Glyptothorax sardashtensis, Jokar & Kamangar & Ghaderi & Freyhof, 2023

Jokar, Milad, Kamangar, Barzan Bahrami, Ghaderi, Edris & Freyhof, Jörg, 2023, Glyptothorax sardashtensis, a new species of torrent catfish from the upper Lesser Zab drainage in Iran (Teleostei: Sisoridae), Zootaxa 5254 (4), pp. 476-492 : 482-490

Glyptothorax sardashtensis , new species

( Fig. 6–10 )

Holotype: FCFUK 300 , 60 mm SL; Iran: West Azerbaijan prov.: Lesser Zab at bridge east of Nalas , 36.2688 45.5012.

Paratypes: FCFUK 302 , 1 , 51 mm SL; FCFUK 303 , 1 , 42 mm SL; FCFUK 309 , 1 , 41 mm SL; FCFUK 310 , 1 , 40 mm SL; FCFUK 311 , 1 , 38 mm SL; FCFUK 312 , 1 , 38 mm SL; FCFUK 313 , 1 , 37 mm SL; FSJF 4112 , 2 , 51–52 mm; data same as holotype.— FCFUK 304 , 1 , 67 mm SL; FCFUK 305 , 1 , 55 mm SL; Iran: West Azerbaijan prov.: Lesser Zab at Nisk-Abad (now dawned in a reservoir), 36.1369 45.5510 .

Material used for osteology: FCFUK 301 , 58 mm SL ; FCFUK 314 , 38 mm SL ; FCFUK 320 , 31 mm SL; data same as holotype .

Material used for molecular analysis: FCFUK 304 , 67 mm SL (GenBank accession number: OQ078869 ) .— FCFUK 305 , 55 mm SL (GenBank accession number: OQ078870 ); same data as holotype .

Diagnosis: In the Iranian upper Lesser Zab drainage, G. sardashtensis occurs in sympatry with G. kurdistanicus . It is distinguished from this species by having a plain flank, without spots or blotches, with few, very small, darkbrown dots on the head, the dorsal- and adipose-fin bases, and on the caudal-peduncle (vs. flank with many, often large, black spots and blotches) ( Fig. 10 ), three yellowish blotches, arranged in crescent-shaped arch in front of the dorsal-fin origin (vs. arranged in a triangle), a wide medial pit with a roundish anterior margin (vs. narrow with pointed anterior margin in juveniles smaller than 80 mm SL), and the caudal-peduncle depth 1.6–2.3 times its length (vs. (1.2) 1.3–1.7).

Glyptothorax cous and G. steindachneri are two additional species found in the Iraqi part of the Lesser Zab drainage by Freyhof et al. (2021). Glyptothorax sardashtensis is distinguished from G. cous by lacking tubercles on the head and body (vs. having many large, bony, striated, and elongated tubercles). In G. sardashtensis , only few, soft, small warts are present around the thoracic apparatus, on the edges of the gill cover, and on the skin of the dorsal surface of the unbranched pectoral-fin ray. The new species is distinguished from G. steindachneri by having a shorter adipose-fin (12–23% SL vs. 23–30% SL), the medial pit of the thoracic adhesive apparatus without striae (vs. with striae), and the head and body without tubercles (vs. many large, elongated, bony and striated tubercles).

Applying the identification key by Freyhof et al. (2021), G. sardashtensis keys out as G. silviae , by lacking tubercles and warts on the head and anterior body (vs. present in G. armeniacus and G. daemon ) and having few and short anteromedial striae (vs. numerous and long in G. armeniacus and G. daemon ). Furthermore, G. sardashtensis always has a central yellowish blotch on the nuchal plate in front of the dorsal-fin origin (vs. usually absent in G. armeniacus ). Glyptothorax sardashtensis is further distinguished from G. daemon and G. armeniacus by having the thoracic adhesive apparatus slightly elevated (vs. strongly elevated), extending from the isthmus to the base of the third pectoral-fin ray (vs. to the posterior limit of the pectoral-fin base).

