Vanmanenia orcicampus
Creators: name: Kottelat, Maurice
Publisher: name: Zenodo
Year: 2017
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Actinopterygii
Cypriniformes
Balitoridae
Vanmanenia
Vanmanenia orcicampus

description: <i>Vanmanenia orcicampus</i> &amp;imath; new species (Figs. 1-2) <b>Holotype.</b> MHNG 2767.094 &amp;imath; 47.5 mm SL; Laos: Xiangkhouang Province: Nam Ngum at Ban Khangviang&amp;imath; 19°34'47"N 103°17'42"E&amp;imath; 1138 m asl; M. Kottelat&amp;imath; T. Phommavong &amp; B. L. Amath&amp;imath; 2 March 2012. <b>Paratypes.</b> CMK 22732 &amp;imath; 5 &amp;imath; 20.6-23.2 mm SL; collected with the holotype. <b>Diagnosis.</b> <i>Vanmanenia orcicampus</i> is distinguished from the other species of the genus by its unique colour pattern&amp;imath; made of a midlateral row of six blotches&amp;imath; anterior two longitudinally elongated&amp;imath; 3rd to 5th roundish&amp;imath; 6th faint&amp;imath; at posterior extremity of caudal peduncle; a middorsal row of three predorsal and three postdorsal saddles&amp;imath; 3rd predorsal one extending backwards along dorsalfin base; and vermiculations between saddles and blotches and on lower half of flank. It is further distinguished from congeners in having a slender caudal peduncle whose depth is 1.5 times in its length and 2.5 times in body depth; and 12-14 branched pectoral-fin rays. <b>a b Description.</b> Based on holotype only. See Figures 1-2 for general appearance and Table 1 for morphometric data of holotype. A moderately elongate Gastromyzontidae with arched dorsal profile&amp;imath; body depth regularly increasing up to slightly in front of dorsal-fin origin&amp;imath; decreasing under dorsal-fin base. Behind dorsal fin&amp;imath; body depth decreasing regularly to slightly in front of caudal-fin base. Dorsal profile continuous between head and body. Ventral profile slightly convex. Preventral part of belly and lower surface of head flat. Head slightly depressed; body slightly compressed. Interorbital area flat. In lateral view&amp;imath; eye flushed with dorsal profile of head. Snout rounded. Depth of caudal peduncle 1.5 times in its length&amp;imath; tapering posteriorly&amp;imath; and 2.5 times in body depth. Largest recorded size 47.5 mm SL. Dorsal fin with 4 unbranched and 7 (2) or 7 <b>1</b> / <b>2</b> (4*) branched rays; distal margin almost straight; 1 st and 2nd branched rays longest. Pectoral fin with 1 unbranched and 12 (2) or 13 (4*) branched rays (including small last ray&amp;imath; unbranched)&amp;imath; rounded&amp;imath; reaching <b>3</b> / <b>4</b> of distance to pelvic-fin base. No axillary pectoral lobe. Pelvic fin with 1 unbranched and 8 (4) or 9 (2*) branched rays (including small last ray&amp;imath; unbranched); reaching about ¾ of distance to anus; rounded; origin below base of branched dorsal-fin rays 2-3; axillary lobe present&amp;imath; free&amp;imath; extending on 1 st and 2nd branched rays. Anus situated at about <b>1</b> / <b>3</b> of distance between pelvic-fin base and anal-fin origin. Anal fin with 3 unbranched and 5 <b>1</b> / <b>2</b> (6*) branched rays; distal margin convex. Caudal fin with 7+ 7 (6*) branched rays; about 6 dorsal and about 4 ventral procurrent rays; forked&amp;imath; lobes rounded&amp;imath; of equal length. Upper 4 and lower 4 principal caudal-fin rays adnate (without membranes) until about first branching point. Body entirely covered by scales&amp;imath; except on belly in front of anus. Most scales with an acuminate projection on posterior margin&amp;imath; tip often fleshy&amp;imath; sometimes appearing as ‘soft tubercles’. Lateral line complete&amp;imath; not extending on caudal-fin base&amp;imath; with 79 pored scales. Anterior nostril pierced in front side of a pointed flap-like tube. Posterior nostril adjacent to anterior one. Mouth