Cobitis indus, Eagderi & Secer & Freyhof, 2022

Eagderi, Soheil, Secer, Burak & Freyhof, Jörg, 2022, Cobitis indus, a new spined loach from the Dalaman River in the Eastern Aegean Sea basin (Teleostei: Cobitidae), Zootaxa 5162 (4), pp. 410-420 : 414-419

Cobitis indus , new species

( Figs. 2–5 )

Holotype. NUIC 1708 -M, male, 65 mm SL, Turkey: Denizli prov.: Dalaman River at Alci , 37.1476, 29.1876.

Paratypes. FSJF 4099 , 6 , 43–66 mm SL; NUIC-1708, 15, 43–65 mm SL; data same as holotype .

Material used in molecular genetic analysis. NUIC-1708; same data as holotype (GenBank accession numbers: OM 292591 and OM 292592 ) .

Diagnosis. Cobiti s indus is distinguished from the other Cobitis species in the Dalaman River drainage by a combination of characters, none of them unique. It is distinguished from C. dorademiri by lacking a distinct row of pigments along the lower edge of the caudal pecuncle (vs. usually present), having a more slender body (body depth 14–17 vs. 17–21% SL), and caudal peduncle (cudal pedunce depth 1.2–1.7 times in caudal-peduncle length vs. 1.0- 1.2), Z3 fully covered by very small spots forming a sand-like pattern in female, restriced to one line or a narrow band in male (vs. pigmentation elements in Z3 coarse, not sand-like), Z 4 in front of vertical of dorsal-fin origin with small, often very closely set, horizontally elongated blotches, often fused into a stripe (vs. Z4 usually with large round or squarish blotches; if Z4 with small blotches, then Z4 dissociated into two rows or a band of small blotches and spots, not forming a clear horizontal series or a stripe). The new species is distinguished from C. phrygica by having a deeper body (body depth 14.4–16.7 vs. 12.5–13.8% SL), a bifurcate suborbital spine (vs. simple), a small, bold, comma-shaped black spot at upper caudal-fin base (vs. lacking), and no pigmentation below Z4 (vs. present). Cobiti s indus is distinguished from C. fahireae by having two laminae circularis in the male (vs. one), and from C. afifeae , found adjacent to the north of the Dalaman River, by lacking pigmentation below Z4 or pigmentation below Z4 restricted to the caudal peduncle (vs. pigmentation below Z4 usually present along the complete flank).

Description. See Figures 2–5 for general appearance and Table 3 for morphometric data of holotype and 15 paratypes. A small and slender species. Greatest body depth at or slightly anterior to dorsal-fin origin, decreasing towards caudal-fin base. Head profile slightly convex, head length 1.2–1.5 times in body depth. Snout blunt, 0.7–0.9 times in postorbital length. Interorbital space narrow, slightly convex. Eye diameter 0.2–0.4 times in head depth at eye, 15–19% HL, 0.9–1.9 times in interorbital width. Caudal peduncle 1.2–1.7 times longer than deep. No or a shallow hump at nape. Pelvic axillary lobe present, fully attached to body. Margin of dorsal and anal fins convex or straight. Caudal fin truncate or slightly rounded. A shallow ventral keel on caudal peduncle, dorsal keel absent. Pelvic-fin origin below 2 nd or 3 rd branched dorsal-fin ray. Largest recorded specimen 65 mm SL.

Dorsal fin with 7½–8½ branched rays. Anal fin with 5½ branched rays. Caudal fin with 7+7 (4), 8+8 (12) branched rays. Pectoral fin with 7–8 branched rays and pelvic fin with 5–6 branched rays. Body completely covered by embedded scales, absent on belly and breast. Scales small. Focal area in subdorsal scales small, eccentric, with well-developed radii. Lateral line short, reaching middle or posterior end of pectoral fin. Suborbital spine bifurcate, reaching slightly beyond centre of eye. Mouth small and arched. Lips ( Fig. 5 ) thin, mental lobes of lower lip short, without furrows, usually well separated, not produced into a barbel-like process. Rostral barbel reaching base of mandibular barbel. Mandibular barbel reaching to or slightly in front of vertical of nostril. Maxillary barbel reaching vertical of front border of eye.

Sexual dimorphism. Males have a longer pectoral fin and two laminae circularis (vs. absent).

Colouration. Body pale yellowish-white (in preserved specimens) with a dark-brown pigmentation pattern organised in one mid–dorsal and four lateral zones (Z1–Z4). Head covered with small spots. A narrow stripe running from tip of snout to eye. Mid–dorsal pigmentation consists of a series of 13–18 irregularly shaped small to medium size blotches, 5–10 on predorsal back, usually one at dorsal-fin orgin, one below dorsal-fin base and 5–6 behind dorsal-fin base, some shaped as short saddles, a marbled pattern on back behind dorsal-fin base in few individuals. Z1 and Z2 narrower than Z3. Z1 with small, irregular and merged spots, pigmentation usually not reaching dorsally to interspaces of mid-dorsal blotches, reaching to dorsal-fin base, pigmentation in Z1 fused with pigmentation in Z2 and Z3 on postdorsal flank. Spots in Z2 very densely set, often fused to each other forming short stripes. Pigmentation in Z2 reaching to vertical of anus in some individuals, reaching to caudal peduncle in other individuals. Spots in Z3 very small, irregular shaped, forming a sand-like pattern in female, restriced to one line or a narrow band in some male, reaching to vertical of dorsal-fin base in some individuals, especially in male, to caudal–fin base in large female. Z4 with totally 17–24 blotches, blotches usually small, irregularly shaped, roundish or horizontally elongated in front of vertical of dorsal-fin base, larger and often squarrish or roundish behind. Blotches in Z4 often fused to each other, forming a stripe in some individuals. No pigmentation below Z4 except some small spots at caudalfin base in few individuals. One black, bold, comma-shaped spots at caudal-fin base. Fins yellowish or hyaline in live, hyaline in preserved individuals. Caudal fin with 3–4 and dorsal fin with 5–6 dark brown, sometimes irregular shaped bars. No pigmentation on paired fins. Barbels whitish.