Applying the key published by Mousavi-Sabet et al. (2021), G. sardashtensis keys out as G. pallens , G. silviae , G. alidaeii or G. shapuri . Similar to G. pallens , from the adjacent Sirvan drainage, the new species lack dark-brown or black spots and blotches on the flank. Glyptothorax sardashtensis is distinguished from G. pallens by having a shorter outer mandibular barbel (extending to posterior edge of gill cover, not reaching pectoral-fin origin vs. reaching to second pectoral-fin ray), few soft and small warts around the thoracic apparatus, the edges of the gill cover, and the dorsal surface the first unbranched pectoral-fin (vs. many small shallow warts on the head, body, and belly); a thoracic adhesive apparatus slightly elevated (vs. strongly elevated), the medial pit much broader, and its anterior end roundish (vs. narrow and spear-blade shaped), and a more slender caudal peduncle (caudal peduncle depth 1.6–2.3 times in its length vs. 1.1–1.3).

Glyptothorax sardashtensis is distinguished from G. hosseinpanahii by having few and short anteromedial striae (vs. numerous and long). Glyptothorax sardashtensis is distinguished from G. alidaeii , G. hosseinpanahii , G. galaxias , G. shapuri , and G. silviae by having the thoracic adhesive apparatus slightly elevated (vs. strongly elevated), the thoracic adhesive apparatus extending from the isthmus to the level of the base of the third pectoralfin ray (vs. to the posterior-most pectoral-fin base), a wide medial pit (vs. narrow) with a roundish anterior end (vs. pointed), a plain flank, with few, very small, dark-brown dots on the head, the dorsal-, and adipose-fin bases, and on the caudal-peduncle (vs. flank usually with many, rarely few, black spots and blotches, with many additional, greenish-silvery blotches in life, faded in few preserved individuals), and three yellowish blotches on the nuchal plate, arranged in crescent-shaped arch (vs. arranged in a triangle).

Description. See Figures 6–10 for general appearance. Morphometric data in Table 3 . Body subcylindrical. Head depressed, blunt and spade-shaped with a rounded snout margin. Maximum head width 1.6–2.3 times in head depth at eye. Dorsal head profile straight or slightly convex. Predorsal profile slightly convex, then almost straight until adipose-fin origin, sloping gently ventrally at adipose-fin base, almost straight to end of caudal peduncle. Ventral profile straight to anal-fin origin. A shallow keel between base of last dorsal-fin ray and adipose-fin origin. Nuchal plate small ( Fig. 5 ). Caudal-peduncle depth 1.6–2.3 times in its length. Body depth at dorsal-fin origin 1.3– 1.9 times in caudal-peduncle depth. Anus covered by tip of adpressed pelvic fin ( Figs. 7–8 ). Skin of head, back, and flanks without tubercles. Few, soft, small warts around thoracic adhesive apparatus, medial pit, edges of gill cover, and dorsal surface of first unbranched pectoral-fin ray. Snout 1.5–2.0 times longer than interorbital distance. Lateral line complete. Eye ovoid, horizontal axis longest. Dorsal-fin origin situated closer to adipose-fin origin than to tip of snout. Predorsal length 1.1–1.3 times in distance between dorsal-fin origin and adipose-fin origin. Posterior dorsalfin margin straight or slightly convex. Last unbranched dorsal-fin ray 11–15% SL; without serrations, distal 20% of its length soft, poorly ossified. First branched dorsal-fin ray longest, its length 13–18% SL. Anterior adipose-fin margin straight or slightly convex, posterior margin round. Adipose-fin origin above or very slightly in front of vertical of anal-fin origin. Caudal fin forked with rounded lobes, lower lobe slightly wider than upper lobe. Anterior anal-fin margin straight or slightly convex, posterior margin straight to slightly concave. Pelvic-fin origin below or slightly behind vertical of dorsal-fin origin. Its anterior margin slightly convex. Pelvic fin reaching anal-fin origin, its length 1.1–1.6 times longer in distance between pelvic-fin origin and anus. Distance between anus and anal-fin origin 4.7–6.8% SL. Pectoral fin reaching vertical of base of last branched dorsal-fin ray, its length 0.7–1.0 times in distance between pectoral and pelvic-fin origins. Posterior-fin margin slightly concave, anterior margin smooth, posterior margin with 9–11 serrations; distal 25% of ray soft without serrae ( Fig. 11 ).

