Sicyopus lord, Keith & Marquet & Taillebois, 2011

Keith, Philippe, Marquet, Gerard & Taillebois, Laura, 2011, Discovery of the freshwater genus Sicyopus (Teleostei: Gobioidei: Sicydiinae) in Madagascar, with a description of a new species and comments on regional dispersal, Journal of Natural History 45 (43 - 44), pp. 2725-2746 : 2729-2742

Sicyopus lord sp. nov.

( Figures 1 , 2 ; Tables 1–4)

Material examined

Seven specimens from Madagascar, totalling three males, four females; size range 35.2–47.4 mm SL (40.8–56.7 mm, total length), largest male 39.2 mm SL, largest female 47.4 mm SL .

Holotype MNHN 2010-0925 , male (37.2 mm SL), Ambodiforaha River , altitude: 50 m, 14 May 2010, G. Marquet, T. Robinet, Roger and H. Grondin.

Paratypes MNHN 2010-0926 , 1 male, 1 female, size range 35.2–35.9 mm SL; same data as Holotype . MNHN 2010-0927 , female, 47.4 mm SL; Manoumpana River , April 2004 , ARDA. MNHN 2010-0953 , 1 male, 2 females, size range 39.3–44.9 mm SL; Andraka River , 16–18 May 2010, G. Marquet , T. Robinet, Roger and H. Grondin .

Diagnosis

A Sicyopus species which is distinguished from all the other species with the following set of characters: (i) a particular colour pattern, being similar in both sexes with three blackish bands present on the flanks: the first band extends from the tip of snout and upper lip, under the eye to the posterior edge of operculum and pectoral base, and from pectoral base to hypural; the second extends from behind the eye to the caudal fin; and the third runs along the upper part of flank from above the pectoral fin to the second dorsal fin base; (ii) a second dorsal fin with nine soft rays; (iii) a shorter caudal fin length in male; (iv) more scales in lateral series (35–43) and transverse back scale series (12–18).

Description

Scale counts in S. lord sp. nov. and related species are given in Table 2, number of upper jaw teeth in Table 1, morphometrics in Table 3 and fin length in Table 4. Below, the holotype counts are given first, followed, in brackets if different, by the paratypes’ counts.

Dorsal fins D VI–I, 9, spines slightly filamentous in males and less so in females, spines 3 and 4 longer. First dorsal fin not contacting second dorsal fin basally (when depressed). Anal fin I, 10. Pectoral fin rays 15. Caudal fin with 13 branched rays with posterior margin slightly rounded. Pelvic disc with one spine and five strongly branched rays. Scales in lateral series 35 (35–43) ( Table 2); scales may extend midlaterally over the origin of first dorsal fin in male and second dorsal fin in female, and posteriorly to hypural base. Scales usually ctenoid from hypural base to origin of the second dorsal fin and cycloid elsewhere. Scales along dorsum usually extending anteriorly along medial base of second dorsal fin (may extend to base of first dorsal fin). Scales in zigzag series 7 (6–10), transverse back series 13 (12–18), transverse forward series 13 (11–16) ( Table 2). Predorsal midline naked. Head, breast and pectoral base usually naked. Belly usually naked or with few cycloid scales. Upper jaw teeth mostly conical in the female with more and shorter teeth (10–15) than male (7–9) (mostly caniniform). Lower jaw teeth conical in female (range 7–9) and males (4–6) ( Table 1). Notes: M, male; F, female.

(Continued) S. lord 1 2 1 1 1 1 S . discordipinnis 1 2 3 3 4 3

S. jonklaasi 1 3 4 5 6 3 – 1 – – 1 S. zosterophorum 1 – 5 5 5 11 5 5 7 5 1 S . auxilimentus 1 1

S. multisquamatus 1 S. exallisquamulus 1 3 – 2 1 1 – – 1 1

S. cebuensis 1 1

Zigzag scales

6 7 8 9 10 11 12 13

S. lord 1 3 1 1 1

S. discordipinnis 15 2

S. jonklaasi 1 12 8 4

S. zosterophorum 20 30 3

S. auxilimentus 1 1

S. multisquamatus 1

S. exallisquamulus 4 5 1

S. cebuensis 1 1

S. lord 1 4 2

S. discordipinnis 5 6 4 2 1 1

S. jonklaasi 5 4 6 7 3 S . zosterophorum 1 – 1 8 18 19 7

S. auxilimentus 2

S. multisquamatus 1

S. exallisquamulus 2 5 4

S. cebuensis 1 1

(Continued)

Notes: M, male; F, female.

Cephalic sensory pore system A, B, C, D, F, H, K, L, N and O, D singular, with all others paired, oculoscapular canal separated into anterior and posterior canals between pores H and K ( Figure 1 ). Urogenital papilla in male long and thin with fairly pointed to rounded tip. Urogenital papilla in female with two rounded lobes.

