Gonorhynchus wattanah, McClelland, 1838

Ciccotto, Patrick J. & Page, Lawrence M., 2016, Revised diagnosis of the genus Gonorhynchus McClelland (Teleostei: Cyprinidae: Labeonini) with redescription of G. latius (Hamilton) and revalidation of G. wattanah (Sykes), Zootaxa 4127 (3), pp. 471-492 : 484-487

Revised Description of Gonorhynchus wattanah

Deccan Latia

( Figures 8 , 11 )

Chondrostoma wattanah Sykes 1839:160 , pl. 63, fig. 4 (type locality: India: Deccan: Beema [Bhima] River); no types known

Chondrostoma wattanah from the Bhima River on the Deccan Plateau was briefly described by Sykes (1839a), with the same short description appearing again in Sykes (1839b). A slightly more complete description, as well as an illustration of a specimen ( Fig. 8 ), were provided two years later ( Sykes 1841). Sykes (1841) indicated that C. wattanah is similar to the ‘ Garra ’ division of cyprinids of Hamilton (1822), which included Gonorhynchus latius . Day (1876) initially speculated that the specimen illustrated in Sykes (1841) may represent Garra lamta ( Hamilton 1822) , but subsequently synonymized C. wattanah with G. latius ( Day 1877) , presumably based on the description and illustration provided by Sykes (1841) as there are no records of Sykes having preserved material from his expedition ( Kottelat 1996; Knight et al. 2014). Our comparison of the illustration with more recently collected specimens from the Bhima River suggest C. wattanah is a member of Gonorhynchus , consistent with previous publications ( Day 1877, 1878; Menon 1999), although curiously the specimen(s) described by Sykes lacked “tendrils” [= barbels] ( Sykes 1839a; 1839b; 1841). Other species that are known to possess barbels, such as Garra mullya (Sykes 1839) , were also reported to lack barbels by Sykes (1839a; 1839b; 1841). It seems likely that Sykes missed these characters during his descriptions.

An examination of specimens that are identified as Gonorhynchus from the Bhima River were found to be morphologically distinct from G. latius and all other Gonorhynchus species. We consider these specimens to represent the species described as C. wattanah by Sykes (1839a, 1839b, 1841) based on similarities in meristics, body shape, and coloration (specifically the thin, dashed stripe along the lateral line). In his initial description, Sykes (1839a) stated that the names of new species, unless otherwise noted, were derived from the names used by the local people of Maharashtra, including C. wattanah (therein capitalized as C. Wattanah ). We propose the common name Deccan Latia , in reference to the distribution of the species on the Deccan Plateau.

Diagnosis. A member of Gonorhynchus as diagnosed above. Gonorhynchus wattanah is differentiated from its congeners by the following combination of characters: absence of rostral flaps on tip of snout (vs. present in G. bicornis ); larger specimens (> 65 mm SL) with small tubercles present all over head, occasionally extending onto the humeral, breast, and predorsal regions (vs. absent in all other species except G. periyarensis where tubercles are only present on the snout and cheek), and 20–24 rakers on the first gill arch (vs. 15–17 in G. p e r i ya re n s i s); thick midlateral stripe absent (vs. present in G. burmanicus ). Cheek height in G. wattanah is generally larger (mean 26.0, range 21.2–29.8 % HL) than in G. latius (mean 18.9, range 14.4–24.6 % HL) and G. diplochilus (mean 19.7, range 12.7–22.8 % HL). Compared to G. latius , G. wattanah possesses modally fewer circumpeduncular scales (16 vs. 20), scales between the anus and anal-fin insertion (4½ vs. 6), and lateral-line scales (34 vs. 37).

Description. Morphometric and meristic data presented in Table 4 . Body slightly arched dorsally, deepest at dorsal-fin insertion. Ventral profile from tip of snout to anal fin flat to slightly concave. Snout conical, rounded at end. Head short, longer than wide. Eyes dorsolateral. Dorsal-fin origin anterior of pelvic-fin origin. Pectoral fin reaching approximately halfway between pectoral-fin insertion and pelvic-fin origin. Pelvic fin to or slightly beyond anus. Anal fin not reaching base of caudal fin. Axillary pelvic lobe well-developed. Caudal fin forked.