Dorsal fin with two visible unbranched rays and 5½ (n=18) branched rays. Caudal fin with ii,7+7,ii (10), ii,8+7,ii (5), i,7+7,ii (1), i,8+8,i (1), ii,9+9,ii (1) principal rays. Anal fin with one unbranched and 5½ (10), 6½ (8) branched fin rays. Pelvic fin with one unbranched and 5 (18) branched rays. Pectoral fin with one unbranched and 7 (11), 8 (7) branched fin rays.

Thoracic adhesive apparatus with striae or narrow longitudinal pleats located in a rhombic field extending from isthmus to base of second branched pectoral-fin ray ( Fig. 7–8 ). Anteromedial striae few and short ( Fig. 12 ). Medial pit wide, without striae, its anterior end roundish. Thoracic adhesive apparatus’s anterolateral edges almost straight or slightly concave, its length is 0.8–1.2 times its width. Barbels in four pairs. Maxillary barbel broad and thick, reaching almost to pectoral-fin base, to fourth or fifth dorsal-fin ray in some individuals. Inner mandibular barbel reaching to isthmus. Outer mandibular barbel reaching to posterior edge of gill cover, not reaching pectoralfin origin. Nasal barbel reaching almost to anterior eye margin. Mouth inferior, when closed, exposing a crescentshaped band of premaxillary teeth. Anterior and posterior nares closely spaced and separated only by base of nasal barbel. Anterior nasal circular, posterior triangular with two external flaps.

Osteology. Premaxillary tooth plate crescent shaped consisting of four bony elements. One pair of proximal elements located medially and one pair of distal elements located laterally, all of which are connected by connective tissue ( Fig. 5B ). Proximal bones pentagonal in shape, distal elements rod-shaped with straight anterior margins. Proximal element with straight inner margin, medially attached to opposite proximal element.Anterior and posterior margins straight, their outer side with anterolateral and posterolateral margins. Anterolateral margin of proximal element located at an angle with anterior margin of distal element. Premaxillary tooth plate ventrally with numerous villiform teeth in several rows, their tips slightly turned backward. Nuchal plate covered by thin skin. Anterior and middle elements, small triangular ( Fig. 5D ). Anterolateral margins concave or slightly straight, forming a pointed tip in medial anterior. Medial anterior tip short reaching horizontally to level of rib of seventh vertebra. Tip is not turned upward. Posterior margin concave and its posterolateral tip turned back widely contacting posterior element. Posterior element expands horizontally, trapezoid in shape. Dentary consists of two halves connected by connective tissue at midline forming a single crescentic band ( Fig. 5F ). Anterior portion of dentary more slender than its posterior part. Anterior portion with several rows of long, villiform teeth. Vomer edentulous, consisting of a large, triangular plate anteriorly, and a long stem posteriorly ( Fig. 5H ). Vomer’s triangular plate concave in its anterolateral and posterior margins, resulting in a thin lateral process and a sharply pointed medial anterior tip.

Coloration. In 70% ethanol: background colour of head and body brown, ventral surface yellowish-brown, thoracic adhesive apparatus yellowish to pale-grey. Body immaculate, some individuals with few, minute dots, darker than background coloration around head, dorsal-fin base, adipose-fin base, and caudal-peduncle.An upper and lower yellowish blotch at posteriormost caudal peduncle. Three pale-grey blotches, organised in a crescent-shaped arch in front of dorsal-fin origin, fused in some individuals. A yellow blotch at and on back behind posteriormost dorsal-fin base, faded in most individuals. Dorsal fin with a brown base and last unbranched dorsal-fin ray brown. Dorsal-fin membranes hyaline or yellowish, rays brown or yellowish, usually brown in middle of ray and yellowish at tip. Adipose fin with a large, elongate, yellowish blotch at origin and a small yellowish blotch at posterior margin. Caudal fin dark-brown, with a blackish base, followed by a yellowish band, usually reduced into two yellowish blotches, and yellowish caudal-fin tips. All other fins yellowish with a brown base, a central, wide, brown band, often reduced to brown fin-rays. Maxillary and nasal barbels grey or blackish dorsally, pale-grey ventrally and velum pale-grey or beige. Mandibular barbels beige or pale-grey.

