Cremnoconchus syhadrensis (W. T. Blanford, 1863)

Reid, David G., Aravind, Neelavara Ananthram & Madhyastha, Neelavara Ananthram, 2013, A unique radiation of marine littorinid snails in the freshwater streams of the Western Ghats of India: the genus Cremnoconchus W. T. Blanford, 1869 (Gastropoda: Littorinidae), Zoological Journal of the Linnean Society 167 (1), pp. 93-135 : 103-116

CREMNOCONCHUS SYHADRENSIS

(W.T. BLANFORD, 1863)

(FIGS 2G, I, 3, 4B, C, 5A, B, 6, 7A, B, 8, 16C)

Cremnobates syhadrensis Blanford, 1863: 184–186 , pl. 4, figs 1–7 (fig. 6, crawling animal; figs 4, 5, operculum) (Western Ghats, in the neighbourhood of Bombay, India; restricted to Khandala by Subba Rao & Mitra, 1979; here corrected to Matheran, Raigad District, Maharashtra; neotype, here designated, BMNH 1906.1.1.2247, Fig. 3A ). Troschel, 1867: 90–94, pl. 2, fig. a (radula).

Cremnoconchus syhadrensis – Blanford, 1869: 343. Stoliczka, 1871: 108–115, figs 1–3 (anatomy), 4, 5 (radula). Hanley & Theobald, 1876: 58, pl. 146, fig. 6. Theobald, 1876: 12. Nevill, 1885: 173. Tryon, 1887: 256, pl. 46, fig. 47. Preston, 1915: 65 (as syhadensis). Annandale & Prashad, 1919: 149, pl. 4, figs 2, 3 (anatomy), 4 (radula) (in part, includes C. canaliculatus ). Prashad, 1925: 138–139, fig. 2C (mantle cavity). Linke, 1935: 72–87, figs 1–8 (anatomy). Reid, 1989: figs 1i, 4c, d (operculum), 6i (penis), 9i (pallial oviduct). Aravind et al., 2011: 58 (unnumbered fig.) (BMNH 1906.1.1.2247, same lot as neotype of C. syhadrensis ).

Cremnoconchus (Cremnoconchus) syhadrensis – Thiele, 1929: 125, fig. 98. Wenz, 1938: 522, fig. 1376. Subba Rao & Mitra, 1979: 24–25. Subba Rao, 1989: 63, figs 88, 89, 89a, b. Ramakrishna & Dey, 2007: 111, fig. 67A, B.

Cremnoconchus ‘ from Mahabaleshwar’ Aravind et al., 2011: 58, unnumbered fig. (locality in error; BMNH 1906.1 .1.2247, same lot as neotype) .

Taxonomic history: No types were segregated in BMNH, but there exists a sample of four specimens from W. T. Blanford’s collection labelled, in his hand, ‘ Cremnobates syhadrensis picked specimens’, but with no locality. One of these is here designated neotype ( Fig. 3A ). The type locality was restricted to Khandala by Subba Rao & Mitra (1979), but this is here corrected to Matheran (see Remarks). The specific name is derived from ‘Sahyadri’ (erroneously spelled ‘Syhadri’ by Blanford, 1863), the name for the Western Ghats in Marathi and other Indian languages.

Diagnosis: Shell turbinate with 2–8 spiral ribs above periphery; pseudumbilicus present or absent; surface dull, with fine or indistinct microstriae. Operculum thickly calcified, with internal ridge. Penis with distal glandular swelling of base, no lateral glandular

flange or drum-shaped gland, stout filament. Western Maharashtra State.

