Cambeva damnata, Costa & Azevedo-Santos & Ottoni & Vilardo & Katz, 2024

Costa, Wilson J. E. M., Azevedo-Santos, Valter M., Ottoni, Felipe Polivanov, Vilardo, Paulo J. & Katz, Axel M., 2024, A new species of the Cambeva variegata group (Siluriformes: Trichomycteridae) from the Serra do Espinhaço, south-eastern Brazil, under severe risk of extinction, Zootaxa 5497 (3), pp. 426-434 : 427-432

Cambeva damnata sp. nov.

lsid:zoobank.org:pub: 182FFEA2-1CA9-4552-AB0C-BA3CF55ACA24

( Figs. 1–2 , Table 1 )

Cambeva sp. 5 ( Costa et al. 2024: fig. 1 [relationships], fig. 2 [cephalic latero-sensory system], figs. 3C, F, 4C, 5C, 7E, G, 8C [osteology], fig. 6 [distribution]).

Holotype: UFRJ 12967, 46.5 mm SL; Brazil: Minas Gerais State: Nova Lima Municipality: Córrego do Jambreiro, Rio das Velhas drainage, Rio São Francisco basin, in the treck to Cachoeira do Boa Vista , 19°58’29”S 43°51’39”W, about 765 m asl; A.M. Katz, F. P. Ottoni and P. J. Vilardo, 11 June 2022.

Paratypes: UFRJ 12967, 6 ex., 18.0– 35.5 mm SL; UFRJ 12968, 22 ex., 16.2–45.4 mm SL; UFRJ 12983, 9 ex., 20.9–53.5 mm SL; UFRJ 13654, 4 ex. (C&S), 42.2–46.5 mm SL; CICCAA 07950, 10 ex., 26.0– 45.9 mm SL; all collected with the holotype. UFRJ 12965, 7 ex., 15.4–30.6 mm SL; UFRJ 12966, 15 ex., 26.0– 39.6 mm SL; UFRJ 12982, 3 ex., 32.2–46.4 mm SL; Brazil: Minas Gerais State: Raposos Municipality: Ribeirão da Prata, Rio das Velhas drainage, Rio São Francisco basin, 19°58’26”S 43°47’47”W, about 730 m asl; same collectors as holotype, 12 June 2022 .

Diagnosis: Cambeva damnata is distinguished from all other congeners, except species of the CVG clade (i.e., C. concolor and C. variegata ), by the presence of a prominent adipose-like skin crest on the dorsal margin of the caudal peduncle (vs. skin crest absent), an interrupted supraorbital canal (vs. continuous), and a small premaxilla, smaller than the maxilla, with an accentuated constriction on its lateral portion (vs. premaxilla larger than the maxilla or with similar length, without a lateral constriction). Cambeva damnata differs from all other species of CVG by having more interopercular odontodes (37–44 vs. 26–31); from C. concolor and C. variegata by having a minute pectoral-fin filament, about 10 % of the pectoral-fin length or less (vs. about 20–30 %) and the dorsal-fin origin at the vertical through the centrum of the 16th vertebra (vs. 17th); from C. concolor by having a spotted colour pattern (vs. homogeneous pale yellow) and a longer pectoral fin (pectoral-fin length 15.1–17.7 % SL vs. 12.3–13.7 % SL); and from C. variegata by having a more slender body, more conspicuous in specimens between about 45 and 50 mm SL (body depth 12.8–14.8 % SL in C. damnata vs. 16.6–21.2 % SL in C. variegata ), and no sexual dimorphism in colour pattern (vs. sexual dimorphism in colour pattern, with males paler, without large dark brown blotches, and females with large darker spots highly contrasting with light yellow interspaces).

Description: Morphometric data in Table 1 . Body relatively slender, anterior portion of trunk subcylindrical, posterior one compressed. Greatest body depth situated at midway of distance between pectoral and the pelvic-fin bases. Dorsal profile of trunk slightly convex between nape and dorsal-fin origin, about straight at dorsal-fin base insertion, weakly convex on caudal peduncle. Ventral profile of trunk approximately straight. Anus and urogenital papilla opening located at vertical through area just anterior to middle of dorsal-fin base. Lateral line canal of trunk short, restricted to anterior-most part of flank, with two pores. Thirty-five or 36 vertebrae and 11 ribs.

