Glyptothorax pallens, Mousavi-Sabet & Eagderi & Vatandoust & Freyhof, 2021

Mousavi-Sabet, Hamed, Eagderi, Soheil, Vatandoust, Saber & Freyhof, Jörg, 2021, Five new species of the sisorid catfish genus Glyptothorax from Iran (Teleostei: Sisoridae), Zootaxa 5067 (4), pp. 451-484 : 472-476

Glyptothorax pallens , new species

( Fig. 19–22 )

Holotype. GUIC GTI-H, 67 mm SL; Iran: Kermanshah prov.: stream Zemkan 3 km north of Zamkan-e Olya , 34.6452 46.2856.

Paratypes. FSJF 4114 , 1 , 65 mm SL ; IMNRF-UT-1227 , 3 , 21–69 mm SL; same data as holotype .— IMNRF-UT-1228 , 1 , 57 mm SL; Iran: Kermanshah prov.: stream Golain at Sare-Baghe-Golain, 34.2280 46.0035 .— IMNRF-UT-1229 , 1 , 50 mm SL; Iran: Kermanshah prov.: stream Alvand near Qasr-e-Shirin , 34.4809 45.7556 .— VMFC GTI-P, 1, 56 mm SL; Iran: Kermanshah prov.: Sirvan River at Hajij (now under Daryan reservoir), 35.1602 46.3391 .

Material used in molecular genetic analysis. IMNRF-UT-1227 ; same data as holotype ( GenBank accession number: MZ959038 , MZ959040 ) .— IMNRF-UT-1228 ; Iran: Kermanshah prov.: stream Golain at Sare-Baghe-Golain , 34.2280 46.0035 (GenBank accession number: MZ959041 ) .— IMNRF-UT-1229 ; Iran: Kermanshah prov.: stream Alvand near Qasr-e-Shirin , 34.4809 45.7556 (GenBank accession number: MZ959042 ) ,— VMFC GTI-11; Iran: Kermanshah prov.: Sirvan River at Hajij , 35.1602 46.3391 (GenBank accession number: MZ959039 ) .

Diagnosis. Glyptothorax pallens is distinguished from its congeners in the Persian Gulf basin by lacking black, brown or silvery-beige spots or blotches on the head, back and flank (vs. with spots and blotches or only spots), and having a longer maxillary barbel (90–95% HL vs. 57–92 in all others congeners with exceptions of G. hosseinpanahii , and G. silviae ). It is further distinguished from G. silviae by having a deeper caudal-peduncle (1.1–1.3 times in its length vs. 1.3–1.6), and shorter mandibular barbels (inner mandibular barbel 38–42% HL vs. 45–48, outer mandibular barbel 52–59% HL vs. 67–74).

The new species is further distinguished from G. alidaeii by having the thoracic adhesive apparatus strongly elevated (vs. moderately elevated), 1.0–1.2 times longer than wide (vs. 1.3–1.6), a blunt and roundish head (HL 25–28% SL vs. pointed, 21–24), a deeply forked caudal fin (shortest middle caudal-fin ray 47–53% of the longest ray of the upper caudal-fin lobe vs. 57–65).

Glyptothorax pallens is further distinguished from G. galaxias by having the thoracic adhesive apparatus 1.0– 1.2 times longer than wide (vs. 1.3–1.5), without or with very short anteromedial striae (vs. many and long), a blunt and roundish (vs. pointed) and long head (HL 25–28% SL vs. 21–23), the caudal-peduncle depth 1.1–1.3 times in its length (vs. 1.6–2.1), pointed caudal fin lobes (vs. rounded), a deeply forked caudal fin (shortest middle caudal-fin ray 47–53% of the longest ray of the upper caudal-fin lobe vs. 61–65).

It is further distinguished from G. hosseinpanahii by having the thoracic adhesive apparatus strongly elevated (vs. moderately elevated), without or with very short anteromedial striae (vs. many and long), and the caudal-peduncle depth 1.1–1.3 times in its length (vs. 1.3–1.6).

Glyptothorax pallens is distinguished from G. shapuri by having a more shallow and slender head (head depth 53–57% HL vs. 58–61, maximum head width 73–80% HL vs. 86–90), longer barbels (maxillary barbel 90–95% HL vs. 81–84, inner mandibular barbel 38–42% HL vs. 18–22, outer mandibular barbel 52–59% HL vs. 42–44), and no distinct spot or blotches on the head, back and flank (vs. few, irregular shaped, dark-brown blotches).

The new species is further distinguished from G. armeniacus and G. daemon by having no or very short anteromedial striae (vs. many and long), the caudal-peduncle depth 1.1–1.3 times in its length (vs. 1.6–2.1), pointed caudal fin lobes (vs. rounded), and a deeply forked caudal fin (shortest middle caudal-fin ray 47–53% of the longest ray of the upper caudal-fin lobe vs. moderately forked, 62–69% in G. armeniacus , 55–59 in G. daemon ).

