Glyptothorax kurdistanicus ( Berg, 1931 )

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 : 472-477

Glyptothorax kurdistanicus ( Berg, 1931)

( Fig. 18–24 )

Glyptosternum kurdistanicum Berg, 1931:1267

Material examined. ZIN 20780, 113 mm SL; Iran: Kurdistan, at the village Germau (or Germav ).— FSJF 3652 , 4 , 49–77 mm SL; Iraq: Aw-e Shiler at Khewata, 35.7509 45.4797 (photographs only).— FFR 3906 , 2 , 75–122 mm SL; FFR 3924, 1, 104 mm SL; Bitlis prov.: stream Çıratan 3 km southwest of Üçadım , 38.3547 41.7814.— FFR 3916 , 5 , 84–120 mm SL; Hakkari prov.: stream Eziki 6 km northeast Konak, 37.6717 43.8628.— FFR 3910 , 1 , 76 mm SL; Turkey: Diyarbakır prov.: stream Kara 11 km northwest of Lice, Tigris drainage, 38.5294 40.5455.— FFR 3921 , 2 , 64–78 mm SL; Turkey: Bitlis prov.: stream Oraniz at Ekinli , 38.1386 42.4303.— FFR 3923 , 1 , 70 mm SL; Turkey: Siirt prov.: stream Kezer at Köprübaşı , 37.9558 41.8561.— FFR 3929 , 1 , 63 mm SL; Turkey: Şırnak prov.: stream Ortasu at Bağlıca , 37.4411 42.7483.— NMW 90584 , 1, 127 mm SL; Turkey: Botan River (photographs only).

Material used in molecular genetic analysis. FSJF-DNA 2647; Iraq: Aw-e Shiler at Khewata , 35.7509 45.4797 (GenBank accession numbers: MW770717, MW770720, MW770728 ) .— FSJF-DNA 3335; Turkey: Bitlis prov.: stream Çıratan 3 km southwest of Üçadım , 38.3547 41.7814 (GenBank accession numbers: MW724522, MW724523, MW724524 ) .— FSJF-DNA 3349; Iraq: Qal’ah Chwalan River at Bardbard , 35.9150 45.36772 (GenBank accession number: MW724521 ) .

Diagnosis. Glyptothorax kurdistanicus is distinguished from its congeners in the Euphrates and Tigris drainages by having the thoracic adhesive apparatus 0.7–0.9 (1.0 in juveniles) times longer than wide (vs. 1.0– 1.5 in G. armeniacus , 0.8–1.1 in G. cous ), extending from the isthmus to the base of the first or third branched pectoral-fin ray (vs. to or beyond last pectoral-fin ray). It is further distinguished from G. armeniacus and G. cous by having no or few very short anteromedial striae (vs. numerous and well developed), many small, often elongated warts on the dorsal and lateral head, back and flank (vs. with large, bony, striated and elongated tubercles in G. cous ; with small tubercles and few warts in G. armeniacus ), an elevated thoracic adhesive apparatus (vs. not elevated in G. cous ), well delineated at its posterior margin (poorly delineated in G. cous ); completely situated on a horse-shoe shaped swelling (vs. reaching beyond swelling, usually onto the pectoral-fin base in G. cous ), and the caudal-peduncle depth 1.1–1.6 times in its length (vs. 1.6–2.3 in G. cous ). See below for characters to distinguish this species from other Glyptothorax in the Middle East.

Other characters useful for identification are: medial pit without striae; adipose-fin short, its length 0.6–1.0 times larger than the distance between the base of last dorsal-fin ray and adipose-fin origin; head blunt, spade-shaped, 27–30% SL; few black or dark-brown blotches on flank. Size up to 127 mm SL.

Distribution. Glyptothorax kurdistanicus seems to be endemic to the Tigris drainage where it has been found in mountain rivers in Turkey, Iran and Iraq down to the Lesser Zab drainage.

Remarks. When Berg (1931) described G. kurdistanicus from the Lesser Zab, he was not aware of the existence of G. cous and therefore did not distinguish G. kurdistanicus from G. cous . We found two molecular clades in the Lesser Zab, one of them, we identify as G. cous and the second as G. kurdistanicus . The type of G. kurdistanicus (ZIN 20780, Fig. 18 ) is not in a good condition, parts of the skin and the thoracic adhesive apparatus are lost, fins are broken, and the head is turned down. However, the diagnostic deep caudal peduncle and the short thoracic adhesive apparatus are well visible in the type. The thoracic adhesive apparatus extends from the isthmus to the base of the first or third branched pectoral-fin ray in ZIN 20780 as well as in our material of G. kurdistanicus . In G. cous , the thoracic adhesive apparatus is extending from the isthmus to the base of the last pectoral-fin ray or to the posterior limit of the pectoral-fin base. Furthermore, the apparatus is elevated in G. kurdistanicus (vs. not in G. cous ).

We do not see the bony, striated, elongated tubercles on the head, back and flank diagnostic for G. cous . As these tubercles are very peculiar, we would expect Berg (1931) to mention them, what he did not. Mikhail Nazarkin (ZIN) examined the specimen and did not find tubercles on ZIN 20780 (pers. comm., 2020). While the tubercles might all have been scraped off in ZIN 20780, they also might have never existed, as in the other materials from the Lesser Zab examined by us. Indeed, the sole adult G. kurdistanicus collected from the Lesser Zab ( Fig. 24 ) agrees very well with the type in the general body shape also supporting our identification of this species as G. kurdistanicus .