Head sub-trapezoidal in dorsal view, with anterior profile of snout slightly convex in dorsal view. Eye moderately large, dorsally positioned on head, nearer posterior margin of opercle than snout tip. Distance between anterior and posterior nostrils shorter than distance between posterior nostril and orbital rim. Barbels moderately long; tip of nasal barbel reaching area between orbit and opercular patch of odontodes, tip of maxillary and rictal barbels reaching posterior portion of interopercular patch of odontodes or area just posterior to it. Mouth subterminal. Lateral fleshy lobes of mouth relatively large, its largest length about half length of lower jaw excluding lobes. Jaw teeth incisiform, arranged in two rows. Total of 11–15 teeth on outer premaxillary row, 12 or 13 on inner row, nine or ten teeth on outer dentary row, 17–20 on inner row. Ventral surface of head covered by minute skin papillae. Branchial membrane thickened, attached to isthmus only at its anterior-most point, in ventral midline. Total of seven branchiostegal rays. Odontodes always conical, straight and arranged in irregular longitudinal in interopercle, straight to slightly curved and arranged in transverse rows in opercle. Total of 13–15 opercular odontodes, 37–44 interopercular odontodes.

Fins well-developed, with thickened bases. Dorsal fin relatively long and deep, subtriangular, with 12 (ii + II + 8) rays. Dorsal-fin origin at midway between nape and caudal-fin base. Anal fin smaller than the dorsal fin, subtriangular, with nine (ii + II + 5) rays. Anal-fin origin at vertical through posterior portion of dorsal-fin base, at base of sixth branched ray. Base of first dorsal-fin ray at vertical through centrum of 16th vertebra, base of first anal-fin ray at vertical through centrum of 22nd vertebra. Pectoral fin subtriangular in dorsal view. First pectoral-fin slightly extending beyond fin membrane to form short terminal filament, its length about 10 % of pectoral-fin length or less. Eight (I + 7) pectoral-fin rays. Pelvic fin sub-oval, its posterior extremity reaching vertical through middle of dorsal-fin base, surpassing anus position. Pelvic-fin bases medially separated by interspace corresponding to about half pelvic-fin base width. Five (I + 4) pelvic-fin rays. Caudal fin subtruncate with posterior corners rounded. Thirteen (I + 11 + I) principal caudal-fin rays, 17–19 (xvi-xviii + I) dorsal procurrent rays, and nine or ten (viii–ix + I) ventral procurrent rays; one or two loose minute rays positioned anteriorly to dorsal procurrent rays, within prominent skin crest on dorsal surface of caudal peduncle. Caudal skeleton comprising two triangular hypural plates, dorsal plate, corresponding to the hypural bones 3 + 4 + 5, and ventral plate corresponding to hypural bones 1 + 2 and parhypural.

Colouration in life ( Fig. 2 ). In specimens above about 40 mm SL ( Figs 2f–h ), flank light yellowish grey with large dark brown blotches, irregularly shaped, often coalesced with neighbouring spots. Dorsum predominantly dark brown, contrasting with light yellowish grey spots. Venter and ventral surface of head yellowish white, without vestige of dark pigmentation. Dorsal and lateral regions of head predominantly dark brown, with unpigmented area on infraorbital region, extending to entire interopercular patch of odontodes and posterior portion of opercular patch of odontodes. Nasal barbel dark grey, maxillary and rictal barbels light grey. Iris dark brown, with narrow yellow circle around pupil. Fins hyaline, with concentration of melanophores on pectoral and unpaired fins, and anterobasal portion of adipose-like skin crest of caudal peduncle. Specimens between about 20 and 35 mm SL ( Figs 2a–e ) differ from larger ones by flank spots being smaller, sub-rectangular, arranged in longitudinal row on flank midline line of in another one on area between dorsum and flank, often each one alternating longitudinally with small pale golden dots. In specimens about 15 mm SL, dark pigmentation of body restricted to narrow black stripe along flank longitudinal midline.

