Parambassis waikhomi , a new species of glassfish ( Teleostei : Ambassidae ) from Loktak Lake , northeastern India

Journal of Threatened Taxa | www.threatenedtaxa.org | November 2012 | 4(14): 3327–3332 3327 Abstract: Parambassis waikhomi, a new species of glassfish from Loktak Lake, Chindwin basin in Manipur, northeastern India is distinguished from its congeners by the presence of 58–60 lateral line scales; two predorsal bones; a vertically elongated humeral spot; 24 vertebrae; maxilla reaching to 1⁄3 of the orbit; 8.210.9 interorbital width; four preorbital ridge, 11 preorbital edge, six supraorbital ridge, 18 serrae at lower edge of preoperculum, 24 serrae at hind margin of preoperculum. The species differs from its nearest congener P. ranga by the presence of 9–10 (vs. 12–13) pectoral fin rays and 19–20 (vs. 22–28) gill rakers.


Materials and Methods
Measurements were made point to point with dial calipers to the nearest 0.1mm and expressed as percentages of standard length (SL).Counts and measurements were made on the left side of specimens under a PC-based binocular stereozoom microscope (Olympus SZ40) with transmitted light.Methods for counts and measurements follow Kottelat (2003).Terminology for cephalic serration follows Fraser-Brunner (1955).Clearing and staining of specimens for osteology followed Hollister (1934).Identification and nomenclature of bones and vertebral counts followed Greenwood (1976) Paratypes: 16 ex., 31.5-39.8mm SL; same collection data as holotype (RCMMF-2-17).3 ex., 34.2-36.3mm SL; dissected, cleared and stained for osteology .
Body covered by scales, except in predorsal area.Head naked, except 3-4 (4) scale rows on cheek.Lateral-line scales 58-60; 10 rows of scales between lateral line and base of last dorsal spine; ½ 9/1/9 ½ scale rows in transverse line across caudal peduncle.First dorsal fin with seven spines, second one longest; second dorsal fin continuous with first with one spine and 14-15 (14) branched rays (last two rays inserted on same pterygiophore counted as one).Anal fin with three spines, third one longest, with 14-15 (14) branched rays.Pelvic fin with one spine and five branched rays.Pectoral fin with 10 rays.Caudal fin with 11+11 branched rays, vertebrae 24 (3).Dentition: Many small conical teeth are embedded in the premaxilla where the teeth in the outer row is larger.Dentary is also with many small villiform teeth where 5-6 canine-like teeth are randomly arranged medially on each side (Fig. 2).
Coloration: In 10% formalin: head and body background creamish.A faint blackish axial streak on body, darker posteriorly.Each scale margins outlined by indistinct melanophores.A vertically elongated humeral blotch, more or less continuing a vertically elongated triangular blotch immediately in  front of first dorsal-fin origin.Second to fourth spine of first dorsal with a decorative distinct blackish outer margin, second dorsal hyaline.Pectoral, pelvic and anal fins hyaline.Caudal fin with a series of unevenly distributed dots between each ray.Live colours: Pattern as in preserved specimens, general colouration yellowish to silvery, body semitransparent with yellowish-chin.

Etymology
This new species is named after Prof. Waikhom Vishwanath honouring his contributions to the ichthyology of freshwater fishes of northeastern India.
Parambassis waikhomi sp.nov.differs from P. apogonoides, P. dayi, P. macrolepis, P. siamensis, P. thomasi, and P. wolffii by the presence (vs.absence) of a humeral spot.It differs from P. apogonoides, P. dayi, P. macrolepis, P. siamensis, and P. thomasi, P. wolffii by the absence (vs.presence) of predorsal scales.It is also distinguished from P. apogonoides, P. dayi, P. thomasi, P. wolffii and P. vollmeri in having more scale (58-60 vs. 34-50) in the lateral series.It differs from P. vollmeri in having more gill rakers (19-20 vs. 13-16), and the absence of serrae (vs.presence of 11 serrae) in the preopercular ridge.It also differs from P. bistigmata in the absence (vs.presence) of two distinct black spots on either side of the anal fin origin connected by a narrow black curved line.
The new species is distinguished from P. tennaserimensis in having more scales (58-60 vs. 53) in the lateral series, more serrae in the preorbital edge (11 vs. 5) and more serrae in lower edge of preoperculum (18 vs. 9).It differs from P. pulcinella in (absence vs. presence) of a conspicuous compressed hump in front of first dorsal-fin origin and in having more number of scales in lateral series (58-60 vs. 51-53).
Parambassis baculis and P. ranga were previously included under the genera Pseudambassis (Talwar & Jhingran 1991).Later in 1994, Roberts transferred them as the generic characters fit that of Parambassis.
According to Roberts (1994), Parambassis can be divided into two species groups; one usually without a humeral spot and with short dorsal and anal fins (each with only 9-11 soft rays) and another usually with a humeral spot and with long dorsal and anal fins (each 12-17 soft rays).He felt, however, that these groups were not monophyletic.Parambassis waikhomi sp.nov.apparently belongs to the later group.Some of the glass fishes are widely distributed in different basins.Roberts (1994) stated that glassperches are most numerous in India and Borneo.The widespread nature of occurrence could be attributed either to the ornamental trade and widespread introductions or the 'widespread' species could be species complexes.However, the populations of various species in many basins need examination and verification.