Cambeva diffusa, E. & Costa & M. & Feltrin & Katz, 2021

Costa, Wilson J. E. M., Feltrin, Caio R. M. & Katz, Axel M., 2021, Field inventory reveals high diversity of new species of mountain catfishes, genus Cambeva Katz, Barbosa, Mattos & Costa, 2018 (Siluriformes: Trichomycteridae), in south-eastern Serra Geral, southern Brazil, Zoosystema 43 (28), pp. 659-690 : 662-664

Cambeva diffusa n. sp.

( Figs 1 , 11A , 12A , 13A ; Table 1 )

urn:lsid:zoobank.org:act:5C3D95DE-504C-49EB-B20D-83B9D446381A

MATERIAL EXAMINED. — Holotype. Brazil • 1 ex., 112.3 mm SL; Santa Catarina state: Urubici Municipality: Rio Urubici, Rio Canoas drainage, Rio Uruguai basin; 28°01’37”S, 49°35’20”W; about 935 m asl; C. R. M. Feltrin; 8.II.2021; UFRJ 6968 .

Paratypes. Brazil • 4 ex., 19.0- 49.2 mm SL; collected with holotype; UFRJ 6980 • 3 ex. (C&S), 26.0- 103.4 mm SL; collected with holotype; UFRJ 6981 • 4 ex., 22.4-72.4 mm SL; same locality and collector as holotype; 14.III.2021; UFRJ 6978 • 6 ex., 21.7-55.9 mm SL; upper Rio Canoas , road between Urubici and Rio dos Bugres; 27°59’24”S, 49°32’39”W; about 905 m asl; C. R. M. Feltrin; 14.III.2021; UFRJ 6977 • 5 ex., 30.3-67.9 mm SL; same data as UFRJ 6977; CICCAA 04111 • 1 ex., 43.9 mm SL; same locality and collector as UFRJ 6977; 8.II.2021; UFRJ 6982 • 7 ex., 29.4-65.1 mm SL; stream tributary to Rio Urubici ; 28°00’52”S, 49°35’31”W; about 920 m asl; C. R. M. Feltrin; 14.III.2021; UFRJ 6979 .

DIAGNOSIS. — Cambeva diffusa n. sp. is distinguished from all other species of the C. balios complex by the presence of a lighter general colouration, highly differing by the presence of a great concentration of small dark brownish grey dots in a superficial skin layer, contrasting with rounded diffuse pale grey spots, almost inconspicuous, in a deeper layer ( Fig. 1 ; vs never a similar colouration, Fig. 2 ; see also Ferrer & Malabarba 2013: fig. 1). Cambeva diffusa n. sp. is similar to C. pericoh n. sp. and distinguished from C. balios in having a slightly posteriorly folded extremity of the dorsal process of the opercle ( Fig. 12A , vs unfolded), a narrow postero-dorsal projection on the preopercle ( Fig. 12A , vs no projection), and eight branchiostegal rays (vs nine). Cambeva diffusa n. sp. differs from C. pericoh n. sp. in having more dorsal procurrent caudal-fin rays (17, vs 13 or 14), fewer ribs (12, vs 15), and opercular and interopercular postero-dorsal odontodes distinctively wider and more curved than other odontodes ( Fig. 12A ; vs opercular and interopercular posterodorsal odontodes only slightly wider and more curved than other odontodes, Fig. 12B ).

DISTRIBUTION. — Cambeva diffusa n. sp. occurs in the western open plateau. It is known from three localities in the upper Rio Canoas drainage, Rio Uruguai basin, in altitudes between about 910 and 940 m asl ( Fig. 14 ).

ETYMOLOGY. — From the Latin, the name diffusa (diffuse) refers to the colour pattern of the new species, with diffuse grey spots in a deeper skin layer, overlapped by a great concentration of minute brownish grey dots, conferring a unique general colouration that is lighter than in close related congeners.