Body entirely scaled; scales large. Lateral-line scales and pored scales on caudal fin 34–35 + 2–3 (mode 34 + 2), predorsal scales 9–10, scale rows above lateral line 4½, scale rows below lateral line 4½, circumpeduncular scales 16, 3½ scales rows between lateral line and pelvic-fin origin, 3½–4½ scales between anus and anal-fin origin (mode 4). Dorsal fin with 3 simple and 8½ branched rays; anal fin with 3 simple and 5½ branched rays; pelvic fin with 1 simple and 8 branched rays; pectoral fin with 1 simple and 14 branched rays; caudal fin with 10+9 principal rays, 9+8 branched). Abdominal vertebrae 23–24, caudal vertebrae 11–12, total vertebrae 35–36. Rakers on first gill arch 20–24 (based on 5 specimens from ANSP 85003 [n=1] and CAS-SU 41130 [n=4]).

Rostral cap covering upper lip which is not visibly separated from snout by groove and not attached to lower lip; rostral cap with 17–19 fimbriae superficial to upper jaw. Mouth inferior; upper lip very thin or absent, widening substantially at corner of mouth connecting upper jaw to lower; lower lip free only on anterior and lateral edges, posterior edge connected to underside of head (not modified into rounded mental disc), central region equally thick as lateral edges, anterior edge with large papillae; sublachrymal groove uniformly narrow from corner of mouth to rostral barbel, not expanding anteriorly to contain rostral lobe. Rostral barbels shorter than eye diameter; maxillary barbels present in 8 out of 9 specimens examined; when present, tiny, sometimes hidden in corner of mouth. Small tubercles on all surfaces of head in larger specimens, extending onto back, breast and/or flanks in largest specimens.

Color in 75% Ethanol. Dorsally light to dark brown. Flanks and lateral portions of head mottled dark brown, with irregular clusters of brown spots. Dark pigment around pores of lateral line, producing very thin dashed stripe in larger specimens. Venter cream to yellow. Dorsal-fin and pectoral-fins rays with dark stippling; inter-radial membranes otherwise clear. Anal fin and pelvic fins clear. Small, isolated dark spots on caudal fin, particularly in middle portion. Smaller specimens (43 mm SL and less) substantially less dusky; thin stripe around pores on lateral line present on anterior one-third of flank behind operculum.

Remarks. In Figure 9 , the minimum polygon clusters formed by plotting the second sheared principal component of the morphometric data against the first principal component of the meristic data for populations of G. latius and G. wattanah were compared. Size accounted for 93.7% of the observed variance and the second principal component accounted for 2.0%. Cheek height had the highest loading on the sheared second principal component (-0.63). The first principal component of the meristic data accounted for 60.0% of the total variance. Variables with the highest loadings were total lateral-line scales (0.41), lateral-line scales (0.38), scale rows above lateral line (0.37), and scale rows between the pelvic-fin origin and lateral line. Gonorhynchus wattanah has a greater cheek height (mean 26.0, range 21.2–29.8 % HL) than G. latius (mean 18.9, range 14.4–24.6% HL). Scale counts in G. wattanah in general are lower than those of G. latius ( Tables 2–4 ).

The specimens from the Godavari River are smaller than the Bhima River specimens and lack tubercles. Due to the similarity in body shape and meristic values ( Fig. 9 ), and the occurrence in geographically close river basins, we consider the Godavari River population to be conspecific with the Bhima River populations, with these specimens likely representing sexually immature individuals. The southernmost distribution of G. latius is thus the Mahanadi River ( Fig. 6 ). Specimens from the Mahanadi River are similar to G. latius from the Ganges, Brahmaputra, Surma, and Hooghly Rivers (all outflow into the Bay of Bengal at or near the Ganges Delta) in morphometrics, meristics, and pigmentation ( Fig. 9 , Tables 2–3 ).

Distribution. The species is distributed in the Krishna and Godavari River basins in western India ( Fig. 10 ). Jadhav et al. (2011), Karat et al. (2012), and Laxmappa et al. (2015) report “ Crossocheilus cf. latius ” and “ Crossocheilus latius ” in other stretches of the Krishna River basin; presumably these were specimens of G. wattanah .