arched&amp;imath; gape about 2 times wider than long (Fig. 3 b). Two pairs of rostral barbels and one barbel at each corner of mouth. Rostral groove shallow between rostral barbels&amp;imath; deeper from base of outer rostral barbel backwards; edge of rostral fold with three fleshy lobes between rostral barbels. Lips very finely papillated&amp;imath; continuous around corner of mouth. Upper lip fleshy&amp;imath; appearing as three transverse layers: two fleshly layers and a narrow intermediate one&amp;imath; smooth&amp;imath; harder&amp;imath; slightly protruding&amp;imath; not reaching corner of mouth. Lower lip in three parts&amp;imath; each about of equal length&amp;imath; separated by small notches; median part thin&amp;imath; papillated along anterior edge; lateral parts thick and fleshy&amp;imath; with a small projection at midlength; postlabial groove restricted to behind lateral parts. Mouth structure of juvenile (Fig. 3 a- b) as adult&amp;imath; except that mouth is narrower&amp;imath; lower jaw exposed. Notches between three parts of lower lip not very marked; lateral parts close together&amp;imath; more or less in contact mesially&amp;imath; where fleshier and with two short projections and in some individuals forming a ridge with contralateral&amp;imath; wide and thin towards maxillary barbel with a short projection along median edge. Gill opening extending downwards in front and below base of anterior pectoral-fin ray. Tubercles on all surfaces of head&amp;imath; finer on snout and top of head&amp;imath; larger but smooth on ventral surface&amp;imath; large and densely set on opercle. Unculiferous pads (sensu Conway et al. &amp;imath; 2012): in pectoral fin&amp;imath; well developed along anterior edge of unbranched ray and behind unbranched and first seven branched rays&amp;imath; hardly distinct on remaining branched rays; in pelvic fin&amp;imath; well developed along anterior edge of unbranched ray and behind unbranched and first three branched rays. <b>Coloration.</b> After about one month in formalin. Adult: Head and body background colour pale yellowish brown&amp;imath; throat&amp;imath; belly&amp;imath; lower part of caudal peduncle whitish; except otherwise stated&amp;imath; markings dark brown. Head with a dark blotch in interorbital area and on posterior part of head; snout&amp;imath; suborbital area and opercle variegated. Body with three predorsal and three postdorsal saddles; third predorsal saddle extending backwards along (but not touching) dorsal-fin base; saddles restricted to middorsal area&amp;imath; not extending down side. A midlateral row of six blotches&amp;imath; anterior two longitudinally elongated; 3rd to 5th roundish; 6th faint&amp;imath; at posterior extremity of caudal peduncle. Vermiculations between rows of saddles and blotches and on lower half of flank&amp;imath; paler brown than saddles and blotches. A blackish band between posterior extremity of second blotch&amp;imath; connecting it with its contralateral across base of dorsal fin. Dorsal fin hyaline&amp;imath; with two irregular rows of spots&amp;imath; most located on rays and membranes between branches at level of 1 st and 2nd branching points (and at similar position on last unbranched ray). Caudal fin hyaline&amp;imath; with three vertical rows of spots&amp;imath; first one near base of rays&amp;imath; second and third one on rays and membranes between branches near branching points; spots on first row appearing as a blotch on lower and upper most rays (not separated by membranes at this position). Anal fin hyaline&amp;imath; with an elongated mark on rays&amp;imath; mainly near branching points. Pelvic fin hyaline&amp;imath; with two irregular rows of spots&amp;imath; one in proximal position on posterior rays&amp;imath; one on rays and membranes between branches