Cambeva betabelardense, Costa & Feltrin & Katz, 2022

Costa, Wilson J. E. M., Feltrin, Caio R. M. & Katz, Axel M., 2022, Two new remarkable and endangered catfish species of the genus Cambeva (Siluriformes, Trichomycteridae) from southern Brazil, European Journal of Taxonomy 794, pp. 140-155 : 148-152

Cambeva betabelardense sp. nov.

urn:lsid:zoobank.org:act:E77B223C-C536-4729-B483-BC9B0AD3E8CE

Figs 2D–F , 5–6

Diagnosis

A small species, maximum recorded adult size 42.7 mm SL, diagnosed by the presence of a dorsal projection adjacent to the opercular odontode patch ( Fig. 2E ) and the combination of the following features: posterior nostril about equidistant from anterior nostril and from orbit; a compact broad autopalatine, its width about equal to its length excluding anterior cartilage and postero-lateral process ( Fig. 2D ); presence of an anterior broad and rounded projection on the interopercle ( Fig. 2E ); six pectoral-fin rays; 12 opercular odontodes; 30–34 premaxillary teeth; 32–34 dentary teeth; anterior jaw teeth incisiform, posterior teeth pointed; largest rays of the dorsal and anal fins shorter than respective fin bases; dorsal and anal fins subtrapezoidal; head width 73.7–78.5% of the head length; interorbital length 21.6–26.2%; mesethmoid thin, its width at the base of cornua about half autopalatine width ( Fig. 2D ); metapterygoid longer than deep, approximately triangular ( Fig. 2E ).

Differential diagnosis

Cambeva betabelardense sp. nov. is distinguished from all other congeners, except C. alphabelardense sp. nov., by the relatively more anterior position of the orbit, making the posterior nostril nearly equidistant from anterior nostril and orbit, a compact broad autopalatine, its width about equal to its length excluding anterior cartilage ( Fig. 2D ; vs. width conspicuously smaller than that length), and the presence of an anterior broad and rounded projection on the interopercle ( Fig. 2E ; vs. never a similar projection). Cambeva betabelardense sp. nov. is distinguished from C. alphabelardense sp. nov. by having more pectoral-fin rays (six vs. five), more opercular odontodes (12 vs. 6 or 7), more teeth on the premaxilla (30–34 vs. 20–23) and dentary (32–34 vs. 24–25), anterior jaw teeth incisiform, posterior teeth pointed (vs. all teeth pointed), largest rays of the dorsal and anal fins shorter than respective fin bases (vs. longer), a narrower head (head width 73.7–78.5% of the head length, vs. 83.5–91.3%), a narrower interorbital distance (21.6–26.2% of the head length, vs. 27.0–31.2%), a thinner mesethmoid, its width at the base of the cornua about one fifth of the distance between tips of cornua ( Fig. 2D ; vs. about one third, Fig. 2A ), and a more slender metapterygoid that is sub-triangular and longer than deep ( Fig. 2E ; vs. sub-rectangular and deeper than long, Fig. 2B ). Cambeva betabelardense sp. nov. also differs from all other congeners by the presence of a dorsal projection on the opercle adjacent to the odontode patch ( Fig. 2E ; vs. absence).

Etymology

The species epithet ʻ betabelardense ʼ (ʻbetaʼ, the second letter of the Greek alphabet, and ʻabelardenseʼ, Portuguese word referring to people born in Abelardo Luz municipality) is an allusion to the second new species described for this area.

Material examined

Holotype BRAZIL • 1 ex., 42.7 mm SL; Santa Catarina State, Abelardo Luz Municipality, stream tributary to middle Rio Chapecó, Rio Uruguai basin ; 26°29′32″ S, 52°20′32″ W; 820 m a.s.l.; 20 Mar. 2021; C.R.M. Feltrin leg.; UFRJ 6995 .