In life: colour pattern identical to preserved individuals, background colour of head and body olive-green. Pattern on body and fins yellow.

Distribution. Upper reaches of the Lesser Zab drainage. So far it was found at two places only. Following the construction of the Sardasht Dam and the impound of its reservoir in 2017, one place became submerged. In June 2017, G. sardashtensis could only be found near Nalas village.

Etymology. Named for the Sardasht County, where the species is found. This is also in the memorial of the victims of the chemical attack in the area on 28 June 1987. An adjective.

Habitat. Glyptothorax sardashtensis was found in habitats with fast water velocity, shallow waters, and predominantly pebbles to cobbles substrate.

Remarks. Sayyadzadeh et al. (2022) treat G. alidaeii , G. hosseinpanahii , G. galaxias , and G. shapuri as synonyms of G. silviae , and propose these species to be indistinguishable by external characters. Interestingly, Eagderi et al. (2022), published after Sayyadzadeh et al. (2022), partly with an overlapping team of co-authors, treat these species as valid. This is not the place to discuss this opinion and the morphological characters in detail. All Glyptothorax species of the Persian Gulf basin are superficially similar; even species found in sympatry largely overlap in their morphometric characters as already demonstrated by Freyhof et al. (2021). The absence of morphometric characters, as found by Sayyadzadeh et al. (2022), can therefore not prove that all these species are conspecific.

To our surprise, Sayyadzadeh et al. (2022) found the molecular lineages identified as G. galaxias and G. alidaeii in sympatry, clearly counteracting their conclusion, that these two species are conspecific. Naturally, we are aware, that two mitochondrial lineages might be found in one species following introgressive hybridisation. This needs to be tested in the future. Until then, we see no other way than to treat G. galaxias as a valid species as sympatry strongly suggest also reproductive isolation in sympatry, one of the strongest indications for the fact, that two species have to be recognised. Mousavi-Sabet et al. (2021), Sayyadzadeh et al. (2022), and Table 2 in this study, given the K2P distances between the different species. In all these tables, the K2P distance between G. galaxias and G. alidaeii is clearly below 2%, a situation that needs some additional research as it might shed some light also in the validity of the allopatric species.

Other than morphometric characters have not been analysed in detail by Sayyadzadeh et al. (2022) and should be the objective of future studies, before G. alidaeii , G. hosseinpanahii , and G. shapuri are accepted as synonyms of G. silviae . Morphometric characters seem to be rather conservative in Glyptothorax from Western Asia and we also found no differences in morphometrics between G. sardashtensis and sympatric G. kurdistanicus ( Table 3 ). We agree with Sayyadzadeh et al. (2022) that G. alidaeii , G. hosseinpanahii , G. shapuri , and G. silviae form four welldifferentiated, but closely related molecular groups, which should, in the absence of morphological differences, be all treated as conspecific. This case is similar to the Oxynoemacheilus bergianus (Nemacheilidae) species group discussed by Freyhof et al. (2022), who treat several molecular clusters as conspecific and discuss such cases and the rationals behind this conclusion, in detail. In contrast, Esmaeili et al. (2014) distinguish several molecular clusters of the Esmaeilius sophiae (Aphaniidae) group as different species. Esmaeili et al. (2020) describe a new species of Rhodeus (Acheilgnathidae) , and Khaefi et al. (2017) distinguish different molecular clusters of the Barbus lacerta (Cyprinidae) group as species, without morphological differences demonstrated.

The diagnostic value of osteological characters has not been assessed in Glyptothorax species from the Persian Gulf basin. Gauba (1966), Vishwanath et al. (2010), and Jiang (2012) studied such characters in East Asian species of the genus. Our dataset is for sure too limited to use osteological characters to distinguish G. sardashtensis and more materials of more species should be studied. We compared few individuals of G. sardashtensis with few G. kurdistanicus and found the premaxillary tooth plate in G. sardashtensis having a pair of rod-shaped distal elements with straight anterior margins (vs. wedge-shaped, with convex anterior margins in G. kurdistanicus ). The anterior side of the triangular-shaped nuchal plate is less stretched reaching horizontally to the level of the seventh vertebra (vs. the sixth vertebra in G. kurdistanicus ). Its anterior tip is not turned up (vs. turned up in G. kurdistanicus ), causing the three blotches in the front of the dorsal fin to look like a crescent shaped arch (vs. triangular in G. kurdistanicus ). The posterior margin of the vomer’s triangular plate is concave, (vs. straight in G. kurdistanicus ).

