Glyptothorax palakkadiensis Singh and Kosygin, 2025

Glyptothorax palakkadiensis Singh and Kosygin sp. n.

( Figure 1 View Figure 1 )

Type material

Holotype. ZSI FF 8976, 88.2 mm SL; India: Kerala: Palakkad District: Karappara River, Chalakudy River drainage, Parambikulam , 10.4083°N, 76.7214°E, 26 March 1997, collected by K.C. Gopi and Party. GoogleMaps

Paratypes. ZSI FF 8977, 2 ex . GoogleMaps 72.9–92.7 mm SL, same data as holotype.

Diagnosis

Glyptothorax palakkadiensis is distinguished from congeners in the Indian subcontinent in possessing the following combination of characters: the presence of numerous oblique branches of the laterosensory canal that are visible as cream-yellow, spine-like structures radiating irregularly above and below the lateral line; skin ridges present over the entire thoracic adhesive apparatus, including depressed region;the presence of plicae on the ventral surfaces of the pectoral spine and first pelvic-fin ray;body depth at dorsal-fin origin 14.4–16.2% SL; head length 21.8–22.4% SL; caudal-peduncle depth 7.6–8.2% SL; 10 branched pectoral fin rays; and tuberculated fins.

Description

Morphometric data are presented in Table 1. Body elongate ( Figure 1 View Figure 1 ). Head depressed with almost rounded snout when viewed dorsally and ventrally.Dorsal profile rising evenly from tip of snout to origin of dorsal fin, then sloping gently from there to end of caudal peduncle with slight rise at adipose-fin origin. Occipital process not in contact with anterior nuchal plate element. Anterior nuchal plate element W-shaped when viewed dorsally. Ventral profile flat from tip of snout to origin of anal-fin base, then slighty rising to caudal-fin base. Caudal peduncle shallow.Mouth inferior,lips papillate,teeth on upper jaw as one continuous band,its anterior margin almost rounded; teeth on lower jaw separated by a wide partition into two patches. Eyes small, slightly oval, located on dorsal surface of head. Thoracic adhesive apparatus oblong,longer than broad,extending from isthmus to beyond posterior pectoral-fin base with poorly developed median depression on the posterior half, and skin ridges present over entire apparatus,including depressed region,closed caudally,ridges of the apparatus not reaching the gular region ( Figure 2 View Figure 2 ). Anus and urogenital opening located before tip of adpressed pelvic fin. Skin on head and body thickly tuberculated. Lateral line complete, midlateral, laterosensory pores frequently with branches of laterosensory canal system visibly radiating obliquely from it. First branchial arch with 2 + 8(2) or 2 + 9(1) gill rakers. Vertebrae 19 + 18 = 37(3).

Barbels in four pairs. Maxillary barbel long, slender, reaching middle of pectoral-fin base. Outer mandibular barbel longer than inner, almost reaching gill opening. Nasal barbel short, just reaching one-third the distance between origin of nasal barbel and anterior margin of orbit when adpressed.

Dorsal fin with i,6 (3) rays, origin located almost equidistant between adipose-fin origin and snout tip, its spine strong, with anterior margin smooth, posterior margin serrated with 5–6 serrae. Adipose fin low; its origin slightly posterior to anal-fin origin vertically, with anterior margin straight and posterior margin deeply incised with the dorsoposterior margin not angular. Pectoral fin with i, 10(3), its posterior margin almost straight or slightly concave. Pectoral-fin spine broad, long; its anterior margin smooth, posterior margin with 14–17 serrae. Pelvic fin with i, 5½(3) rays, its tip almost reaching anal-fin origin when adpressed. Ventral surface of pectoral-fin spine ( Figure 2 View Figure 2 ) and first pelvic-fin ray plaited. Anal fin long, with ii, 8½(3) rays; its origin anterior to adipose fin origin. Caudal fin deeply forked, lower lobe slightly longer, with 9 + 8 (2) or 8 + 9(1) rays. All fins tuberculated, with numerous minute tubercles along fin rays.

Colour

In 70% alcohol: The dorsal surface of the head and body is dark brown. The lateral surface of the body fades to cream-yellow ventrally. Laterosensory pores along lateral line rimmed in beige tubercles, imparting appearance of a narrow pale cream-yellow line; branches of canals visible as oblique cream-yellow, spine-like structures radiating irregularly above and below lateral line ( Figure 3 View Figure 3 ). Anterior nuchal plate element visible as faint cream-coloured W-shaped extensions. Dorsal, anal, pectoral, pelvic and caudal fins are dusky. The adipose fin is dark brown with a cream-coloured posterior margin.

Distribution

The species is presently known only from the type locality, the Karappara River at Muthuvarachal , Parambikulam , Palakkad District, Kerala, South India ( Figure 4 View Figure 4 ) .

Etymology

The species is named after the Palakkad District of Kerala, India, where the type specimens were collected .