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 adipose fin to end of caudal peduncle. Ventral profile straight to end of caudal peduncle. Caudal-peduncle depth 1.1–1.3 times in its length. Anus and urogenital openings located below tip of adpressed pelvic fin. Skin of head, body and belly many small shallow warts. 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 warts. Eye ovoid, horizontal axis longest; located just below dorsal-head profile. Largest individual recorded 69 mm SL.

Barbels in four pairs. Maxillary barbel broad and thick, reaching posterior margin of pectoral-fin base, velum at proximal part of babel attached to head closer to posterior nare than to eye, warts on outer base of velum, velum smooth. Nasal barbel broad, extending to anterior orbital margin, reaching mid eyes in some individuals. Inner mandibular-barbel extending to isthmus. Outer mandibular barbel extending to end of gill cover, reaching second pectoral-fin ray. 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 striae in an elongate oblong field extending from isthmus to base of the third branched pectoral-fin ray ( Fig. 21 ); anterolateral edges of adhesive apparatus almost straight or slightly concave; its width 1.0–1.2 times in its length; completely situated on a horse-shoe shaped swelling, without warts at its lateral and posterior edge. Anteromedial striae absent or slightly developed. Spear-blade shaped medial pit on posterior half of thoracic adhesive apparatus. Dorsal fin located above anterior third of body, with 6 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 in front of anal-fin origin. Caudal fin with pointed lobes, lower lobe slightly longer than upper lobe and i,15,i principal rays. Anal-fin base vertically opposite adipose-fin base. Anal fin with slightly convex anterior margin and straight or slightly concave posterior margin; with 6 branched rays. Pelvic-fin origin at vertical slightly in front of or behind tip of adpressed dorsal fin. Pelvic fin with slightly convex anterior margin and I,5 rays; tip of adpressed fin not reaching anal-fin origin. Pectoral fin with I,7–8 rays; posterior fin margin straight; anterior spine margin smooth, with many unculi and a honey-comp pattern on lower surface, inner margin with 10–11 serrae. Back anterior to adipose fin flat or slightly rounded, with a shallow keep in some individuals, expanded distal tips of neural spines not forming a series of bumps.

Coloration. In 70% ethanol: background colour dark- to pale-brown, fading to cream or beige on ventral surfaces of head and anterior belly and on pectoral and pelvic-fin bases. Head, back and flank without black or darkbrown spots or blotches, with many, very small dark-brown points, much smaller than eye diameter. Latero-sensory pores same colour as surrounding tissue. A beige blotch at dorsal and adipose fins origin. Adipose fin dark-brown with a beige posterior margin. All other fins with a dark-brown base, followed by a hyaline or whitish median band, a dark-brown band and a hyaline or whitish margin, often reduced to hyaline or whitish tips in caudal fin. Maxillary and nasal barbels brown or blackish dorsally, pale-brown ventrally and velum pale-brown or beige. Mandibular barbels beige or cream.

In life: head, back and flank greyish brown, fading to beige or whitish on ventral surfaces, with minute black points, much smaller than eye diameter.

Etymology. This species is named for its pale colour, an adjective, indeclinable.

Distribution. Glyptothorax pallens was found in the tributaries of the Sirvan in Iran, including the Sirvan itself and the tributaries Zemkan, Golain and Alvand. As the Sirvan flows to Iraq to meet the Tigris, it is expected that this species also occurs in that country. A noun in genitive, indeclinable.

Figures

FIGURE 19. Glyptothorax pallens, GUIC GTI-H, holotype, 67 mm SL; Iran: stream Zemkan.

FIGURE 20. Glyptothorax pallens, paratypes; from top: IMNRF-UT-1227, 69 mm SL; Iran: stream Zemkan; VMFC GTI-P, 56 mm SL; Iran: Sirvan; IMNRF-UT-1228, 57 mm SL; Iran: stream Golain; IMNRF-UT-1229, 50 mm SL; 51 mm; Iran: stream Alvand.

FIGURE 21. Glyptothorax pallens, thoracic adhesive apparatus, paratypes; from left: IMNRF-UT-1227, 69 mm SL; Iran: stream Zemkan; VMFC GTI-P, 56 mm SL; Iran: Sirvan; IMNRF-UT-1229, 51 mm; Iran: stream Alvand.

FIGURE 22. Glyptothorax pallens, from top: GUIC GTI-H, holotype, 67 mm SL; Iran: stream Zemkan; VMFC GTI-P, paratype, 56 mm SL; Iran: Sirvan.