Vanmanenia marmorata Deng & Zhang 2021

Deng, Shuqing & Zhang, E, 2021, Vanmanenia marmorata, a new species of loach (Teleostei: Gastromyzontidae) from the middle Chang-Jiang Basin in Guizhou Province, south China, Biodiversity Data Journal 9, pp. 72432-72432 : 72432

Vanmanenia marmorata Deng & Zhang 2021 sp. n.

Materials

Type status: Holotype. Occurrence: recordNumber: IHB2017060069; recordedBy: Changting An ; individualCount: 1; lifeStage: adult; Taxon : scientificName: Vanmanenia marmorata; kingdom: Animalia ; phylum: Chordata ; class: Actinopterygii ; order: Cypriniformes ; family: Gastromyzontidae ; genus: Vanmanenia ; Location : waterBody: the Chang-Jiang basin; country: China; stateProvince: Guizhou Province; county: Jiangkou County; locality: the Chenshui River , a tributary of the Yuan-Jiang drainage ; verbatimElevation: 866.1 m a.s.l.; verbatimCoordinates: 27°52′16.94″N, 108°37'15.6''E; georeferenceSources: Google Earth ; Identification : identifiedBy: Shuqing Deng ; dateIdentified: 2017-9-20; Event: eventDate: 2017-6-22; Record Level: collectionCode: fish; basisOfRecord: Preserved Specimen Type status: Paratype. Occurrence: recordNumber: IHB2017060068, 5189-5191; recordedBy: Changting An ; individualCount: 4; Taxon : scientificName: Vanmanenia marmorata; kingdom: Animalia ; phylum: Chordata ; class: Actinopterygii ; order: Cypriniformes ; family: Gastromyzontidae ; genus: Vanmanenia ; Location : waterBody: the Chang-Jiang basin; country: China; stateProvince: Guizhou Province; county: Jiangkou County; locality: the Chenshui River , a tributary of the Yuan-Jiang drainage ; verbatimElevation: 866.1 m a.s.l.; verbatimCoordinates: 27°52′16.94″N, 108°37'15.6''E; georeferenceSources: Google Earth ; Identification : identifiedBy: Shuqing Deng ; dateIdentified: 2017-9-20; Event: eventDate: 2017-6-22; Record Level: collectionCode: fish; basisOfRecord: Preserved Specimen

Description

Morphometric measurements for specimens examined are given in Table 1 . See Fig. 1 a-c for lateral, dorsal and ventral view of body.

Body elongate and slightly compressed, with greatest depth at dorsal-fin origin and least depth at caudal-fin base. Dorsal profile of head rising abruptly before, then increasing evenly towards dorsal-fin origin, from there, to caudal-fin base decreasing gradually. Lower surface of head straight and oblique; ventral profile of body from pectoral-fin insertion to anal-fin origin slightly concave, oblique along anal-fin base and straight in caudal peduncle. Head moderately depressed, slightly longer than wide and wider than high, with slightly broad and convex interorbital space. Snout slightly rounded in dorsal view. Eyes small, dorsolateral in posterior half of head. Anterior and posterior nostrils separated and short flap on anterior ones. Mouth small, inferior and arched. Rostral fold divided into three triangular-shaped lobules, median one slightly wider than two lateral ones; tips of these lobules in barbel-like form, but not modified into secondary rostral barbels (Fig. 2 ). One pair of maxillary barbels at corners of mouth; two pairs of rostral barbels in deep groove present between rostral fold and upper lip. Upper lip pendulous and connected with lower lip around corners of mouth by papillated flap; lower lip with four large papillae, two median ones more anteriorly placed and usually larger than the two lateral ones; postlabial groove short and restricted only to mouth corner. Upper and lower jaws bearing thick, with flexible horny sheaths on flanks. Gill opening reaching ventral surface of head, with its upper extremity reaching the level of the middle of the orbit. Body scaled, but absent on head; scales minute, lateral-line complete with 78-90 perforated scales. Anus placed significantly nearer anal-fin origin than pelvic-fin origin.

Dorsal fin with 3 unbranched and 7-8 branched rays, nearly as long as head; dorsal-fin origin almost located halfway between caudal-fin base and snout tip; distal margin slightly concave. Pectoral fin with 1 unbranched and 13-14 branched rays, longer than head; inserted slightly behind lower extremity of gill-opening; tip of adpressed rays not reaching pelvic-fin insertion; distal margin convex. Pelvic fin with 1 unbranched and 8 branched rays, inserted slightly closer to caudal-fin base than to snout tip or midway between pectoral-fin insertion and anal-fin origin or slightly moved backwards; tip of adpressed rays surpassing anus, but far from anal-fin origin; distal margin pointed; axillary lobe present at pelvic-fin base. Anal fin with 2 unbranched and 5 branched rays, last one split to base; origin closer to caudal-fin base than to pelvic-fin insertion; distal margin convex. Anus positioned closer to anal-fin origin than to posterior end of pelvic-fin base. Anal fin extending beyond ventral origin of caudal-fin procurrent rays. Caudal fin slightly forked with lower lobe slightly longer than upper one.

