Sicyopterus elomionearum, Lord & Keith & Causse & Amick, 2020

Lord, Clara, Keith, Philippe, Causse, Romain & Amick, Peter, 2020, A new species of Sicyopterus (Teleostei: Gobioidei: Sicydiinae) from Papua New Guinea, Cybium 44 (2), pp. 127-136 : 131-135

Sicyopterus elomionearum n. sp.

( Figs 2-5 , Tabs II-V)

Diagnosis

A Sicyopterus with 3 clefts (one anteriorly and 2 midlaterally) on upper lip, with smooth lip and with a second dorsal fin with 1 spine and 10 segmented rays. Courting male coal black with a pearl white necklace. 63-69 scales in lateral series, 27-33 in transverse forward and 21-23 in transverse back series.

Known and described from 10 specimens from streams of West New Britain, Papua New Guinea, totalling 6 males and 2 females, size range 23.6-82.2 mm SL.

Material examined

Holotype. – MNHN 2019-0107 (tag MP-10634), male, 69.4 mm SL. Elnge Creek , New Britain ( Papua New Guinea), 12 Nov. 2015, Amick et al. coll.

Paratypes. – MNHN 2019-0108 (tags MP-12801, MP-12802), 1 male, 1 female, size range 41.8-43.7 mm SL. Bereme village , Huvenganga River , 19 Oct. 2018, Keith et al. coll. MNHN 2019-0109 (tag MP-17822, MP-17824, MP-17825, MP-17601, MP-17603), 4 males, 1 female, size range 23.6-27.1 mm SL. Bereme village , Galuku River , 20 Oct. 2018, Keith et al. coll. MNHN 2019-0110 (tags MP-10565, MP-10570), 1 male, 82.2 mm SL, 1 female, 81.9 mm SL. Same data as holotype, Amick et al. coll .

Description Scale counts are given in table II, morphometrics in table III and fin length in tables IV and V. Below, the holotype counts are given first, followed in brackets, if different, by the paratypes’ counts.

Dorsal fins VI-I,10; the first dorsal fin has the third and fourth rays slightly filamentous, usually reaching to one third of the length of the second dorsal fin base in males, with the third ray longer; not reaching the second dorsal fin in females. Anal fin I,10 directly opposite to the second dorsal fin. Caudal fin with 15-16 branched rays and posterior margin rounded. Pelvic disk with 1 spine and 5 branched rays on each side, fifth rays joined together over their entire length, a strong frenum between spines, disc adherent to belly between all 5 rays. Pectoral fins usually 19-21, posterior margin rounded. LS 67 (63-69), PD scales 40 (22-32). Small cycloid scales on head, nape, flanks; belly entirely covered with cycloid scales, extending from anus, almost to pelvic fin base. Well-developed ctenoid scales on the rest of the body. TRB 23 (21-22). TRF 33 (27-32). ZZ 19 (18-19). Upper jaw with a single row of flexible tricuspid teeth (60-97), lateral cusps rounded, medial cusps shorter than lateral cusps and sharply pointed. Dentary with a single straight row of conical teeth 12 (2-8) on each side, not curved and not meeting at symphysis; anterior and posterior teeth usually caniniform; horizontal teeth correspond in position with upper jaw teeth. Upper lip smooth with 3 clefts (one anteriorly and 2 midlaterally). Lower lip mostly absent, rudimentary elements present as expanded and folded tissue posterior to lower jaw teeth. Cephalic sensory pore system A, B, C, D, F, H, L, M, and N. Pore O absent. Pore D singular with all others paired. Oculoscapular canal uninterrupted posterior to eye. Cutaneous sensory papillae present on head ( Fig. 2 ).

Males with triangular urogenital papilla with distal tip rounded. Females with bulbous urogenital papilla with fimbriate projections around distal opening ( Fig. 3 ).

Colour in preservation

Female and male body uniformly greyish to brownish ( Fig. 4 ). Throat, pelvic fins and belly white. The pectoral fins are dark grey. The first and second dorsal fins are a translucent grey. Caudal fin grey. Anal fin translucent with a black margin. Black tear under the eye. Males develop specific colours during courtship: body entirely dark brown with lighter brown pectoral and caudal fins. Two dorsal and anal fins black. Head dark brown from snout to preoperculum. Nape, operculum, throat and pelvic disc white, as if male was wearing a necklace.

Colour in life

Body dusky grey with 3 to 4 Y-shaped lighter grey marking along the sides. Belly white to greyish. Dorsal fins hyaline to translucent. Pectoral fins brown. Caudal fin greyish to brownish. Anal fin hyaline with black margin. Head dark and usually with a black tear under the eye. There is a sexual dichromatism; males in courtship are coal black, with black dorsal and anal fins. Pectoral fin base black becoming brownish on the edge. Caudal peduncle black with whitish markings on caudal fin. Operculum, throat, pelvic sucker, and sometimes nape, pearly white, as if male was wearing a necklace ( Fig. 5 ).

Ecology

Paratype specimens were caught in small streams in the vicinity of Bereme village, West New Britain Island. The streams were narrow (about 3 m wide), well imbedded in the tropical rainforest with tall trees and native vegetation keeping the stream in the shade. The habitat consists of clear, well-oxygenated water, running through large boulders on a gravel and sand bottom ( Fig. 6 ). The current was slow to moderately fast; temperature and pH values of 24.4-25°C and 8, respectively were recorded.

Distribution

Sicyopterus elomionearum n. sp. is currently known only from several streams in West New Britain Island, Papua New Guinea (Elnge Creek, Huvenganga River, Galuku River and their tributaries). It co-occurs with Sicyopterus cynocephalus (Valenciennes, 1837) , Sicyopterus stiphodonoides Keith, Allen & Lord, 2012 , Sicyopterus lagocephalus (Pallas, 1770) and Sicyopterus longifilis de Beaufort, 1912 .

Etymology

Sicyopterus elomionearum is a name given to honour the first author’s two daughters, Eloïse and Hermione. Indeed the first author would like to thank them for letting her leave on inventory missions for lengthy periods and also wishes to salute their great interest in their mother’s work. Because we considered that “Elomione”, born from the contraction of Elo ïse and Her mione, represents two persons, we used the plural form elomionearum for the species name.

Figures

Figure 2. – Diagrammatic illustration of head in Sicyopterus elomionearum n. sp. showing cephalic sensory pore system and cutaneous sensory papillae. A: Dorsal view; B: Lateral view; C: Ventral view.

Figure 3. – Diagrammatic illustration of urogenital papilla in Sicyopterus elomionearum n. sp. (ventral view): 1. anus; 2. urogenital papilla; 3. anal fin. A: Male; B: Female.

Figure 4. – Sicyopterus elomio- nearum, Paratypes, MNHN 2019-0108. A: Female, SL 41.8 mm; B: Male, SL 43.7 mm. Bereme village, Huvenganga River, West New Britain Island, Papua New Guinea, 19 Oct. 2018, Keith et al. coll.

Figure 5. – Sicyopterus elomionearum, Holotype, MNHN 2019-0107 (tag 10634), male, 69.4 mm SL. Elnge Creek, New Britain (Papua New Guin- ea), 12 Nov. 2015, Amick et al. coll.

Figure 6. – Photos of the type locality of the paratype specimens of Sicyopterus elomionearum. A: Huvenganga River, West New Britain Island, Papua New Guinea (Paratypes, MNHN 2019-0108); B: Galuku River, West New Britain Island, Papua New Guinea (Paratypes, MNHN 2019-0109).