Shell ( Figs 3 , 4B, C ): Shell H 5.0– 9.9 mm. Shape ( Table 1) broadly turbinate; whorls rounded, weakly angled at periphery; suture distinct; apex intact or eroded. Columella moderately broad. Pseudumbilicus usually conspicuous and perforated ( Fig. 3F ), 0.6– 1.2 mm wide, with sharply angled margin; sometimes narrow and not perforated ( Fig. 3H ), 0.1–0.5 mm; may be closed in juveniles. Upper surface: usually 5–10 (mode 8) narrow ribs at and above periphery, sometimes becoming weak on last whorl ( Fig. 3J ); ribs (especially on spire) may be slightly granulated by intersection with growth lines; 0–3 threads in interspaces between grooves; shell sometimes smooth but for narrow rib at shoulder (giving broad sutural ramp and turreted spire profile) and at angled periphery ( Fig. 3L, M ). Base: usually 15–24 threads, becoming finer and ultimately indistinct towards pseudumbilicus ( Fig. 3C ); sometimes 5–10 ribs, of which innermost 2–3 develop as narrow ribs ( Fig. 3E ); base may lack sculpture ( Fig. 3F ). Entire surface dull, covered with fine or indistinct spiral microstriae ( Fig. 4B, C ). Protoconch ( Fig. 16C ) 1.3–1.4 whorls; diameter 0.47– 0.60 mm; diameter of first whorl 0.29–0.45 mm. Colour: pale yellow-brown, often with red-brown spire (shell fading to white with purplish or pinkish spire; Fig. 3A ); some have narrow brown band at suture and broader brown band between shoulder and periphery ( Fig. 3G, I ); base sometimes with broad brown band but paler around umbilicus ( Fig. 3H ); columella white, columella and umbilicus sometimes stained purple-brown ( Fig. 3C ); aperture yellowish with redbrown bands showing through.

Animal: Head, tentacles, and sides of foot pale to dark grey or black; sometimes unpigmented except for grey tentacles and tip of snout (Fig. 2I). Gills: 30–40 leaflets; unpigmented. Operculum ( Table 1; Fig. 5A, B): opercular ratio high, 0.471 –0.600; strongly calcified, with thickened internal ridge. Penis ( Fig. 6A, B, D–G ): unpigmented; base wrinkled, distal 20–60% smooth, swollen, opaque and glandular, invagination 20–40% of length of base in ethanol-fixed specimens; filament relatively stout, usually protruding in ethanol-fixed specimens, tip can be retracted to about half length of penial base in living animals. Pallial oviduct ( Fig. 6C ): as for genus. Pallial oviduct containing 1– 5 eggs 0.24–0.49 mm diameter, including transparent covering 0.06 mm thick (observed alive).

Radula ( Fig. 7A, B ): Relative radula length 1.60–4.24. Rachidian: length/width 1.51–1.57; 5 cusps (+ 1 outer denticle on either side). Lateral: 5 cusps (+ 1 inner denticle). Inner marginal: 5 cusps (+ 1 outer denticle; sometimes + 1 inner denticle). Outer marginal: 3–5 cusps (sometimes + 1 outer denticle). Major cusp of each of 5 central teeth in each row elongate leafshaped with rounded tip; other cusps pointed.

Range ( Fig. 8 ): Western Maharashtra State, from about 30 km west of Nashik to 50 km south-west of Pune (185 km linear distance). Records (Supporting Table S1): Maharashtra State: Anjani, near Trimbakeshwar, Nashik District (BMNH 1907.9.25.3–4); Igatpuri ( Blanford, 1870; as Egutpoora); Matheran (BMNH 20120035; ZSI/WGRS/IR.INV-2290, 2291); Bhor Ghat (BMNH 1868.12.11.38); Khandala (BMNH 1888.12.4.823–826; ZSI/WGRS/IR.INV-2292, 2293); Karlee Hill Fort, Kurkulla, near Pune (locality tentatively identified as Karli; USNM 317697); Vadgaon, near Pune (USNM 317687); Sinhgarh Fort, near Pune (USNM 317691); Torna Fort, near Pune (USNM 317695, 317696, 317683); Rajgarh Fort, near Pune (USNM 317688).

Habitat and ecology: On unshaded east-facing cliff with water seeping over rock; 442 m altitude; common, found individually, with many juveniles (Matheran population; 17 Oct. 2010). On wet basalt cliffs, clustered in tightly packed groups of up to 1000 under overhangs 30 cm in width; 297 m altitude (Khandala population; 17 Oct. 2010; Fig. 2F, G). Hora (1926: 448) recorded it as ‘quite plentiful on big rocks projecting out of the water at the edge of the pool in the neighbourhood of the fall [near Khandala, at end of December]. They were found aestivating in small pits well protected from the midday sun.’ Annandale (1919) also observed it in great abundance on cliffs at Khandala, shaded from the midday sun, where animals were active in spray from the falls, feeding on a ‘dull green filamentous alga’. Stoliczka (1871) noted that the stomach contained ‘minute algae’. Collected from 4000 ft (1219 m) at Anjani (BMNH 1907.9.25.3– 4). Recorded localities range up to 1400 m (Supporting Table S1).

