caudal peduncle depth is 13-15 (% SL). Predorsal length 39-47 (% SL) and preanal length 59-68 (% SL). Size: up to 11 cm SL.

The head (31-37% SL) is depressed, the snout is convex. The anterior nostrils are short, not reaching upper margin of upper lip. Mouth and jaw length (9-12% SL) small. Inwardly curved teeth set on both jaws and larger on outer row. Posterior end of maxillary extending to below around anterior margin of eye. Lips with numerous internal short papillae, large and bifid in several specimens. Eye diameter 6-7 (% SL), and interorbital length small (9-12% SL).

Dorsal fins VI-I,8 without filamentous rays. The first dorsal fin is with second, third and fourth rays longer. Anal fin I,9 directly opposite to the second dorsal fin. The caudal fin is with 13-15 branched rays and its posterior margin is rounded. Pelvic fins separate, I,5. Pectoral fins 14, with the posterior margin rounded. Lateral scales 29-31, with ctenoid scales on flanks and caudal peduncle. Cycloid scales from snout to top of head and anterior part of D1, on operculum, on base of pectoral fins and on belly extending to anus. Scales of top of head and back greater than those of belly. Scales in transverse back series 10-11, in transverse forward 13-16, in predorsal 14-16 and in zigzag 8-10. 6-9 scales around the eye. 25 vertebrae.

Absence of oculoscapular canal and supratemporals and presence of a short preopercular canal with pores N’ and O’.

Cephalic sensory papillae system developed as described by Akihito et al. (1988).

Males with a rounded/triangular urogenital papilla with distal tip rounded. Females have a bulbous urogenital papilla with fimbriate projections around distal opening.

Colour in preservation ( Fig. 3A )

Male and female similar. Background of body and head brown to beige. Lateral part brownish with, for several specimens, 1-3 brown stripes radiating from the eye to the cheeks and operculum and four to five longitudinal parallel rows of aligned small brownish dots, or a dark longitudinal and medium brown band from pectoral to hypural base. The fins are greyish to beige.

Colour in life

Males ( Fig. 3B ). – Male with background of body light brown on the back to bright beige and yellow on the flanks. Belly white. Top of head brownish, with several small reddish dots, lateral part greyish to bluish with 3 thin red stripes radiating from the eye to the cheeks and operculum, the first or two highest continuing on the pectoral base. Four to five longitudinal parallel rows of aligned small red dots, alternating with blue and yellow parts. Sometimes the medium row forms a continuous line from pectoral base to hypural base. The first dorsal fin is translucent with yellow stripes in the medium part. The second dorsal and anal fins are yellowish at the base and hyaline at the distal half with a thin white stripe at the distal tip. Pectoral, pelvic and caudal fins hyaline.

Females ( Fig. 3C ). – background of body light brown on the back to bright beige on the flanks. Top of head brownish, lateral part greyish to bluish with 3 thin red stripes radiating from the eye to the cheeks and operculum, the first or two highest continuing on the pectoral base. Small alternating reddish to bluish rounded patches along the flanks from pectoral base to hypural base, forming a medium straight or sinuous band. Belly whitish as the lower part of the flanks. The first dorsal fin is translucent. The second dorsal fin is slightly greyish with a thin white stripe at the distal tip. Pectoral fins hyaline. Pelvic fins hyaline with a white distal margin. The anal fin is yellow or grey with a distal white stripe. Caudal fin hyaline.

Ecology

Giuris tolsoni occurs in estuaries and lower parts of coastal streams, usually in riverbank vegetation. It is mostly carnivorous and feeds on small shrimps, insects and fish. It is thought to be amphidromous. In Indonesia it is sometimes found in sympatry with G. margaritaceus or G. viator n. sp. (present paper).

Distribution

Giuris tolsoni is known from Indonesia (Bali, Lombok, Halmahera, Sulawesi), Philippines Japan and Taiwan.

Comparison

Giuris tolsoni differs from the other species sequenced and present in the area by displaying reciprocal monophyly from its closest relatives and high K80+I genetic distances to its relatives at COI gene (0.0556 to its closest relative G. margaritaceus ). Moreover, it differs from Giuris viator n. sp. (present paper) in having fewer scales around the eye (6-9 vs. 10-13), a smaller body depth at anus (16-22 vs. 21-24% SL) and by the colourful pattern of the male. It differs from Giuris margaritaceus , in having fewer scales around the eye (6-8 vs. 8-11), a smaller interorbital length (9-12 vs. 12-14% SL), always 14 pectorals rays vs. 14 or 15 rays, and by the colourful pattern of the male.

Description of the new species

Figures

Figure 1. – Most likely ML tree inferred using the K80+I model (–lnL = 1548.01608, Transition/tranversion ratio = 20.137, I = 0.776). Barcode Index Numbers (BIN) are given for each lineages.

Figure 3. – A: Giuris tolsoni, RMNH 5180, holotype, male; SL 61.5 mm (Photo RMNH, P. Keith). B: G. tolsoni, MZB.25328, male, Bali; BIF 2283; SL 66 mm (Photo N. Hubert). C: G. tolsoni, in MZB.25329, female, Bali; BIF 2848; SL 34 mm (Photo N. Hubert).