Ghatsa, Randall, Zachary S. & Page, Lawrence M., 2015

Randall, Zachary S. & Page, Lawrence M., 2015, On the paraphyly of Homaloptera (Teleostei: Balitoridae) and description of a new genus of hillstream loaches from the Western Ghats of India, Zootaxa 3926 (1), pp. 57-86 : 79-81

Ghatsa , new genus

( Figures 4 F, 5F, 16)

Remarks. The following five species of balitorines from the Western Ghats of India have been recognized as belonging to the genus Homaloptera ( Randall & Page 2012; Kottelat 2012): H. montana Herre 1945 , H. pillaii Indra & Rema Devi 1981 , H. menoni Shaji & Easa 1995 , H. santhamparaiensis Arunachalam et al. 2002 , and H. silasi Madhusoodana Kurup & Radhakrishnan 2011 . Due to the inaccessibility of specimens from institutions in India, this group has had an unresolved taxonomic status. It has been proposed by Pethiyagoda & Kottelat (1994) [for the first two species listed above], and by Kottelat (1998) [for the first three species listed above] that these species require a new genus or subgenus (Tan & Ng 2005). The only species examined in this study from this Indian assemblage was H. montana (holotype, CAS-SU 39871) ( Fig. 16 ). Homaloptera montana can be distinguished from all species of Homaloptera (sensu lato) by the combined characters of placement of dorsal-fin origin, tiny and smooth scales, truncated caudal fin, and features of the mouth. Based on these characters, H. montana does not belong to any established balitorid genus and the newly created genus, Ghatsa is created for it. The four other species formerly recognized in Homaloptera from the Western Ghats that were unavailable for examination ( H. pillaii Indra & Rema Devi 1981 , H. menoni Shaji & Easa 1995 , H. santhamparaiensis Arunachalam et al. 2002 , and H. silasi Madhusoodana Kurup & Radhakrishnan 2011 ) are tentatively placed in Ghatsa , since they are morphologically (based on type descriptions) more similar to H. montana than to any other balitorine. Further examination of these species is needed.

Type species. Homaloptera montana Herre, 1945:400 .

Diagnosis. Distinguishing characters are given in Table 4 and shown in Figures 4 F, 5F, and 16. Ghatsa is distinguished by the combination of the following characters: dorsal-fin origin posterior to pelvic-fin origin; emarginated-truncated caudal fin; small, smooth scales ( Fig. 4 F) (data only available for G. montana ); 59–ca.101 lateral-line scales, ca. 53 predorsal scales (data only available for G. montana ); anus closer to anal-fin origin than to pelvic-fin insertion; adipose keel on caudal peduncle (data only available for G. montana ); small rostral cap; 2 thin, widely separated rostral barbels; thin, smooth crescentic upper lip; absence of fleshy pad or lobes between lateral portions of lower lip ( Fig. 5 F).

Species. Ghatsa montana ( Herre 1945) . The following species are tentatively recognized in Ghatsa : G. pillaii (Indra & Rema Devi 1981) , G. menoni (Shaji & Easa 1995) , G. santhamparaiensis ( Arunachalam et al. 2002) , and G. silasi ( Madhusoodana Kurup & Radhakrishnan 2011) . Type localities for species in Ghatsa are shown in Figure 17 .

Comparison. Ghatsa is distinguished from Homaloptera by having the dorsal-fin origin posterior vs. anterior to the pelvic-fin origin; scales small and smooth (data only available for G. montana ) vs. medium and keeled; ca. 53 (data only available for G. montana ) vs. 20–27 predorsal scales; truncated or slightly emarginated vs. forked caudal fin; adipose keel present (data only available for G. montana ) vs. absent; small vs. large rostral cap; medial- and lateral-rostral barbels widely separated from one another at base vs. barbels in close proximity to one another; crescentic rather than triangular upper lip; thin vs. thick upper lip; absence vs. presence of fleshy pad between lateral portions of lower lip.

Ghatsa is distinguished from Homalopteroides by having small and smooth scales (data only available for G. montana ) vs. large and wart-like/keeled scales; ca. 53 (data only available for G. montana ) vs. 14–25 predorsal scales; 59–ca. 101 vs. 33–52 lateral-line scales; truncated or slightly emarginated vs. forked caudal fin; and adipose keel present (data only available for G. montana ) vs. absent.

Ghatsa is distinguished from Homalopterula by having thin vs. thick barbels and upper lip; absence vs. presence of fleshy lobes between lateral portions of lower lip; and by 59–ca. 101 vs. 57–75 lateral-line scales.

Ghatsa is distinguished from Balitoropsis and Pseudohomaloptera by having the dorsal-fin origin posterior vs. anterior to pelvic-fin origin; smooth (data only available for G. montana ) vs. keeled scales; ca. 53 (data only available for G. montana ) vs. 13–15 and 13–19 predorsal scales, respectively; slightly emarginated to truncated vs. forked caudal fin; adipose keel present (data only available for G. montana ) vs. absent; small vs. large rostral cap; medial- and lateral-rostral barbels widely separated from one another at base vs. barbels in close proximity to one another; absence vs. presence of a fleshy pad between lateral portions of the lower lip. It is further distinguished from Balitoropsis by having an anus closer to anal-fin origin than to pelvic-fin insertion; 59–ca. 101 vs. 42–55 lateral-line scales.

Etymology. Named for the Western Ghats of India where species of this genus appear to be endemic. Gender feminine.

Figures

FIGURE 4. Scale sizes and keel patterns of predorsal region: Large, and keeled scales, (A) Balitoropsis zollingeri, UF 166094, 52.1 mm SL; (B) Pseudohomaloptera tatereganii, RMNH 7632 (holotype), 64.6 mm SL. Large, and wart-like / keeled scales (C) Homalopteroides wassinkii, UF 183330, 43.6 mm SL. Medium, and keeled scales, (D) Homaloptera cf. ocellata, UF 161718, 64.1 mm SL. Small, and smooth scales, (E) Homalopterula ripleyi, ANSP 188908, 43.1 mm SL; (F) Ghatsa montana, CAS-SU 39871 (holotype), 46.6 mm SL. Scale bar represents 1 mm. Left side of photo is anterior.

FIGURE 5. Oral morphology of (A) Homaloptera cf. ocellata, UF 161718, 64.1 mm SL; (B) Homalopteroides wassinkii, UMMZ 155660, 46.2 mm SL; (C) Homalopterula ripleyi, ANSP 188908, 43.1 mm SL; (D) Balitoropsis zollingeri, UF 166094, 52.1 mm SL; (E) Pseudohomaloptera tatereganii, RMNH 7632 (holotype), 64.6 mm SL; (F) Ghatsa montana, (holotype) CAS- SU 39871, 46.4 mm SL. Abbreviations: CF, central furrow; FL, fleshy lobe; FP, fleshy pad; LJ, lower jaw; LL, lower lip; LRB, lateral-rostral barbel; MB, maxillary barbel; MRB, medial-rostral barbel; RC, rostral cap; UJ, upper jaw; UL, upper lip.

FIGURE 16. Ghatsa montana, CAS-SU 39871 (holotype), 46.4 mm SL. (A) Dorsal, lateral, and ventral views, Puthutotam Estate, brook in Anamallai Hills, India; (B) radiograph. Photos by CAS, Ichthyology Section.

FIGURE 17. Type localities for species of Ghatsa. Asterisk represents the type species of the genus.