Remarks: This is the most well-known species in the genus and has been the subject of several anatomical studies ( Stoliczka, 1871; Annandale & Prashad, 1919; Prashad, 1925; Linke, 1935; Reid, 1989) and ecological notes ( Stoliczka, 1871; Annandale, 1919; Hora, 1926). It was found to be common at Matheran and extremely abundant at Khandala (October 2010). However, Matheran is a tourist destination where development is proceeding and Khandala lies in the Bhor Ghat Pass, where motorways are under construction to carry heavy traffic between Mumbai and Pune. The future of these sites cannot be regarded as secure. The Matheran site is the only known locality at which Cremnoconchus occurs outside the defined limits of the Western Ghats region ( Fig. 8 ).

Populations of this species show considerable differentiation in shell form across the range. The type locality was given only as ‘in the neighbourhood of Bombay [ Mumbai]’ in the original description by Blanford (1863: 184), but he subsequently recorded it from ‘Khandalla [Khandala] where the first specimens were obtained, but also on Matheran hill and at Egutpoora [Igatpuri]’ ( Blanford, 1870: 11). His description was of a spirally ribbed, umbilicate, white shell with reddish apex. This, and the (unlocalized) collection from which the neotype ( Fig. 3A ) has been selected, correspond most closely with modern samples from Matheran ( Fig. 3B, C ). Differences among available local populations are summarized in Table 2. There is variation in adult size, development of ribs both above and below the periphery, size of umbilicus and colour. In USNM there are three large

› Figure 5. Opercula of Cremnoconchus species. A , B, C. syhadrensis, Matheran, Raigad Dist. , Maharashtra. C, D, C. dwarakii, Hulikal Ghat, Udupi Dist. , Karnataka. E, F, C. conicus , 44 km west of Bhor, Pune Dist., Maharashtra. G, H, C. canaliculatus , 5 km south of Mahabaleshwar, Satara Dist., Maharashtra. I, J, C. hanumani, Hanuman Gundi Falls, Chikmagalur Dist. , Karnataka. K, L, C. globulus, Lesser Kadambi Falls, Chikmagalur Dist. , Karnataka. M, N, C. agumbensis, Agumbe, Udupi Dist. , Karnataka. O, P, C. cingulatus, Hulikal Ghat, Udupi Dist. , Karnataka. Q, R, C. castanea, Arasinagundi Falls, Udupi Dist. , Karnataka. Abbreviation: b, thickened boss on inner surface of operculum of C. syhadrensis (indistinctly visible by SEM because of low relief and therefore indicated with dotted outline).

samples from Torna Fort, near Pune, from the Evezard Collection, made in the late 19th century. These were originally sorted and labelled according to their sculpture: ‘ C. syhadrensis ’ (normal eightribbed shells; USNM 317683), ‘ C. conicus var. canal- iculatus ’ (mostly two ribs, at shoulder and periphery only; USNM 317696); ‘ C. conicus var.’ (two-ribbed shells, but mixed with some C. conicus and C. canaliculatus ; USNM 317695). Intermediate forms link the extremes of eight- and two-ribbed shells ( Fig. 3F, J–M ) and these three samples are suggested to be from a single very variable population. The opercula of the Torna samples are the same as those of specimens from other localities, with strong calcification and a prominent inner ridge, but no anatomical material from Torna was available.

There is also variation in the size of eggs and in the diameter of the first whorl of the protoconch. In a female from Matheran the three eggs in the pallial oviduct ranged from 0.24 to 0.39 mm in diameter and the diameter of the first whorl (N = 3) from 0.29 to 0.39 mm in the few shells with intact apex in the sample. The overall ranges of these parameters in the species were larger still (see description above).

The shell of C. syhadrensis is the most robust of the Cremnoconchus species , being relatively thick and reinforced by spiral ribs, and the operculum is more thickly calcified than in the others. It is not known if this reflects selection by crushing predators or other mechanical forces. The frequency of repaired shell breakages (remaining as scars on the shell) has been used as an index of sublethal predation or damage (e.g. Reid, 1992). In a total of 208 adult shells (of the Matheran and Khandala types; Table 2) in BMNH, 20 (9.6%) showed a major repaired breakage. The cause is not known, but this is a low level of sublethal damage in comparison with that seen in some marine littorinids ( Reid, 1992).

