Chiloglanis asperocutis Mutizwa, Bragança & Chakona, 2025

Mutizwa, Tadiwa I., Bere, Taurai, Kadye, Wilbert T., Bragança, Pedro H. N. & Chakona, Albert, 2025, Description of two new species of Chiloglanis (Teleostei, Mochokidae) from the Eastern Zimbabwe Highlands freshwater ecoregion: an overlooked hotspot of rheophilic fishes, ZooKeys 1241, pp. 261-290 : 261-290

Chiloglanis asperocutis Mutizwa, Bragança & Chakona sp. nov.

Figs 6 , 7

Chiloglanis sp. “rough skin”: Chakona et al. 2018: 76–79.

Type material.

Holotype. • SAIAB 246255 , female specimen 66.0 mm SL, Honde River, Bridge on road to Honde Mission , Pungwe River system, Manicaland Province, Zimbabwe, 18.5438°S, 32.8044°E, 13 December 2014, Albert Chakona, Wilbert Kadye and Taurai Bere, genseq- 1 COI MH 432036 . Paratypes. • SAIAB 201026 , 14 male, 29 female specimens (32.3–77.5 mm SL), Honde River, Pungwe River system, Bridge on road to Honde Mission , Manicaland Province, Zimbabwe, 18.5438°S, 32.8044°E, 13 December 2014, Albert Chakona, Wilbert Kadye and Taurai Bere .

Other material examined.

Specimens detailed in Suppl. material 1.

Diagnosis.

A higher number of primary premaxillary teeth (68–128) readily distinguishes C. asperocutis sp. nov. from all its congeners from southern African that consistently have fewer than 68 primary premaxillary teeth except for C. anoterus and C. carnatus Mutizwa et al., 2024 . Possession of ten closely packed mandibular teeth further distinguishes C. asperocutis from C. fasciatus Pellegrin, 1936 that has eight closely packed mandibular teeth; C. compactus sp. nov., C. bifurcus and C. emarginatus that have eight widely spaced mandibular teeth; C. anoterus , C. paratus Crass, 1960 , and C. pretoriae that have 12 closely packed mandibular teeth; and C. swierstrai Van der Horst, 1931 that has 14 closely packed mandibular teeth. Chiloglanis asperocutis sp. nov. possesses more dorsal fin rays (6–7) compared to C. compactus sp. nov. (5 rays). Possession of eight pectoral fin rays distinguishes C. asperocutis from C. compactus sp. nov. and C. emarginatus that possess seven pectoral fin rays. A deeply forked caudal fin readily separates C. asperocutis sp. nov. from C. compactus sp. nov., C. pretoriae , C. paratus , and C. swierstrai that have shallower fork depths in the caudal fin; C. emarginatus that has an emarginated caudal fin with a very shallow fork; and from C. anoterus that has a caudal fin with no fork due to extended median rays in males and emarginated in females. A caudal fin with an upper lobe shorter than lower lobe distinguish C. asperocutis sp. nov. from C. bifurcus that has a caudal fin with an upper lobe that is longer than the lower lobe. An oral disc with a well-developed mid-ventral cleft distinguishes C. asperocutis sp. nov. from C. swierstrai that lacks a mid-ventral cleft. Chiloglanis asperocutis sp. nov. has a dorsal spine with gently serrated anterior and posterior margins that distinguish it from C. paratus that has a dorsal spine with a serrated posterior margin. Absence of a fleshy skin on the basal portion of the dorsal fin separates C. asperocutis sp. nov. from C. carnatus , a character present in the latter species. Chiloglanis asperocutis sp. nov. is further distinguished from its southern African congeners by long ridge-like tubercles distributed across the dorsal and lateral surfaces of the head and body compared to conical tubercles found in C. compactus sp. nov., C. bifurcus , C. emarginatus , C. fasciatus , C. paratus , C. carnatus , and C. swierstrai ; and the lack of conspicuous tubercles in C. anoterus and C. pretoriae . A narrow caudal peduncle depth distinguishes C. asperocutis sp. nov. (7.5–10.0 % SL) from C. carnatus (11.3–13.2 % SL), C. pretoriae (11.0–13.8 % SL), C. anoterus (12.2 % SL), C. bifurcus (11.1–14.1 % SL), and C. emarginatus (10.2–11.9 % SL) that have deeper caudal peduncles. A narrow mandibular tooth row width separates C. asperocutis sp. nov. (3.6–7.2 % HL) from C. pretoriae (16.0–25.6 % HL), C. anoterus (10.5 % HL), C. bifurcus (10.4–17.3 % HL), C. emarginatus (9.6–13.5 % HL), C. paratus (7.2–7.7 % HL), and C. swierstrai (10.0–16.6 % HL) that have wider mandibular tooth row widths. A longer upper lip length further separates C. asperocutis sp. nov. (11.4–22.2 % HL) from C. emarginatus (6.6–10.6 % HL) and C. swierstrai (7.0–10.5 % HL) that have shorter upper lips.

Description.

Figs 6 , 7 shows general body features of adult male and female C. asperocutis . Morphometric and meristic data for holotype, paratypes, and non-type specimens are presented in Table 3 . Where meristics counts have a range, counts from the holotype are given in parentheses.

Body elongate. Depressed pre-dorsal region, mid-sections more cylindrical, slightly laterally compressed posterior section. Pre-dorsal profile convex, sharply slopping from snout to posterior nostril, gentler slope from poster nostril to dorsal-fin origin. Body greatest depth at dorsal-fin insertion. Post-dorsal profile almost straight to adipose fin insertion, gently concave from adipose-fin origin to caudal fin. Ventral profile gently convex from region just posterior of oral disc to anal-fin origin, gently concave from anal-fin origin to caudal fin.