It is unclear, in which condition ZIN 20780 was, when Berg studied it. On the drawing, the head was already turned downwards, the pattern of black dots on the flank agrees well in the type and its drawing and Berg (1931) does not give the number of serrae on the inner margin of the ossified pectoral fin-ray. In ZIN 20780, the ossified ray is broken today. To us, it seems possible that ZIN 20780 was already in a poor condition when Berg (1931) examined it but we are unable to demonstrate this. Potentially, he took some artistic freedom when preparing the drawing of ZIN 20780, resulting in complete fins, and a complete thoracic adhesive apparatus, which is incomplete in ZIN 20780.

Berg (1931) distinguish G. kurdistanicus from G. armeniacus , described by him in 1918, by the thoracic adhesive apparatus wider than long in G. kurdistanicus (vs. longer than wide in G. armeniacus ), a character adopted by later authors ( Kuru 1975, Geldiay & Balık 1999, Kaya et al. 2016). Coad (1981) diagnosed G. kurdistanicus by having the thoracic adhesive apparatus wider than long or as wide as long. However, materials identified as G. kurdistanicus by Coad (1981) originate from the Turkish Euphrates (ZMH 4430) and not from the Iranian Lesser Zab or even from the Tigris drainage, from where G. kurdistanicus was described. The two individuals (ZMH 4430) identified by Coad (1981) as G. kurdistanicus were identified by us as G. cous , and most materials identified as G. cous from SMF was previously identified as G. kurdistanicus . Indeed, in G. kurdistanicus and G. cous the thoracic adhesive apparatus might be as wide as long and therefore these species are confused in the literature. The apparatus is reaching only to the base of the first or third branched pectoral-fin ray in G. kurdistanicus , a character state clearly different from G. cous .

Except of the short thoracic adhesive apparatus, Berg (1931) distinguished G. kurdistanicus from G. armeniacus by the thoracic adhesive apparatus lacking pinnate striae (vs. present). In our material of G. kurdistanicus , pinnate striae occur while not as many as in G. armeniacus . Berg (1931, Fig. 1 ) shows that G. kurdistanicus also lacks anteromedial striae on the thoracic adhesive apparatus. However, no pinnate or anteromedial striae can be seen. Our materials show few and short anteromedial striae, much less than in G. armeniacus .

Berg (1931) gives the type locality „in Kurdistan, at the village Germau (or Germav), at the height of 1500 m ... Germau (or Germav, Germaw) is situated in latitude 36°N southeast of Serdesht, on the western slope of the Sur-kei Range, in the basin of the river Bané, tributary to the Lesser Zab, which is tributary to the Tigris R.“. Coad (2014) stated that Germau is probably Garmab and Bané is probably Baneh. The village of Germab could not be located in gazetteers or on maps with a relevant longitude but Sar Dasht (36°09‘N, 45°28‘E) and Baneh (35°59‘N, 45°53‘E) are evident and the locality is between them and lies in the Iranian Lesser Zab drainage. We are not aware that any Glyptothorax has been recorded from the Iranian Lesser Zab and Esmaeili (pers. comm., 2012) was not aware of a recent record of the species.

The distribution of G. kurdistanicus remains largely unclear and it could be endemic to the Tigris drainage from headwaters in Turkey down to the Lesser Zab, in Iraqi Kurdistan and Iran. Jouladeh-Roudbar et al. (2020) show one Glyptothorax from the Sirvan identified as G. kurdistanicus , but this fish is quite different from those found in the Lesser Zab and resembles G. silviae from its general appearance.

We found G. kurdistanicus and G. cous sympatric in the Aw-e Shiler River which is a tributary of the Lesser Zab and G. steindachneri is a third species also recorded from the Lesser Zab drainage. Glyptothorax cous and G. steindachneri are widespread species found in middle-size to large rivers. But G. armeniacus , G. daemon , G. silviae and potentially also G. kurdistanicus are small species, which are highly rheophilic and they seem to inhabit smaller, fast flowing rivers.

Figures

FIGURE 1. Thoracic adhesive apparatus of Glyptothorax, showing structures defined and mentioned in this study: anterolateral striae (ALS); anteromedial striae (AMS); medial pit (MP) (G. daemon, FSJF 3962, 109 mm SL; based on Ng & Kottelat 2016).

FIGURE 18. Glyptothorax kurdistanicus, ZIN 20780, type, 113 mm SL; Iran: Germau (or Germav). Drawings modified from Berg (1931).

FIGURE 19. Glyptothorax kurdistanicus, juveniles, from top: FSJF 3652, top: 77 mm SL, 69 mm SL; Iraq: Aw-e Shiler River.

FIGURE 20. Glyptothorax kurdistanicus, adults, from top: FFR 3916, from top: 120 mm SL, 104 mm SL, 98 mm SL; Turkey: stream Eziki.

FIGURE 21. Glyptothorax kurdistanicus, juveniles, from left: FSJF 3652, from left: 66 mm SL, 69 mm SL, 77 mm SL; Iraq: Aw-e Shiler River.

FIGURE 22. Glyptothorax kurdistanicus, adults, from top: FFR 3916, from left: 120 mm SL, 104 mm SL, 98 mm SL; Turkey: stream Eziki.

FIGURE 23. Glyptothorax kurdistanicus, skin ornamentation; from left: adults, FFR 3916, from left: 120 mm SL, 104 mm SL, 98 mm SL; Turkey: stream Eziki.

FIGURE 24. Glyptothorax kurdistanicus, from top: FSJF 3652, 77 mm SL; Iraq:Aw-e Shiler River; FSJF-DNA 3349; 120 mm SL; Iraq: Qal’ah Chwalan River.