near branching points. Pectoral fin hyaline&amp;imath; with three irregular rows of spots&amp;imath; one in proximal position on posterior rays&amp;imath; one on rays and membranes between branches near branching points of all rays (faint on posterior rays)&amp;imath; and one in similar position but absent on posterior rays. Juveniles: Body background colour yellowish white&amp;imath; marking dark brown. Four juveniles (Fig. 2 a) with three large blotches along lateral line&amp;imath; connected by a broad band over lateral line. First blotch connected with contralateral across back by a band of paler brown pigments&amp;imath; in position of second saddle in adult. Second and third blotches connected with contralaterals across back by band of similar pigments&amp;imath; in position&amp;imath; respectively&amp;imath; of blackish band across dorsal-fin base and of 5th saddle in adult. Blotches and transverse bands resulting in four elliptic pale areas (anterior one not sharply contrasted)&amp;imath; with a patch of pale brown pigments in centre of each&amp;imath; in position of 1st&amp;imath; 3rd&amp;imath; 4th and 6th saddles in adult. A conspicuous black blotch on proximal <b>1</b> / <b>3</b> of dorsal fin. In largest juvenile (Fig. 2 b; only 3 mm longer than smallest)&amp;imath; pattern still distinct&amp;imath; but blotches smaller&amp;imath; restricted to along lateral line and forming a very irregular stripe. Blotch on caudal fin fainter. <b>Distribution and habitat.</b> <i>Vanmanenia orcicampus</i> has been collected only once in the upper Nam Ngum at the northern edge of the Plain of Jars. The Nam Ngum crosses the western part of the plain before descending westwards through 110-km long gorges until the Nam Ngum 2 reservoir and then to the Mekong. It was not present in the other 44 sites sampled in the Nam Ngum watershed downstream of the plain. The plain is also drained to the south by the Nam Ngiep (another Mekong tributary) and the Nam Neun&amp;imath; which flows to Vietnam (as Song Lam) and reaches the Gulf of Tonkin. It is possibly present in the Nam Ngiep and Nam Neun on the plain but sites with an appropriate topography could not be sampled. It was not present at 33 sites in the Nam Ngiep watershed (a Mekong tributary) and 11 sites in the Nam Neun drainage (which flows directly to the Gulf of Tonkin) downstream of the plain. At the type locality&amp;imath; the Nam Ngum was a sluggish stream in an open agricultural area (Fig. 4). The bottom was made of sand to cobble&amp;imath; at places covered by mud. The current was slow. This is unlikely to be the original habitat&amp;imath; which was probably pebble to stone bottom. The juveniles were caught among gravel and pebble. The adult was obtained among bamboos used to build a weir. The other species present were a mix of species usually found in streams with fast current and clear water (<i>Devario</i> cf. <i>laoensis</i> &amp;imath; <i>Poropuntius angustus</i> &amp;imath; <i>Scaphiodonichthys acanthopterus</i> &amp;imath; <i>Schistura defectiva</i> &amp;imath; <i>S. quaesita</i> &amp;imath; <i>Rhinogobius milleri</i>) and species typical of sluggish waters and swamps (<i>Puntius brevis</i> &amp;imath; <i>Systomus jacobusboehlkei</i> &amp;imath; <i>Channa gachua</i> &amp;imath; <i>Macropodus opercularis</i>). <b>Etymology.</b> From the Latin nouns orca (jar; dative plural: orcis) and campus (plain&amp;imath; field)&amp;imath; literally the plain with the jars&amp;imath; reference to the type locality on the Plain of Jars. A compound noun in apposition.
description: Published as part of <i>Maurice Kottelat, 2017, Vanmanenia orcicampus ı a new species of loach from the Plain of Jarsı Laos (Teleostei: Gastromyzontidae), pp. 87-95 in Ichthyol. Explor. Freshwaters 28 (1)</i> on pages 88-91, DOI: 10.5281/zenodo.886193