Skin numerous tubercles spread across body with exception of ventral surface, forming distinct ridge like structures most conspicuous on head dorsum giving skin a distinct “ rough ” texture. Lateral line complete, originating just above horizontal level of orbit, below anterior dorsal fin origin, gently undulating along midlateral of body to base of caudal fin.

Head relatively big; longer than body depth; ~ 2 / 3 of pre-dorsal length. Eye large and oval, orbit lacks free margin; located dorsally, closer to margin of operculum than tip of snout. Interorbital space slightly wider than space between nares spaces. Posterior nares slightly closer together than anterior nares. Anterior nares with short skin flaps on their posterior margins. Posterior nares with short skin flaps along anterior margin. Gill opening restricted, located adjacent to pectoral fin origin.

Mouth inferior, projecting below ventral body surface, upper and lower lips combined into a distinct large oral disc. Oral disc width greater than length. Upper and lower lips with pronounced roundish papillae, largest papillae concentrated around mid-ventral cleft of lower lip. Three unbranched pairs of barbels. Maxillary barbel, originating from lateral region of oral disc, extending to posterior region of oral disc. Lateral mandibular barbel longer than medial mandibular barbel, both integrated into lower lip.

Dentation variable number 68–128 (102) of primary pre-maxillary teeth arranged in 3–5 (4) rows on two ovoid tooth patches. Secondary pre-maxillary teeth small and scattered on posterior surface of premaxillae. Tertiary teeth small and needle-like; in a row near midline of dorsal edge of tooth plate. Up to 10 (10) closely packed mandibular teeth; central teeth projecting higher than outer teeth forming a gentle arc; replacement tooth row emerges anteriorly to functional row, number of mandibular teeth may vary due to loss of teeth and their replacements, but the number does not exceed ten.

Vertebral counts Total vertebrae 27–29 (29), abdominal vertebrae 11–13 (13), caudal vertebrae 15–17 (16).

Urogenital papillae distinctly elongate and sharply pointed in males, reduced to a shallow invagination in females.

Pectoral fin ray count 8, origin adjacent to gill opening; pectoral spine slightly curved, anterior margin smooth; gently serrated posterior margin; pectoral spine length ~ 80 % of longest pectoral-fin ray. Dorsal fin originating in anterior 1 / 3 of body, posterior to pectoral-fin origin, 6–7 (6) branched rays. Dorsal spine, length ~ 80 % of longest dorsal-fin ray, gentle serrations on anterior and posterior margins of the terminal 1 / 4 of dorsal spine. Pelvic fin ray count 7, origin posterior to midpoint between end of dorsal-fin and adipose-fin origin; rounded. Adipose fin relatively small, margin convex, located in posterior 1 / 3 of body, origin just anterior of anal-fin origin, ridge-like tubercles sometimes present on its surfaces. Anal fin ray count 12–13 (13), origin just posterior to origin of adipose fin; terminating just before posterior end of adipose fin; rounded. Caudal fin deeply forked, lobes unequal, lower lobe generally longer, both lobes with gently pointed tips.

Coloration in ethanol dorsal and lateral skin generally dark brown becoming a lighter shade of brown below mid lateral line. Dark melanophores distributed throughout dorsal and lateral surfaces. Dorsal surface has blotches of lighter shades of brown located between orbits and posterior nostril, at dorsal fin insertion, between dorsal and adipose fin, and posterior to adipose fin, all these blotches extend to lateral surface. Lateral surface with large pale blotches such as those extending from dorsal surface. Lateral line clearly visible as a continuous pale brown stripe with very small pale blotches distributed above and below it. Ventral surface pale cream to yellowish in colour with dark melanophores only present at base of pelvic fins. Dorsal and adipose fins dark brown base and middle with hyaline margins. Pectoral fins have dark brown dorsal surfaces and lighter ventral surface, hyaline margins. Pelvic and anal fins pale brown in colour with dark melanophores and hyaline margins. Dark band stretches across middle of upper caudal fin lobe, lower lobe mostly covered by a dark blotch originating from the fin base. Live colouration displayed similar patterns as described in persevered specimens with a few differences. All pale brown sections in live specimens have a golden colour. Live specimens display a range of pigmentation intensity, some specimens are very dark with patterns described in the Coloration in ethanol section being very clear whilst other specimens are lightly coloured (golden) with little pigmentation visible.

Reproduction: there are no dedicated studies on the breeding biology of C. asperocutis , but spawning is likely to begin in summer (October – November) based on the general pattern of other congeners ( Skelton 2001), and other mochokid fishes from this region.

Distribution, habitat, and feeding ecology.

this species is known from multiple localities in the Pungwe and Buzi River systems. It is a rheophilic species that occurs in rocky habitats with fast flowing water. Macroinvertebrates from the families Simuliidae , Chironomidae , Hydropsychidae and Libellulidae were the dominant prey item for this species with algae forming a smaller component of the diet of this species ( Matomela et al 2018).

Etymology.

a combination of the Latin words, aspero, meaning rough, and cutis, meaning skin. The name refers to the distinct ridges on the skin (more pronounced on the head dorsum) which is characteristic of this species.

Figures

Figure 6. Chiloglanis asperocutis female holotype SAIAB 246255. Scale bars: 2 cm.

Figure 7. Chiloglanis asperocutis male paratype SAIAB 201026. Scale bars: 2 cm.