Colour in preservation

The sexual dichromatism is not well developed. Background of head and body greyish. Body greyish dorsal to midline. Head greyish dorsally with small blackish dots. A blackish band extending from the tip of snout and upper lip, under the eye to the posterior edge of operculum and pectoral base, and from pectoral base to hypural. Head whitish under this band and ventrally. Blackish horizontal band above the pectoral fin to the second dorsal fin base. Snout blackish. Nape greyish. Faint and thin blackish band extending from pectoral base to caudal fin along body midline. First and second dorsal fin hyaline, with several blackish dots. Dorsal fin spines highlighted by black pigments. Caudal fin dusky to greyish, with three to four vertical blackish bands. Anal fin dusky to hyaline with black pigments. Pelvic disc entirely white. Pectoral fin dusky becoming whitish dorsally and ventrally. Pectoral base blackish medially, slightly dusky ventrally and dorsally.

Colour in life

The sexual dichromatism is not well developed.

Body dusky to slightly yellowish. Three horizontal blackish bands on the flanks. The first one from the tip of snout and upper lip, under the eye, to the posterior edge of operculum and pectoral base, and from pectoral base to hypural. Colour above this band iridescent gold in the last third of the body. Second black band from the back of the eye to the caudal fin. Third one along the upper part of flank from above the pectoral fin to the second dorsal fin base. Dorsal and anal fins dusky to hyaline with black pigments on the rays. Caudal fin greyish with three to four vertical blackish bands. Pectoral fins hyaline.

Belly of male fish whitish to greyish ( Figure 2A ); belly bright orange in gravid female fish ( Figure 2B ).

Ecology

Like other Sicydiinae (see Keith 2003), S. lord is found in clear, high-gradient streams with rocky bottoms. It lives on the bottom of the river, on top of rocks, but it is also often seen swimming in open water in the current between rocks or in large pools. This new species is supposed, like the other Sicyopus , to be amphidromous ( Keith et al. 2008; Lord et al. 2010).

Distribution

Sicyopus lord is known from streams of northeastern Madagascar above an altitude of 20–80 m. Its status is unknown but the species is probably rare, as few specimens have been seen in the area surveyed.

Comparisons

Sicyopus lord differs from all other Sicyopus in having a particular colour pattern, similar in both sexes, with three blackish bands on the flanks. The first band extends from the tip of snout and upper lip, under the eye to the posterior edge of operculum and pectoral base, and from pectoral base to hypural; the second extends from behind the eye to the caudal fin; the third one runs along the upper part of flank from above the pectoral fin to the second dorsal fin base. In other Sicyopus species , there is welldeveloped sexual dichromatism with bright colours in males. Sicyopus lord also differs from all other Sicyopus in having a shorter caudal fin in male (it represents 16–18% of the SL versus 19–29% SL for the other Sicyopus ). Moreover, it differs from S. auxilimentus , S. exallisquamulus and S. cebuensis in having more scales in lateral series (35–43) compared with, respectively, 20–23, 18–21 and 26–27 and from S. exallisquamulus , S. cebuensis and S. zosterophorum in having more scales in transverse back series (12–18) compared with, respectively, 5–8, 8–9 and 10–12. It differs from S. multisquamatus in having a second dorsal fin with nine soft rays rather than 10 and fewer scales in zigzag series (6–10 compared with 13), and from S. jonklaasi and S. discordipinnis in having a first dorsal fin with six spines in females versus five spines.

Key to Sicyopus species

1. Second dorsal fin with 10 soft rays (I10); more than 45 scales in lateral series................................................ S. multisquamatus

Second dorsal fin with nine soft rays (I9); fewer than 45 scales in lateral series................................................................... 2

2. More than 29 scales in lateral series.................................3

Fewer than 28 scales in lateral series................................ 4

3. Caudal fin length of male equivalent to 16–18% of the standard length (SL); no sexual dichromatism...................................... S. lord

Caudal fin length of male equivalent to 19–29% of the SL; sexual dichromatism with bright colours in males...................................... 5

4. More than 25 scales in lateral series; second dorsal fin length equivalent to 25–30% of the SL....................................... S. cebuensis

Fewer than 25 scales in lateral series; second dorsal fin length equivalent to 30–45% of the SL.............................................. 6

5. First dorsal fin of females with six spines; caudal fin length equivalent to 24–29% of the SL.................................. S. zosterophorum

First dorsal fin of females with five spines; caudal fin length equivalent to 17–23% of the SL.............................................. 7

6. Nine to ten scales in zigzag series....................... S. auxillimentus

Six to eight scales in zigzag series..................... S. exallisquamulus

7. Male brownish to yellowish with bright red lips; jaw length equivalent to 8–10% of the SL....................................... S. jonklaasi

Male reddish from second dorsal fin to hypural; jaw length equivalent to 10–11% of the SL.................................... S. discordipinnis

Etymology

The new species is named after our friend Clara Lord, for her extensive and enthusiastic work on Sicydiinae , and is defined as a noun in apposition.

Figures

Figure 1. Diagrammatic illustration of the head in Sicyopus lord (MNHN 2010-0953) showing head pores and sensory papillae. (A) Dorsal view; (B) lateral view. Scale bars, 5 mm.

Figure 2. Sicyopus lord, (A) male in vivo (holotype, MNHN 2010-0925) (photo: T. Robinet- DIAMSOI); (B) mature female in vivo (paratype, MNHN 2010-0953) (photo: T. Robinet- DIAMSOI).