As G. sardashtensis occurs in sympatry with G. kurdistanicus , it is worthwhile to discuss, which of the two species is the one described by Berg (1931) as G. kurdistanicus . Glyptothorax sardashtensis is distinguished from G. kurdistanicus by having a plain flank, with few, minute, dark-brown spots on the head, the dorsal-, and adiposefin bases, and on the caudal-peduncle in some individuals (vs. flank with many, large, black spots and blotches in G. kurdistanicus ). Freyhof et al. (2021) show the type of G. kurdistanicus (ZIN 20780) and the figures drawn from the type published by Berg (1931). The type has indeed few, large black spots on the flank. Not as prominent as in individuals shown by Freyhof et al. (2021) and in our study ( Fig. 2 ), but much larger than in G. sardashtensis . In none of the individuals of G. sardashtensis , such spots on the flank are found. The caudal-peduncle depth in G. sardashtensis is 1.6–2.3 times its length (vs. 1.3–1.7 in G. kurdistanicus ). Berg (1931) give the depth of the caudal peduncle as 81% of its length. This corresponds to a caudal-peduncle depth 1.2 times its length, making it also likely that our identification of G. kurdistanicus is correct. ZIN 20780 has a short thoracic adhesive apparatus and this character state has also been found in other fishes identified as G. kurdistanicus by Coad (1981, 2010) and Freyhof et al. (2021). Also this character indicates that our identifications are correct. Berg (1931) figure the medial pit of ZIN 20780 with a roundish anterior tip but its shape is difficult to see in the partly destroyed, thoracic adhesive apparatus of ZIN 20780 shown by Freyhof et al. (2021). ZIN 20780 is 113 mm SL and other individuals of G. kurdistanicus in the same size category shown in Fig. 22 by Freyhof et al. (2021), also have a roundish anterior tip of the medial pit. This character state was not found in G. kurdistanicus collected from Iran ( Fig. 12 ), except for one large individual (108 mm SL, Fig. 3 ). As juvenile individuals of G. kurdistanicus shown by Freyhof et al. (2021: Fig. 21) have a pointed anterior tip of the medial tip, this character might be variable depending on size, pointed in small, roundish in large individuals. In G. sardashtensis , however, we found no size-dependent variability of this character. As both, G. sardashtensis and large G. kurdistanicus have a median pit with a roundish anterior tip, this character does not allow to distinguish larger individuals (as in ZIN 20780) of both species. Also, the skin on the nuchal plate in ZIN 20780 is destroyed, and the shape of the yellowish blotch on that plate cannot be seen. As a conclusion, we remain confident to have identified the right fishes as G. kurdistanicus based on the very deep caudal peduncle, the colour pattern, and the shape of the thoracic adhesive apparatus.

Comparative material. Materials listed by Freyhof et al. (2021) was also used for this study. Additional comparative materials are:

Glyptothorax alidaeii: FSJF 4111, 2, 35–78 mm SL; Iran: Lorestan prov.: Seimare at Zirkhaki , 33.6880 47.0639 .

Glyptothorax galaxias: FCFUK 344, 1, 59 mm SL; FCFUK 345 , 1 , 80 mm SL ; FCFUK 350 , 1 , 95 mm SL ; FCFUK 351 , 10 , 62–104 mm SL; Iran: Lorestan prov.: Kashkan at Kaka-Reza , 33.7856 48.2064 .— FSJF 4112 , 2 , 47– 52mm SL; Iran: Chaharmahal-va-Bakhtiari prov.: stream Beheshtabad at Beheshtabad , 32.0287 50.6265 .— FSJF 2214 , 1 , 57 mm SL; Iran: Sangan at Sangan , 31.2587 51.2858 .— FSJF 3243 , 24 , 31–48 mm SL; Iran: Beshar at Doruhan , 30.8521 51.3420 .