DESCRIPTION

General morphology

Morphometric data in Table 1 . Body moderately slender, subcylindrical anteriorly to compressed posteriorly. Greatest body depth in area just anterior to pelvic-fin base. Dorsal and ventral profiles of head and trunk slightly convex, approximately straight on caudal peduncle. Skin papillae minute. Anus and urogenital papilla in vertical through anterior third of dorsal-fin base. Head trapezoidal in dorsal view, anterior profile of snout convex. Eye small, dorsally positioned in anterior half of head. Posterior nostril located nearer anterior nostril than orbital rim. Tip of maxillary barbel reaching middle of interopercular patch of odontodes; tip of rictal barbel reaching area just anterior to interopercular patch of odontodes; tip of nasal barbel reaching anterior portion of orbit. Mouth subterminal. Jaw teeth slightly pointed to incisiform, slightly curved in premaxilla and strongly curved in dentary, irregularly arranged, 36-45 in premaxilla, 33-46 in dentary. Branchial membrane attached to isthmus only at its anterior point. Branchiostegal rays 8. Cranial fontanels present, posterior fontanel long, anteriorly extending between frontals to reach transverse line close to lateral sphenotic process. Dorsal and anal fins subtriangular, distal margin slightly convex; total dorsal-fin rays 12 (iii + II + 7), total anal-fin rays 10 (iii + II + 5); anal-fin origin in vertical slightly posterior to middle dorsal-fin base. Dorsal-fin origin in vertical through centrum of 21st vertebra; anal-fin origin in vertical through centrum of 25th vertebra. Pectoral fin subtriangular in dorsal view, posterior margin slightly convex, first pectoral-fin ray not terminating in filament; total pectoral-fin rays 7 (I + 6). Pelvic fin subtruncate, its extremity in vertical through dorsal-fin origin or just anterior to it; pelvic-fin bases medially in contact; total pelvic-fin rays 5 (I + 4). Caudal fin subtruncate, postero-dorsal and postero-ventral extremities rounded; total principal caudal-fin rays 13 (I + 11 + I), total dorsal procurrent rays 17 (xvi + I), total ventral procurrent rays 12-13 (xi-xii + I). Vertebrae 40-42. Ribs 12. Two dorsal hypural plates, corresponding to hypurals 4 + 5 and 3, respectively; single ventral hypural plate corresponding to hypurals 1 and 2 and parhypural.

Latero-sensory system

Supraorbital sensory canal continuous, connected to infraorbital sensory canal posteriorly. Supraorbital sensory canal with 3 pores: s1, adjacent to medial margin of anterior nostril; s3, adjacent to medial margin of posterior nostril; and s6, on middle part of dorsal surface of head, in transverse line just posterior to orbit; pore s6 nearer midway between orbit and its paired homologous pore. Infraorbital sensory represented by single segment, with two pores: pore i10, adjacent to ventral margin of orbit, and pore i11, posterior to orbit. 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.

Mesethmoidal region ( Fig. 11A )

Mesethmoid robust, its anterior margin about straight to gently concave; mesethmoid cornu subtriangular in dorsal view, extremity pointed; narrow lateral flap on intersection between cornu and main bone axis. Minute lateral projection on lateral ethmoid margin close to sesamoid supraorbital. Antorbital thin, short, drop-shaped; sesamoid supraorbital flattened, its length about thrice antorbital length, with lateral pointed expansion on its anterior half. Premaxilla sub-trapezoidal in dorsal view, slightly laterally narrowing, slightly longer than maxilla. Maxilla boomerang-shaped, slender, slightly curved. Autopalatine sub-rectangular in dorsal view, moderate in width, longer than wide, with deep notch on medial margin, lateral margin straight to slightly curved at posterolateral process base; autopalatine posterolateral process subtriangular in dorsal view, its length shorter than osseus portion of autopalatine length excluding posterolateral process.