Paratypes (n = 17) BRAZIL • 10 ex., 19.7–38.6 mm SL; same collection data as for holotype; UFRJ 6996 • 3 ex. (C&S), 32.4–37.4 mm SL; same collection data as for holotype; UFRJ 6997 • 2 ex., 33.2–34.8 mm SL; same collection data as for holotype; CICCAA 12707 • 4 ex., 36.8–41.3 mm SL; Santa Catarina State, Abelardo Luz Municipality, stream tributary to middle Rio Chapecó, in front of Parque Quedas de Chapecó; 26°33′08″ S, 52°19′13″ W; 760 m a.s.l.; 20 Mar. 2021; C.R.M. Feltrin leg.; UFRJ 6998 .

Description

GENERAL MORPHOLOGY. Morphometric data appear in Table 2 . Body slender, subcylindrical and slightly depressed anteriorly, compressed posteriorly. Greatest body depth in area just anterior to pelvic-fin base. Dorsal and ventral profile of head and trunk slightly convex, approximately straight on caudal peduncle. Skin papillae minute. Anus and urogenital papilla in vertical through anterior portion of dorsal-fin base. Head trapezoidal in dorsal view. Anterior profile of snout slightly convex in dorsal view. Eye small, dorsally positioned in head, in its anterior half. Posterior nostril located approximately mid-way between anterior nostril and orbital rim. Tip of maxillary and rictal barbels posteriorly reaching anterior margin of interopercular patch of odontodes; tip of nasal barbel posteriorly reaching area between one and two thirds of distance between orbit and opercular patch of odontodes. Mouth subterminal. Jaw teeth 30–34 on premaxilla, 32–34 on dentary, pointed internally to incisiform in external rows, slightly curved, arranged in three irregular rows. Branchial membrane attached to isthmus only at its anteriormost point, in ventral midline. Dorsal and anal fins subtrapezoidal, short, their length smaller than respective fin base; total dorsal-fin rays 11 (ii + II + 7), total anal-fin rays 9 (ii + II + 5); anal-fin origin at vertical through posterior half of dorsal-fin base. Dorsal-fin origin at vertical through centrum of 21 st vertebra; anal-fin origin at vertical through centrum of 24 th vertebra. Pectoral fin subtriangular in dorsal view, posterior margin slightly convex, first pectoral-fin ray slightly projected beyond fin membrane but not forming filament; total pectoral-fin rays 5 (I + 4). Pelvic fin subtruncate, its posterior extremity in vertical just anterior to or through dorsal-fin origin; pelvic-fin bases medially separated by small interspace, about half pelvic-fin base width; total pelvic-fin rays 5 (I + 4). Caudal fin rounded, dorsoventrally symmetrical; total principal caudal-fin rays 13 (I + 11 + I), total dorsal procurrent rays 16–19 (xv–xviii + I), total ventral procurrent rays 12–14 (xi–xiii + I).

LATEROSENSORY SYSTEM. Supraorbital sensory canal continuous, connected to posterior section of infraorbital canal posteriorly. Supraorbital sensory canal with 3 pores: s1, adjacent to medial margin of anterior nostril; s3, adjacent and just posterior to medial margin of posterior nostril; and s6, in transverse line through posterior half of orbit; pore s6 nearer orbit than its paired homologous pore. Single infraorbital sensory canal segment, with two pores, corresponding to pore i10, adjacent to ventral margin of orbit, and pore i11, posterior to orbit; anterior segment of infraorbital canal absent. Postorbital canal with 2 pores: po1, in vertical line above posterior portion of interopercular patch of odontodes, and po2, in vertical line above posterior portion of opercular patch of odontodes. Lateral line of body short, with 2 pores, posterior-most pore in vertical just posterior to pectoral-fin base.