Glyptothorax hosseinpanahii: FSJF 4113, 1, 36 mm SL; Iran: Khuzestan prov.: Zohreh River at Kheirabad , 30.5295 50.4156 .

Glyptothorax pallens: FCFUK 371, 1, 48 mm SL; FCFUK 372 , 1 , 59 mm SL; FCFUK 373 , 1 , 62 mm SL; Iran: Kermanshah prov.: stream Zemkan north of Zamkan-e Olya , 34.6416 46.2841.— FSJF 4114 , 1 , 65 mm SL; Iran: Kermanshah prov.: stream Zemkan 3 km north of Zamkan-e Olya , 34.6452 46.2856 .

Glyptothorax shapuri: FSJF 4115, 1, 57 mm SL; Iran: Fars prov.: Shapur River at Eslamabad , 29.7618 51.5507 .

Glyptothorax silviae: FSJF 4116, 5, 45–95 mm SL; Iran: Kohgiluyeh-va-Boyer Ahmad prov. : Maroun River at Garab-e-Lodab, 30.9455 50.9042 .

Figures

FIGURE 2. Glyptothorax kurdistanicus, FCFUK 330, 108 mm SL; upper Lesser Zab, Iran.

FIGURE 3. Glyptothorax kurdistanicus, from left: FCFUK 330, 108 mm SL; FCFUK 333, 52 mm; SL; Lesser Zab, Iran.

FIGURE 5. Premaxillary tooth plate, nuchal plate, dentary elements, and vomer plate of G. kurdistanicus (A, C, E, and G respectively), FCFUK 338, 41 mm SL, and G. sardashtensis (B, D, F, and H respectively), FCFUK 314, 38 mm SL; a and b, ventral view of premaxillary tooth plate; c and d, dorsal view of the nuchal plate; e and f, dorsal view of dentary elements; g and h, ventral view of vomer plate. Abbreviations: ppe, premaxillary proximal element; pde, premaxillary distal element; anp, anterior nuchal plate; mnp, middle nuchal plate; pnp, posterior nuchal plate; spl, spinlet; fdr, first dorsal-fin ray; vt, villiform teeth; vp, vomerine plate; ps, posterior stem.

FIGURE 6. Glyptothorax sardashtensis, FCFUK 300, holotype, 60 mm SL; Lesser Zab, Iran.

FIGURE 7. Glyptothorax sardashtensis, FCFUK 300, holotype, 60 mm SL; Lesser Zab, Iran.

FIGURE 8. Glyptothorax sardashtensis, paratypes, from left: FCFUK 302, 51 mm SL; FCFUK 303, paratype, 42 mm SL. Lesser Zab, Iran.

FIGURE 9. Glyptothorax sardashtensis, from left: FCFUK 300, holotype, 60 mm SL; FCFUK 302, paratype, 51 mm SL; FCFUK 305, paratype, 55 mm SL; Lesser Zab, Iran.

FIGURE 10. Comparison of the presence or absence of spots and blotches inG.sardashtensis and G. kurdistanicus. Glyptothorax sardashtensis, from left: FCFUK 306, 51 mm SL; FCFUK 321, 45 mm SL; Lesser Zab, Iran. Glyptothorax kurdistanicus, from right: FCFUK 332, 67 mm SL; FCFUK 337, 43 mm SL; Lesser Zab, Iran.

FIGURE 11. Pectoral-fin spine of Glyptothorax sardashtensis. From left to right FCFUK 320, 31 mm SL, FCFUK 314, 38 mm SL, and FCFUK 301, 58 mm SL. Numbers indicate the number posterior serrae, pink is the ossified part.

FIGURE 12. Glyptothorax kurdistanicus, upper row, from left: FCFUK 339, 27 mm SL; FCFUK 337, 43 mm SL; FCFUK 332, 67 mm SL; G. sardashtensis, lower row, from left: FCFUK 322, 21 mm SL; FSJF 4112, 52 mm SL; FCFUK 305, 55 mm SL; Lesser Zab, Iran.