Glyptothorax daemon, Freyhof & Kaya & Abdullah & Geiger, 2021

Freyhof, Jörg, Kaya, Cüneyt, Abdullah, Younis Sabir & Geiger, Matthias F., 2021, The Glyptothorax catfishes of the Euphrates and Tigris with the description of a new species (Teleostei: Sisoridae), Zootaxa 4969 (3), pp. 453-491 : 482-487

Glyptothorax daemon , new species

( Fig. 31–36 )

Holotype. FFR 3928, 125 mm SL; Turkey: Hakkari prov.: stream Dilektaşı 16 km northeast Yüksekova, 37.6664 44.1393.

Paratypes. FFR 3926, 9, 73–116 mm SL; FFR 3905, 10, 70–110 mm SL; same data as holotype. —FSJF 3962, 10, 71–111 mm SL; Iraq: stream Choman at Qubay Galala, 36.6106 44.8381 .

Additional materials examined. FFR 3902, 1, 103 mm SL; Turkey: Bitlis prov.: stream Gümüşkanat at Gümüşkanat , 38.4028 41.7394 .— FFR 3904, 10, 53–90 mm SL; FFR 3918, 9, 65–115 mm SL; Turkey: Hakkari prov.: stream Eziki 6 km northeast Konak , 37.6717 43.8628 .— FFR 3907, 5, 76–103 mm SL; FFR 3920, 3, 79–100 mm SL; Turkey: Bitlis prov.: stream Çıratan 3 km southwest of Üçadım , 38.3547 41.7814 .— FSJF 3677, 2, 78–91 mm SL; Turkey: stream Çıratan about 5 km east of Gümüşkanat , 38.3846 41.7818 .

Material used in molecular genetic analysis. FSJF-DNA 2636-2637; Iraq: stream Choman at Qubay Galala , 36.6106 44.8381 (GenBank accession numbers: MW770724,MW770725,MW770730,MW770733, MW770732 ) .— FSJF-DNA 2673; Turkey: stream Çıratan about 5 km east of Gümüşkanat , 38.3846 41.7818 (GenBank accession numbers: MW770713, MW770729 ) .— FSJF-DNA 3337; Turkey: Hakkari prov.: stream Eziki 6 km northeast Konak , 37.6717 43.8628 (GenBank accession numbers: MW724514, MW724515, MW724516 ) .— FSJF-DNA 3338; G559F Turkey: Hakkari prov.: stream Dilektaşı 16 km northeast Yüksekova , 37.6664 44.1393 (GenBank accession numbers: MW724512, MW724513, MW724517, MW770722 ) .— FSJF-DNA 3339; Turkey: Bitlis prov.: stream Çıratan 3 km southwest of Üçadım , 38.3547 41.7814 (GenBank accession numbers: MW724518, MW724519, MW724520 ) .

Diagnosis. Glyptothorax daemon is distinguished from its congeners in the Euphrates and Tigris drainages by a combination of characters, none unique to the species. Glyptothorax daemon is distinguished from G. armeniacus by having very indistinct or no yellow tips of the fins (vs. with distinct yellow tips), many shallow warts on the head giving the skin a wary appearance (vs. many minute tubercles and few warts). It is distinguished from G. silviae by having many warts on the back and flank (vs. absent), well developed and numerous anteromedial striae in the thoracic adhesive apparatus (vs. absent or very short), and many black, dark-grey or dark-brown spots and/or blotches on the flank (flank with few scattered dark-brown spots).