Colouration in alcohol ( Fig. 1 ). Similar to live specimens, but brown marks paler and golden dots absent.

Etymology: From the Latin, the name damnata means condemned and refers to the risks that the species faces with the plans for mining activities at the Serra do Curral and urban expansion (see conservation notes below).

Distribution and habitat: Cambeva damnata is known from two small urban streams that are tributaries of the Rio das Velhas drainage, Rio São Francisco basin, in Minas Gerais State, south-eastern Brazil: the Córrego do Jambreiro in the Nova Lima Municipality, the type locality, and the Ribeirão da Prata, in the Raposos Municipality. Nova Lima and Raposos are neighbouring municipalities, with these two collection sites being at a straight line distance of 6.7 km ( Fig. 3 ).

The Córrego do Jambreiro ( Figs. 4a, b ) is located at the Serra do Curral, a small mountain area that is part of the Serra do Espinhaço. At the type locality, about 765 m asl, the water flow is fast to moderate and the substrate is predominantly composed of gravel and rocks of different sizes. Along the stream course, there were some areas where the substrate was composed of sand and leaf litter, especially in areas with slower water flow. Along the entire collecting site, the bank was covered by riparian forest. The specimens were captured using the following collection procedure: one collector lifted and moved the rocks and gravel using his hands and feet, while another collector lifted the hand net. This suggests that the species lives buried under gravel and rocks.

The collecting site at Ribeirão da Prata ( Figures 4c, d ) is located at 730 m asl, has moderate water flow and substrate composed of mud, sand, leaf litter, tree trunks, gravel and rocks, depending on the area. This site is situated in an area with more intense urbanization process, with houses occupying banks and surroundings. Consequently, sewage is dumped directly into the stream, and the stream banks are heavily deforested. The specimens were found inhabiting areas of gravel and rocks, and they were collected similarly as described above.

Conservation notes: Cambeva damnata occurs in a region subject to strong pressure from human activities, such as mining, deforestation, and urban expansion. The Córrego do Jambreiro holds its headwaters in the Serra do Curral (see above), a mountain subjected to mining activities. The impoundment is known as the Serra do Taquaril Mining Complex (Complexo Minerário Serra do Taquaril, in Portuguese), and the headwaters of a tributary of Córrego do Jambreiro is very close to the area that will receive the influence of mining activities. Mining is responsible for siltation, destruction of riparian vegetation, and water contamination downstream ( Azevedo-Santos et al. 2021). Therefore, plans for mining on the Serra do Curral may put populations of C. damnata at risk of extinction. On the other hand, the Ribeirão da Prata area is under an intense process of urban expansion, which presently is a strong regional threat ( Azevedo-Santos et al. 2023). Therefore, since the only two localities where C. damnata is known to occur are being dramatically affected by anthropogenic features, this species may be seriously threatened with extinction.

Figures

FIGURE 1. Cambeva damnata sp. nov., holotype, UFRJ 7026, 12967, 46.5 mm SL. (a) lateral view; (b) dorsal view; (c) ventral view.

FIGURE 2. Ontogenetic variation of colouration in Cambeva damnata sp. nov., paratypes, UFRJ 12983: (a) 20.9 mm SL; (b) 21.4; (c) 28.3; (d) 30.7; (e) 33.9 mm SL; (f) 43.2 mm SL; (g) 44.3 mm SL; (h) 53.5 mm SL.

FIGURE 3. Geographical distribution of the Cambeva variegata species group: (1) Cambeva concolor (Costa, 1992); (2) Cambeva variegata (Costa, 1992); (3) Cambeva damnata sp. nov. Stars indicate type localities.

FIGURE 4. Biotopes of Cambeva damnata sp. nov. in (a,b) Córrego do Jambreiro, Município de Nova Lima, (c,d) Ribeirão da Prata, Município de Raposos: (a, c) out of water general view; (b,d) underwater view.