OSTEOLOGY ( Fig. 2D–F ). Mesethmoid thin, its width at cornua bases about half autopalatine width; anterior margin about straight, mesethmoid cornu narrow, with rounded extremity. Lateral ethmoid articulated with autopalatine by broad articular facet. Antorbital thin, narrow and short; sesamoid supraorbital slender, without processes, short, its length about twice antorbital length. Premaxilla sub-trapezoidal in dorsal view, laterally narrowing, moderate in length, longer than maxilla. Maxilla boomerang-shaped, slightly curved. Autopalatine sub-rectangular in dorsal view, broad, its width about equal to its length excluding anterior cartilage; medial margin sinuous, with small projection, lateral margin slightly concave, almost straight; autopalatine posterolateral process triangular in dorsal view, small, about one third autopalatine length. Metapterygoid moderate in length, thin, subtriangular, longer than deep; anteroventral process articulating with adjacent expansion in quadrate. Quadrate slender, dorsal process with constricted base, dorsoposterior margin separated from hyomandibula outgrowth by small interspace. Hyomandibula long, with well-developed anterior outgrowth; middle portion of dorsal margin of hyomandibula slightly concave. Opercle long, longer than interopercle, opercular odontode patch moderate, its depth slightly shorter than dorsal hyomandibula articular facet, with 11 or 12 odontodes; odontodes pointed, nearly straight, transversely arranged; dorsal projection adjacent to odontode patch; dorsal process of opercle short, extremity rounded; opercular articular facet for hyomandibula with prominent sub-rectangular projection, articular facet for preopercle well developed, rounded. Interopercle moderate, about two thirds hyomandibula length, with pronounced anterior rounded projection; interopercular odontodes; odontodes pointed, arranged in irregular longitudinal rows. Preopercle compact, with short ventral projection. Parurohyal robust, lateral process broad, subtriangular, laterally directed, tip pointed; parurohyal head well-developed, with prominent anterolateral paired process; middle foramen rounded; posterior process short, about one third of distance between anterior margin of parurohyal and anterior insertion of posterior process. Branchiostegal rays 8. Vertebrae 37. Ribs 12. Two dorsal hypural plates corresponding to hypurals 3 + 4 + 5; single ventral hypural plate corresponding to hypurals 1 + 2 and parhypural.

COLOURATION IN ALCOHOL ( Fig. 5 ). Flank, dorsum and head side pale yellow, with rounded dark brown blotches, often longitudinally coalesced, larger and darker on middle and dorsal portions of flank. In some specimens, blotches darker, smaller and not coalesced. Nasal and maxillary barbels dark brown, rictal barbel pale yellowish brown. Venter and ventral surface of head white. Fins hyaline with dark grey spots.

COLOURATION IN LIFE. Similar to colouration in alcohol, but with paler colours.

Distribution and habitat

Cambeva betabelardense sp. nov. is only known from two localities in the type locality area, in the middle Rio Chapecó drainage, Rio Uruguai basin, southern Brazil ( Fig. 3 ), at altitudes between about 760 and 820 m a.s.l. At both localities, the stream was about 8 m wide, with bottom comprising small stones and gravel ( Fig. 6 ). Cambeva betabelardense sp. nov. was collected in shallow places, about 30 cm deep, on the gravel bottom and associated vegetal remnants. Some vestiges of stream siltation at the type locality, probably as a result of the intense process of deforestation associated with soya plantations in the region, may be indicative that C. betabelardense sp. nov. is an endangered species.

Figures

Fig. 2. Osteological structures. A–C. Cambeva alphabelardense sp. nov., paratype (UFRJ 6993). D–F. Cambeva betabelardense sp. nov., paratype (UFRJ 6996). A, D. Mesethmoidal region and adjacent structures, left and middle portions, dorsal view. B, E. Left jaw suspensorium and opercular series, lateral view. C, F. Parurohyal, ventral view. Abbreviations of structures indicated by arrows are: amp = anteroventral metapterygoid process; doe = dorsal opercular expansion; iap = anterior projection of interopercle. Heavier stippling represents cartilaginous areas. Scale bar: 1 mm.

Fig. 5. Cambeva betabelardense sp. nov., holotype (UFRJ 6995), 42.7 mm SL. A. Left lateral view. B. Dorsal view. C. Ventral view.

Fig. 6. Type locality of Cambeva betabelardense sp. nov.

Fig. 3. Map of geographical distribution of Cambeva alphabelardense sp. nov. and C. betabelardense sp. nov.