Coloration

In alcohol-stored specimens, top of head with numerous, small, irregular, black bars and blotches; yellowish on ventral surface of head and abdomen. Body with 7-9 dorsal dark black saddles. Last predorsal, subdorsal and first postdorsal saddles wider than all others. Postdorsal saddles wider than interspaces. A number of irregular black blotches on flank above lateral line, nearly connected with dorsal saddles. These black blotches extended downwards to ventral surface of body. Blotch through pelvic-fin insertion extended downwards to base of axillary lobe at pelvic-fin base. A black spot on caudal-fin base, darker than markings on flank. Dorsal fin with 3 black bands across rays. Anal fin with 1 black band. Pectoral fin with 3 irregular faint black bands across rays. Pelvic fin with up to 3 black bands. Caudal fin with 4 black bands.

Diagnosis

Vanmanenia marmorata resembles the four species ( V. caldwelli , V. maculata , V. intermedia and V. stenosoma ) in having three triangular-shaped rostral lobules whose apical portions are in the barbel-like form, but not modified into secondary rostral barbels. It is distinct from these species in having postdorsal dark black saddles wider (vs. narrower) than their interspaces, further from V. caldwelli in having no longitudinal black stripe extending from the snout tip to the caudal-fin base along the lateral line on flank (vs. present) and a more backwards-placed anus [the vent to anal distance 30.5-36.9% (mean 34.6) vs. 60.0-70.3% (mean 68.5) of the pelvic to anal distance]; from V. maculata in having a dark black vermiculated mark (vs. large brown blotch; see Yi et al. 2014: Page 90, fig. 2) on the submargin of the gill cover and a more backwards-positioned anus [the vent to anal distance 30.5-36.9% (average 34.6) vs. 36.4-48.4% (average 43.0) of the pelvic to anal distance] (see Table 3 ); and from V. intermedia in having a larger gill opening with its upper extremity reaching the level of the middle of the orbit (vs. smaller, closer to the level of the lower margin of the orbit; see Deng and Zhang 2020: Page 117: fig. 2), a shorter (vs. longer) anal-fin base [length 5.6-6.4 (mean 6.0) vs. 7.5-9.5 (mean 8.3) % of SL) and a longer (vs. shorter) caudal peduncle [length 11.6-12.9 (average 12.0) vs. 8.4-11.1 (average 9.9) % of SL]; and from V. stenosoma in having a longer (vs. shorter) caudal peduncle [length 11.6-12.9 (mean 12.0) vs. 9.0-11.1 (mean 10.0) % of SL] and a more forwards-positioned pelvic fin [prepelvic length 51.1-53.4 (mean 51.7) vs. 54.7-59.2 (mean 57.2) % SL].

Etymology

The specific epithet is from the Latin word marmor referring to the unique body colouration of irregular marbled markings.

Distribution

This new species is presently known from the upper reaches of the Chen-Shui, a stream tributary to the Yuan-Jiang of the Dongting Lake system in the middle Chang-Jiang Basin, at Jiangkou County, Guizhou Province, south China (Fig. 3 ). It inhabits fast-flowing waters with a gravelly and pebbly substrate (Fig. 4 ). Co-existing species are Discogobio yunnanensis (Regan, 1907), Onychostoma barbatum (Lin, 1931) and Rhinogobius cliffordpopei (Nichols, 1925).

Figures

Figure 1. Vanmanenia marmorata, IHB 2017060069, holotype, 68.8 mm SL; Guizhou Province: Jiangkou County. Lateral (a), dorsal (b) and ventral (c) views of body.

Figure 2. Ventral view of mouth of Vanmanenia marmorata. IHB 2017060069, holotype, 68.8 mm SL; Guizhou Province: Jiangkou County. lj: lower jaw; mb: maxillary barbel; rb: rostral barbel; rf: rostral fold; uj: upper jaw; ul: upper lip; ll: lower lip.

Figure 3. Map showing collection localities of 11 species of Vanmanenia involved in molecular biology studies. The names of rivers and lakes are italicised and two cities (Wuhan and Tongren) highlighted.

Figure 4. Locality of Vanmanenia marmorata, Jiangkou County, Guizhou Province.