Etymology. The species is named for the Indus, the name of the Dalaman River in classical antiquity. A noun in apposition.

Distribution and Habitat. Cobitis indus is so far known from one place in the middle Dalaman River. At the type locality, the river has a high current velocity and gravel to sandy bottom. Oxynoemacheilus anatolicus , Squalius fellowesi , Barbus xanthos , Vimba vimba and Capoeta aydinensis co-exists at the type locality of C. indus .

Remarks. Molecular data ( Fig. 1 ) place C. indus in the C. simplicispina species group ( C. battalgilae , C. bilseli , C. dorademiri , C. joergbohleni , C. phrygica , C. pirii , C. simplicispina , C. sipahilerae , and C. turcica ). It is distinguished from the other species of the C. simplicispina species group by a combination of characters, none of them unique. Cobiti s indus is distinguished from C. joergbohleni , C. pirii , C. turcica and many inidividuals of C. battalgilae by having 17–24 small blotches in Z4, often fused into a dark-brown stripe (vs. separated or without blotches), and flank in front of the vertical of pelvic-fin base without spots or blotches below Z4 (vs. flank in front of vertical of pelvic-fin base with spots or blotches below Z4). Furthermore, flank pattern of C. indus is well-organised in four Gambetta zones (vs. not organised in Gambetta zones in adult C. joergbohleni , C. turcica and some individuals of C. battalgilae ).

Cobiti s indus is further distinguished from C. joergbohleni by having a bifurcate external part of the suborbital spine (vs. simple), caudal fin with 4–5 dark-brown or black, regular shaped bars (vs. 6–8 sometimes irregular shaped bars). It is further distinguished from C. pirii by having a bifurcate external part of the suborbital spine (vs. simple), and a comma shaped black spot at the uppermost caudal-fin base (vs. very small black point). Cobiti s indus is further distinguished from C. turcica by having a deeper caudal peduncle (3.4–5.2 vs. 2.8–3.7% SL). Cobitis battalgilae has a very variable flank pattern but usually individuals have distinct and well separated large blotches (vs. a row of small, very closely set or fused blotches in C. indus ) or blotches in Z4 are small and densely set in C. battalgilae , then there is not one distinctive row of blotches in Z4, but Z4 is divided in two or more horizontal elements resulting in a colour pattern of two rows of blotches (vs. no row of blotches below Z 4 in C. indus ).

Cobitis indus is distinguished from C. simplicispina by having the pigmentation in Z4 dissociated and reaching to or almost to the ventral midline on the caudal peduncle (vs. pigmentation in Z4 not dissociated at the caudal peduncle), a deeper caudal peduncle (3.4–5.2 vs. 2.5–3.6% SL), and a deeper body at the dorsal-fin origin (14.4–16.7 vs. 12.7–14.0% SL). It is distinguished from C. sipahilerae by the pigmentation pattern on the back consisting of 3–7 large roundish or ovoid, dark-brown blotches (vs. back plain, cream-brown anterior to dorsal-fin origin. In few individuals the plain back is interrupted by 1–3 narrow, dark-brown, squarish bars). Cobitis indus is distinguished from C. evreni by having a black spot at the uppermost caudal–fin base (vs. absent), Z4 organised in series of blotches (vs. one stripe), and having a pelvic axillary lobe (vs. lacking). The new species is distinguished from C. bilseli by having two laminae circularis on pectoral fin in male (vs. one), and Z4 with 17–24 small blotches often fused into a dark-brown stripe (vs. 10–12 large blotches).

The occurrence of four species of Cobitis in the Dalaman River drainage is exceptional. Based on our fieldwork, C. dorademiri is found in the lower part of the River sympatric with C. fahireae and C. phrygica is only found in the upper Dalaman and in streams around Lake Gölhisar. Cobitis indus inhabits the main channel of the river in the middle part of the Dalaman River but it remains unclear if it migh be more widely distributed and potentially be sympatric with one or more of the other species.

Figures

FIGURE 1. The Bayesian Inference (BI) phylogenetic relationships within the studied Cobitis based on the mitochondrial COI barcode region. Values at nodes correspond to BI posterior probability/ML bootstrap. Numbers after each species name corresponds to GenBank accession number on Table 1 (Solid bars right to the specimen labels indicate species delimitation results from PTP except outgroups).

FIGURE 2. Cobitis indus, NUIC 1708–H, holotype, 65 mm SL; Turkey: Dalaman River at Alci.

FIGURE 3. Cobitis indus, paratypes; (a) NUIC 1708–2, female, 55.5 mm SL; (b) NUIC 1708–5, female, 64 mm SL; Turkey: Dalaman River at Alci.

FIGURE 4. Cobitis indus, paratypes; (a) NUIC 1708–2, female, 55.5 mm SL; (b) NUIC 1708–5, female, 64 mm SL; Turkey: Dalaman River at Alci.

FIGURE 5. Cobitis indus, paratypes; (a) NUIC 1708–2, female, 55.5 mm SL; (b) NUIC 1708–5, female, 64 mm SL; Turkey: Dalaman River at Alcı.