Only in one sample from Torna (USNM 317695) is this species mixed with others, C. conicus and canaliculatus , implying that all three are found there together. There are also separate lots of C. syhadrensis and C. canaliculatus from both Bhor Ghat and Karlee. Annandale & Prashad (1919: 149) remarked that ‘ two types of shells occur in a large series from the cliffs at Khandalla. The commoner of these agrees well with Blanford’s figure [i.e. Blanford, 1863: figs 1–7], but in a few specimens the upper surface of the body-whorl is flattened and grooved much as in the same author’s var. canaliculatus of C. conicus .’ This is interpreted as a reference to C. canaliculatus occurring with C. syhadrensis , although in the present study only C. syhadrensis was encountered at Khandala in the Bhor Ghat Pass. At these localties of likely sympatry the shell characters of each species remain distinct, supporting their separate species status.

The low spire, 2–8 ribs, weak microstriae and strongly calcified operculum are the diagnostic traits of C. syhadrensis (see Table 3 for distinction of the three sympatric species). Confusion is possible with C. canaliculatus , but this never develops a distinct peripheral rib, is sometimes tall-spired, has stronger microstriae and a less thickly calcified operculum.

CREMNOCONCHUS CONICUS W.T. BLANFORD, 1870

(FIGS 2H, 4D, E, 5E, F, 7C, D, 8, 9A–O, 10A–H)

Anculotus carinatus Layard, 1855: 94 (Mahakeshwar Hills [Mahabaleshwar], Bombay Presidency, India; lectotype, here designated, plus 4 paralectotypes BMNH 20120031, Fig. 9D, E; not Anculotus carinatus Anthony 1840 ).

Cremnoconchus carinatus – Blanford, 1869: 343. Blanford, 1870: 11–12, pl. 3, fig. 5. Stoliczka, 1871: 109, 112 (in part, includes C. canaliculatus ). Theobald, 1876: 13. Nevill, 1885: 172. Preston, 1915: 66. Aravind et al., 2011: 58, unnumbered fig. (BMNH 20120031, lectotype of A. carinatus ).

Cremnoconchus (Lissoconchus) carinatus – Subba Rao, 1989: 63, figs 90, 91. Ramakrishna & Dey, 2007: 112, fig. 68A, B.

Anculotus carinatus ‘Anthony’ – Reeve, 1860: Anculotus sp. 42, pl. 5, fig. 42 (not Anthony, 1840; figure is one of the types BMNH 20120031 of A. carinatus Layard, 1855 ).

Cremnoconchus conicus W.T. Blanford, 1870: 10–12 , pl. 3, fig. 3 (Torna, 35 miles W of Poona, India; lectotype, here designated, BMNH 1906.1.1.2239, Fig. 9B; 17 probable paralectotypes BMNH 1906.1.1.2242). Hanley & Theobald, 1876: 58, pl. 146, figs 8, 9. Theobald, 1876: 13. Nevill, 1885: 172. Tryon, 1887: 256, pl. 46, fig. 44 (in part, includes C. canaliculatus ). Preston, 1915: 65–66. Aravind et al., 2011: 58, unnumbered fig. (BMNH 1906.1.1. 2239, lectotype of C. conicus ).

Cremnoconchus (Lissoconchus) conicus – Thiele, 1929: 125. Wenz, 1938: 522, fig. 1377. Subba Rao & Mitra, 1979: 25. Subba Rao, 1989: 64, figs 92, 93. Ramakrishna & Dey, 2007: 112–113, fig. 69A, B.

Cremnoconchus conicus var. edecollata Nevill, 1885: 172 (near Poona; 12 syntypes ZSI, not seen). Tryon, 1887: 256.

Cremnoconchus (Lissoconchus) conicus var. edecollata – Subba Rao & Mitra, 1979: 25–26.

Cremnoconchus carinatus var. gigantea Nevill, 1885: 173 ( Bombay Presidency; 3 syntypes probably in ZSI, not seen). Tryon, 1887: 256.