The new species is distinguished from G. cous , G. kurdistanicus and G. steindachneri by having the dorsal and lateral head without tubercles (vs. many large, elongated, bony and striated tubercles in G. cous and G. steindachneri ); a strongly elevated thoracic adhesive apparatus (vs. not or very slightly elevated in G. cous ), 1.1–1.3 times longer than wide (vs. 0.8 – 1.1 in G. cous , 0.7 – 0.9 in G. kurdistanicus ), extending from the isthmus to the base of the last pectoral-fin ray or to the posterior limit of the pectoral-fin base (vs. to base of first or third branched pectoral-fin ray in G. kurdistanicus ). The thoracic adhesive apparatus is well delineated at its posterior margin (poorly delineated in G. cous ), completely situated on the horseshoe shaped swelling (vs. extending beyond the swelling, usually onto the pectoral-fin base in G. cous ). It is further distinguished from G. steindachneri by having a short adipose-fin, its length 0.7–1.1 times (vs. 1.5–3.0) larger than the distance between the base of last dorsal-fin ray and the adipose-fin origin, the medial pit without striae (with striae), a blunt and roundish head, its length 24–26% SL (vs. pointed, 21–23), and 7–11 serrae on the inner margin of the pectoral-fin spine (vs. 13–17).

Description. Morphometric data in Table 4 . Head depressed; body subcylindrical. Dorsal head profile straight, predorsal profile slightly convex: Profile rising from tip of snout to dorsal-fin origin, then almost straight, sloping gently ventrally from origin of dorsal fin to end of caudal peduncle. Ventral profile straight to end of caudal peduncle. Caudal-peduncle depth 1.6–2.1 times in its length. Anus and urogenital openings located below tip of adpressed pelvic fin. Skin of back and flank with small, roundish warts, sparsely set on head, densely set on flank and belly, warts larger and more distinct on belly. Lateral line complete and midlateral. Head broad, spade-shaped when viewed laterally. Snout blunt. Anterior and posterior nares large and separated only by base of nasal barbel. Bony elements of dorsal surface of head covered with thick skin, smooth, without tubercles, with many warts, slightly elongated on gill cover ( Fig. 34 ). Eye ovoid, horizontal axis longest; located just below dorsal-head profile. Largest individual recorded 125 mm SL.

Barbels in four pairs. Maxillary barbel broad and thick, extending to, slightly in front of or beyond pectoral-fin base, velum at proximal part of barbel attached to head closer to posterior nare than to eye, many thick warts on outer base of velum, velum smooth. Nasal barbel broad, extending almost to anterior orbital margin. Inner mandibularbarbel extending to isthmus. Outer mandibular barbel extending to end of gill cover, not reaching pectoral-fin origin. Mouth inferior, premaxillary tooth band partially exposed when mouth is closed. Oral teeth small and villiform, in irregular rows on all tooth-bearing surfaces. Premaxillary teeth appearing in single broad semilunate band. Dentary teeth in a single crescentic band, consisting of two separate halves tightly bound at midline.

Thoracic adhesive apparatus consisting of keratinised striae in an elongate oblong field extending from isthmus to almost posterior limit of pectoral-fin base ( Fig. 33 ); anterolateral edges of adhesive apparatus slightly convex, often almost straight; its width 1.1–1.3 times in its length; completely situated on a horse-shoe shaped swelling, associated with few, small warts at its lateral edge and without warts at its posterior edge. Anteromedial striae present and well developed. Narrow, spear-blade shaped medial pit on posterior half of thoracic adhesive apparatus. Dorsal fin located above anterior third of body, with 6 (10) branched rays; fin margin straight or slightly concave; spine short and straight, smooth on anterior and posterior margin; distal 1/3 poorly ossified and soft. Adipose fin with anterior margin straight or slightly convex and posterior margin roundish; its origin at vertical through or very slightly in front of anal-fin origin. Caudal fin with rounded lobes, lower lobe slightly longer than upper lobe and i,8+7,i (10) principal rays. Anal-fin base vertically opposite adipose-fin base. Anal fin with slightly convex anterior margin and straight or slightly concave or convex posterior margin; with 7 (8), or 6 (2) branched rays. Pelvic-fin origin at vertical through or slightly in front of or behind tip of adpressed dorsal fin. Pelvic fin with slightly convex anterior margin and I,5 (10) rays; tip of adpressed fin reaching anal-fin origin. Pectoral fin with I,8 (10) rays; posterior fin margin straight; anterior spine margin smooth, with many unculi and a honey-comp pattern on lower surface, inner margin with 7–11 serrae. Back anterior to adipose fin flat or slightly rounded, with a shallow keel in some individuals, expanded distal tips of neural spines not forming a series of bumps.