Cheek region ( Fig. 12A )

Metapterygoid thin, subtriangular, large, its largest length greater than horizontal length of quadrate excluding dorsal process. Quadrate slender, dorsal process with constricted base, dorsoposterior margin in contact with hyomandibula outgrowth. Hyomandibula long, with well-developed anterior outgrowth; middle portion of dorsal margin of hyomandibula slightly concave. Opercle broad, opercular odontode patch depth about three fourths of dorsal hyomandibula articular facet, with 13-14 odontodes; odontodes pointed, straight to curved, arranged in irregular transverse rows, postero-dorsal odontodes larger and distinctively more curved; dorsal process of opercle short, extremity slightly posteriorly folded; opercular articular facet for hyomandibula with small, subtrapezoidal flap, articular facet for preopercle minute. Interopercle moderate, about two thirds hyomandibula length, anterior margin deeply concave, ventrally terminating in anteriorly directed prominent process; interopercular odontode patch with 18-20 pointed odontodes, arranged in irregular longitudinal rows, postero-dorsal odontodes larger and strongly curved, remaining odontodes nearly straight to slightly curved. Preopercle compact, with short ventral flap and narrow postero-dorsal projection.

Parurohyal ( Fig. 13A )

Robust, lateral process broad, posterior margin slightly convex, latero-posteriorly directed, extremity truncate; parurohyal head well-developed, with prominent anterolateral paired process; middle foramen small, round; posterior process long, about three fifths of distance between anterior margin of parurohyal and anterior insertion of lateral process.

Colouration in alcohol ( Fig. 1 )

Flank, dorsum and head side pale yellow, with great concentration of small dark brownish grey dots in superficial skin layer, and rounded diffuse pale grey spots, almost inconspicuous, in deeper layer. Venter with paler dots; ventral part of head greyish white. Barbels grey. Fins pale grey with small dark brownish grey dots. In juvenile species, dark grey spots over whole flank.

Figures

FIG. 1. — Cambeva diffusa n. sp., UFRJ 6968, holotype, 112.3 mm SL.: A, left lateral view; B, dorsal view; C, ventral view.

FIG. 11. — Mesethmoidal region and adjacent structures, left and middle portions, dorsal view: A, Cambeva diffusa n. sp.; B, Cambeva pericoh n. sp.; C, Cambeva imaruhy n. sp.; D, Cambeva orbitofrontalis n. sp.; E, Cambeva panthera n. sp.; F, Cambeva grisea n. sp.; G, Cambeva duplimaculata n. sp.; H, Cambeva longipalata n. sp.; I, Cambeva notabilis n. sp.; J, Cambeva tropeira; K, Cambeva urubici n. sp. Larger stippling represents cartilaginous areas.

FIG. 12. — Left suspensorium and opercular series, lateral view: A, Cambeva diffusa n. sp.; B, Cambeva pericoh n. sp.; C, Cambeva imaruhy n. sp.; D, Cambeva orbitofrontalis n. sp.; E, Cambeva panthera n. sp.; F, Cambeva grisea n. sp.; G, Cambeva duplimaculata n. sp.; H, Cambeva longipalata n. sp.; I, Cambeva notabilis n. sp.; J, Cambeva urubici n. sp. Abbreviations of structures indicated by arrows are: iac, interopercular anterior concavity; ppe, preopercular postero-dorsal expansion; odc, opercular dorsal constriction; odp, opercular dorsal process; ppp, parurohyal posterior process.Larger stippling represents cartilaginous areas.

FIG. 13. — Urohyal, ventral view.A, Cambeva diffusa n. sp.; B, Cambeva pericoh n. sp.; C, Cambeva imaruhy n. sp.; D, Cambeva orbitofrontalis n. sp.; E, Cambeva panthera n. sp.; F, Cambeva grisea n. sp.; G, Cambeva duplimaculata n. sp.; H, Cambeva longipalata n. sp.; I, Cambeva notabilis n. sp.; J, Cambeva urubici n. sp.

FIG. 2. — Cambeva pericoh n. sp., UFRJ 6969, holotype, 97.3 mm SL: A, left lateral view; B, dorsal view; C, ventral view.

FIG. 14. — Map of geographical distribution of Cambeva Katz, Barbosa, Mattos & Costa, 2018 in the southeastern nucleus of the Serra Geral (SESG), southern Brazil.