Chiloglanis compactus 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 compactus Mutizwa, Bragança & Chakona sp. nov.

Figs 8 , 9

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

Type material.

Holotype. • SAIAB 246256 , male, right middle cut, 44.4 mm SL, Makanga River Bridge on road to Hauna growth point , Pungwe River system, Manicaland Province, Zimbabwe, 18.5438°S, 32.801°E, 16 December 2014, Albert Chakona, Wilbert Kadye and Taurai Bere, genseq- 1 COI MH 432044 . Paratypes. • SAIAB 210377 , 10 males (29.8–37.5 mm SL), 2 females (29.1–40.3 mm SL), Makanga River bridge on road to Hauna growth point , Pungwe River system, Manicaland Province, Zimbabwe, 18.5438°S, 32.801°E, 16 December 2014, Albert Chakona, Wilbert Kadye and Taurai Bere .

Other material examined.

Specimens detailed in Suppl. material 1.

Diagnosis.

Chiloglanis compactus sp. nov. attains the smallest size (<46 mm SL) for all congeners currently known from southern Africa. Possession of seven pectoral fin rays in C. compactus sp. nov. distinguishes this species from C. asperocutis , C. carnatus , C. anoterus , C. fasciatus , C. paratus , C. pretoriae , and C. swierstrai that all have eight pectoral fin rays. Possession of eight widely spaced mandibular teeth further distinguishes C. compactus sp. nov. from C. fasciatus (eight closely packed mandibular teeth); C. asperocutis and C. carnatus (ten closely packed mandibular teeth); C. anoterus , C. paratus , and C. pretoriae (12 closely packed mandibular teeth); and C. swierstrai (14 closely packed mandibular teeth). Fewer primary premaxillary teeth in C. compactus sp. nov. (31–53) readily distinguished it from C. asperocutis (68–128) and C. anoterus (86). Fewer dorsal fin rays (5) readily distinguish C. compactus sp. nov. from C. asperocutis (6–7). A relatively shallow forked tail and rounded caudal fin lobes readily separate C. compactus sp. nov. from C. asperocutis , C. carnatus , and C. fasciatus (deeply forked caudal fin with pointed lobes); C. emarginatus (emarginated caudal fin with 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 lower caudal fin lobe longer than the upper lobe separates C. compactus sp. nov. from C. bifurcus that has a longer upper caudal fin lobe. A well-developed mid-ventral cleft in the oral disc of C. compactus sp. nov. distinguishes it from C. swierstrai that lacks a mid-ventral cleft. Gently serrate anterior and posterior margins of the dorsal spine in C. compactus sp. nov. distinguish it from C. paratus that has a dorsal spine serrated only on the posterior margin. Absence of a fleshy skin on the basal portion of the dorsal fin separates C. compactus sp. nov. from C. carnatus , a character present in the latter species. Conical tubercles distributed across dorsal and lateral surfaces of the head and body distinguish C. compactus sp. nov. from C. asperocutis with ridge like tubercles; C. anoterus and C. pretoriae that lack conspicuous tubercles. A deep caudal peduncle distinguishes C. compactus sp. nov. (10.0–12.4 % SL) from C. asperocutis (7.5–10.0 % SL), C. fasciatus (7.5–8.8 % SL), C. paratus (9.6–9.9 % SL), and C. swierstrai (7.2–8.7 % SL) that have narrower caudal peduncles. A longer dorsal-fin base separates C. compactus sp. nov. (9.9–14.2 % SL) from C. swierstrai (7.5–9.6 % SL) and C. anoterus (8.6 % SL) that possess shorter dorsal-fin bases. Shorter lower lips distinguish C. compactus sp. nov. (17.5–22.6 % HL) from C. pretoriae (22.4–27.7 % HL), C. anoterus (25.1 % HL), C. emarginatus (23.5–28.8 % HL), and C. paratus (22.8–27.6 % HL) that have longer lower lips. A narrow mandibular tooth row separates C. compactus sp. nov. (5.6–10.4 % HL) from C. asperocutis (3.6–7.2 % HL), C. pretoriae (16.0–25.6 % HL), C. bifurcus (10.4–17.3 % HL), and C. swierstrai (10.0–16.6 % HL) that possess greater mandibular tooth row widths.

Description.

Figs 8 , 9 shows general body features of adult male and female C. compactus . Morphometric and meristic data for holotype, paratypes and non-type specimens are presented in Table 4 . Where meristics counts have a range counts from the holotype are given in parentheses.

Body short and rotund. Depressed pre-dorsal region, mid-sections more cylindrical, slightly laterally compressed posterior section. Pre-dorsal profile convex, almost continuous rounded profile from snout to dorsal-fin origin. Body greatest depth at dorsal-fin insertion. Post-dorsal profile convex to adipose fin insertion, becoming gently concave from adipose-fin origin to caudal fin. Ventral profile convex from region just posterior of oral disc to anal-fin origin, becoming gently concave from anal-fin origin to caudal fin.

Skin numerous conical tubercles spread across body with exception of ventral surface. Lateral line complete, originating above horizontal level of orbit, below anterior dorsal fin origin, almost completely straight 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 wider than space between nares spaces. Posterior nares slightly closer together than anterior nares. Anterior nares with short skin flaps on posterior margin. 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 pairs of barbels. Maxillary barbel unbranched, 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 31–53 (44) of primary pre-maxillary teeth arranged in 2–3 (3) 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 8 (6) spaced out mandibular teeth; replacement tooth row emerges anteriorly to the functional row, number of mandibular teeth may vary due to loss of teeth and their replacement, but the number hardly ever exceeds 8.

Vertebral counts Total vertebrae 27–29 (28), abdominal vertebrae 11–12 (11), caudal vertebrae 17–18 (17)

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

Pectoral fin ray count 7, 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, five branched rays, conical tubercles sometime present on its surfaces. Dorsal spine, length ~ 80 % of longest dorsal-fin ray, gentle serrations on anterior and posterior margins of 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, conical 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 with shallow fork, lobes unequal with lower slightly longer, both lobes rounded, conical tubercles sometime present on their surfaces.

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 large blotches of lighter shades of brown located at base of dorsal fin, between dorsal and adipose fin, and posterior end of adipose fin; these blotches extend to lateral surface. Lateral surface with large pale blotches such as those extending from the dorsal surface. Additional large blotches on lateral surface are found below lateral line above pelvic fin, anal fin and caudal peduncle. Approximately seven small circular blotches just above lateral line, two or three similar blotches found above each of them. Approximately four small circular blotches below the lateral line distributed from below dorsal fin to pelvic fin. Lateral line clearly visible as a continuous pale brown stripe. Ventral surface pale cream to yellowish in colour with dark melanophores only present at base of pelvic fins and caudal peduncle. Dorsal and adipose fins 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 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 the preserved specimens with a few differences. 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 with little pigmentation visible.

Reproduction: there have been no dedicated studies on the breeding biology of C. compactus , 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 occurred at multiple localities in the Pungwe and Buzi river systems with the majority of the collections occurring at high elevation. It is a rheophilic species that occurs in rocky habitats with fast flowing water. Its diet was not examined.

Etymology.

the name is drawn from the word compact which is inspired by the short and rotund body shape of this species as well as it being the smallest of all the currently known congeners in southern Africa.

Figures

Figure 8. Chiloglanis compactus male holotype SAIAB 246256. Scale bars: 2 cm.

Figure 9. Chiloglanis compactus female paratype SAIAB 210377. Scale bars: 2 cm.