Coloration. In 70% ethanol: dorsal and lateral surfaces of head and body dark-grey to greyish brown, fading to pale-grey or beige on ventral surfaces of head and anterior belly and on pectoral and pelvic-fin bases. Dorsal and lateral surfaces of head and body with small irregular spots and / or small blotches slightly darker than background coloration. Spots smaller than eye diameter, blotches as large as eye or slightly larger. Latero-sensory pores same colour as surrounding tissue. A pale-grey blotch at dorsal-fin origin. Adipose fin with a pale-grey blotch behind origin and a pale-grey posterior margin. All other fins with a proximal dark-grey to blackish base, followed by a pale-grey band, then a dark-grey band and a hyaline or pale-grey margin; appearing as dark-grey or blackish fins with a whitish band and margin; whitish margin in caudal fin often absent or reduced to a large or small blotch on each lobe. Pattern in fins dissociated and lost in large individuals. Maxillary and nasal barbels grey or blackish dorsally, pale-grey ventrally and velum pale-grey or beige. Mandibular barbels beige or pale-grey.

Etymology. The specific epithet is latinised from the Greek adjective δαίμων usually interpreted as a ghost. A noun in apposition.

Distribution. Headwater streams in upper Tigris and Great Zab drainage in Turkey and Iraq.

Habitat. Glyptothorax daemon is found in upland rivers and streams with fast current and a substrate composed predominantly of rocks and gravel.

Remarks. The four populations of G. daemon examined for this study are sorted into two molecular groups with a minimum K2P distance of 2.0% in their DNA barcode sequence. We were unable to distinguish fishes from these two molecular groups by the morphological characters examined and therefore treat them as conspecific. Indeed, this is a very surprising situation as all sequenced individuals of G. cous cluster as sister to one G. daemon group with a K2P distance of 1.2% between them. While a K2P distance of 2.0% between populations of a fish species quite specialised for torrent headwaters is not a surprise, the close relationship of G. daemon with G. cous is. Potentially, G. daemon had hybridised with G. cous and at least some populations carry the mtDNA of G. daemon as an indicator of a past introgressive hybridisation. Therefore, we would expect that fish identified as G. cous by morphological characters but having quite different mtDNA might be found in the future.Alternatively, both species are just very closely related. With only mitochondrial COI data available, the phylogenetic relationship between G. daemon and G. cous cannot be resolved. We therefore regard it more appropriate and parsimonious to identify both populations as G. daemon than to describe an additional species, only distinguished from G. daemon by a K2P distance of 2.0% without any additional support from morphology or (unstudied) nuclear DNA sequences. Only a study on nuclear DNA could exclude the possibility of an introgressive hybridisation and clarify the phylogeny of this group. We do not identify G. daemon to be conspecific with G. cous , as both species are very well distinguished morphologically.

Figures

FIGURE 31. Glyptothorax daemon, FFR 3928, holotype, 125 mm SL; Turkey: stream Dilektaşı.

FIGURE 32. Glyptothorax daemon, FSJF 3962, paratypes; from top: 84 mm SL, 101 mm SL, 109 mm SL; Iraq: Choman River.

FIGURE 33. Glyptothorax daemon, paratypes, from left: FSJF 3962, 77 mm SL, 84 mm SL, 101 mm SL, 109 mm SL; Iraq: Choman River.

FIGURE 34. Glyptothorax daemon, FSJF 3962, paratypes; skin ornamentation; from left: 84 mm SL, 101 mm SL, 109 mm SL; Iraq: Choman River.

FIGURE 35. Glyptothorax daemon, paratypes, from top: FFR 3926, 116 mm SL; Turkey: stream Dilektaşı; FSJF 3962, pale form, 78 mm SL; dark form, 110 mm SL; Iraq: Choman River.

FIGURE 36. Glyptothorax daemon, FSJF 3677, 91 mm SL; Turkey: stream Çıratan.