Neotype Designation. There is no mention of type material in Sykes (1839a). In the more thorough description by Sykes (1841), an illustration is presented, presumably of one of the original specimens examined ( Fig. 8 ), but again no type (s) are mentioned. An examination of museum records suggests that the material examined by Sykes is lost. While the illustration is available to designate as a lectotype (Article 74.4; ICZN 1999), we designate a neotype in accordance with Article 75 of the Code ( ICZN 1999) in light of the historical confusion of this (and other) species in the genus and the presence of diagnostic characters in the neotype that are not evident in the illustrated specimen. Although tubercles are noted to be absent in this species by Sykes (1839a, 1839b, 1841), they are present in recently examined material and are an important diagnostic feature of the species. It seems likely that Sykes based his descriptions on females and/or sexually immature males. The following specimen is selected as the neotype: ANSP 85003, received from the Indian Museum and collected at the right bank of the canal below the Empress Garden in Pune, India ( Fig. 11 ). This specimen is from the Bhima River basin, near the type locality of Chondrostoma wattanah (Paragon, downstream of confluence of Bhima River and the Mula Mutha River), and possesses the characters diagnostic of G. wattanah ( Table 4 ).

Figures

FIGURE 6. Georeferenced distribution of Gonorhynchus latius in eastern India and neighboring countries (inset). Grey square denotes the locality of the neotype. The locality of the Kangasabati River population was arbitrarily selected due to lack of detail on location of only available specimen (BMNH 1867.5.12.15).

FIGURE 8. Original drawing of Gonorhynchus wattanah from Sykes (1841). Image from the Biodiversity Heritage Library (www. biodiversitylibrary. org); digitized by the Natural History Museum Library, London.

FIGURE 9. Plot of the first principal component of the meristic data (PC 1) and the sheared second principal component (PC 2) of Gonorhynchus wattanah from the Bhima (♦) and Godavari (◊) Rivers basins and G. latius. Filled circle (●) represents specimen from Surma River basin, open square (□) represents specimen from Hooghly River basin, open circles (○) represent specimens from the Ganges-Brahmaputra River basins, and filled triangles (▲) represent specimens from the Mahanadi River.

FIGURE 10. Distribution of specimens of Gonorhynchus wattanah examined from western India (inset). Grey square denotes the locality of the neotype.

FIGURE 11. (A) Dorsal, lateral, and ventral views of the neotype of Gonorhynchus wattanah, ANSP 85003, 86.7 mm SL, Right bank of the canal, below Empress Garden, Pune, India; (B) Lateral view of head, enlarged.

Tables

TABLE 4. Morphometric and meristic values of Gonorhynchus wattanah from the Bhima and Godavari River basins. Data include the neotype.

MORPHOMETRICS
	Neotype	Mean	Range
Standard length (mm)	86.7	58.2	31.9–86.7
% Standard length
Predorsal length	45.6	46.3	44.8–48.7
Preanal length	78.8	78.4	76.5–80.5
Prepelvic length	52.0	52.8	51.3–56.1
Head length	19.7	20.5	19.1–22.5
Body depth at dorsal fin	20.9	21.6	18.8–25.2
Caudal-peduncle depth	11.6	10.8	9.4–11.9
Caudal-peduncle length	13.5	14.5	12.8–15.8
Dorsal-fin base length	16.9	16.1	14.8–17.8
Anal-fin base length	8.0	7.0	5.5–8.0
Pelvic-fin length	21.3	19.7	17.0–21.9
Pectoral-fin length	21.2	20.7	17.4–22.4
% Head Length
Head depth	81.2	76.8	70.2–81.2
Head width	76.3	67.5	59.0–76.3
Snout length	38.5	34.7	28.8–38.5
Orbit diameter	26.9	31.5	26.9–37.6
Interorbital width	44.8	39.5	34.3–44.8
Mouth width	37.6	36.9	32.4–40.3
Width between rostral barbels	26.4	23.3	19.0–27.7
Postorbital length	37.4	34.6	31.0–40.1
Cheek height	29.8	26.0	21.2–29.8
Internarial width	27.4	25.6	23.6–29.5
MERISTICS
		Mode	Range
Pectoral-fin rays	14	14	14
Lateral-line scales	35	34	34–35
Pored scales posterior to lateral line	3	2	2–3
Predorsal scales	10	9,10	9–10
Scales between dorsal-fin origin and lateral line	4½	4½	4½
Scales between anal-fin origin and lateral line	4½	4½	4½
Scales between pelvic-fin origin and lateral line	3½	3½	3½
Scales between anus and anal-fin origin	4	4	4–4½