Taxonomic history: This was the first of the Cremnoconchus species to be discovered, and was originally described as a species of Anculotus (an incorrect subsequent spelling of Anculosa and synonym of Leptoxis , Pleuroceridae ; E. Strong, pers. comm.). This grouping among freshwater cerithioideans is explained by the resemblance of the shell to those of globose pleurocerids, including the North American Leptoxis species. Layard’s name Anculotus carinatus is a junior primary homonym of that of Anthony (1840), introduced for a genuine North American pleurocerid. Owing to the confusion of these homonyms, in his monograph of Anculotus Reeve (1860)

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Character Shell shape ribs Shell Columella Pseudumbilicus Shell surface Operculum Penis

illustrated one of the syntypes of Layard’s species as an example of that of Anthony and gave a North American locality. The shells of the two are not similar.

When Blanford (1870) described the species he considered that its range of variability included shells with a strong shoulder rib, named var. canaliculatus , here shown to be a distinct species. There has been persistent confusion in the taxonomic literature over the names conicus , carinatus , canaliculatus and fairbanki , owing to misguided attempts to classify the two species involved, C. conicus and C. canaliculatus , using shell shape and prominence of spiral ribs. Both these characters are variable within species (see Remarks below).

The shells described by Nevill (1885) as var. edecollata are a sample of the nominal species with intact spires (fide Subba Rao & Mitra, 1979, who examined the syntypes).

Diagnosis: Shell turbinate to tall, lacking ribs; pseudumbilicus absent; surface with satin sheen, microstriae fine or indistinct. Operculum weakly calcified, without internal ridge. Penis with base

› Figure 9. Shells of Cremnoconchus species. A –O, C. conicus . P–EE, C. canaliculatus . A, J, K, Torna Fort, Pune Dist., Maharashtra (BMNH 20120038). B, C. conicus W.T. Blanford, 1870 , lectotype, Torna Fort, Pune Dist., Maharashtra (BMNH 1906.1.1.2239). C, Torna Fort, Pune Dist., Maharashtra (BMNH 1906.1.1.2243; from the same lot as probable paralectotypes of C. canaliculatus ). D, E, Anculotus carinatus Layard, 1855 , lectotype, Mahabaleshwar, Satara Dist., Maharashtra (BMNH 20120031). F–I, Torna Fort, Pune Dist., Maharashtra (USNM 317694). L, M, 6 km west of Mahabaleshwar, Satara Dist., Maharashtra (two views of same specimen; ZSI/WGRS/IR.INV-2295). N, O, 44 km west of Bhor, Pune Dist., Maharashtra (ZSI/WGRS/IR.INV-2296, 2297). P, Q, C. conicus var. canaliculatus W.T. Blanford, 1870 , lectotype, Torna Fort, Pune Dist., Maharashtra (BMNH 1906.1.1.2240). R, C. conicus var. canaliculatus W.T. Blanford, 1870 , probable paralectotype, Torna Fort, Pune Dist., Maharashtra (BMNH 1906.1.1.2243). S, C. fairbanki ‘[W.T.] Blanford’ Hanley & Theobald, 1876, neotype, no locality (BMNH 1906.1.1.2245). T, Mahabaleshwar, Satara Dist., Maharashtra (BMNH 20120039). U, V, Torna Fort, Pune Dist., Maharashtra (USNM 317694). W–Y, Torna Fort, Pune Dist., Maharashtra (USNM 317695). Z, Mahabaleshwar, Satara Dist., Maharashtra (BMNH 20120040). AA, BB, Dongarwadi, Tamhini, Pune Dist., Maharashtra (two views of same specimen; ZSI/WGRS/ IR.INV-2299). CC, DD, Dongarwadi, Tamhini, Pune Dist., Maharashtra (BMNH 20120041). EE, 10 km west of Mahabaleshwar, Raigad Dist., Maharashtra (ZSI/WGRS/ IR.INV-2300).

slightly swollen distally, large basal drum-shaped gland, slender filament. Western Maharashtra State.

Shell ( Figs 4D–E , 9A–O): Shell H 5.0– 12.1 mm. Shape ( Table 1) turbinate to high-turbinate; whorls well rounded, not or only weakly angled at periphery; suture moderately or strongly impressed; apex often eroded. Columella broad. Pseudumbilicus usually absent, or a narrow chink (to 0.2 mm), or a hollowed area up to 1.2 mm wide (never perforated) with sharply angled margin continuous with apertural margin (Fig. 9E). Surface lacks distinct ribs, but a ·

narrow flattened area may be present at suture, which is occasionally bounded by a weak rib (Fig. 9B, G, H). Surface with satin sheen; fine weak microstriae, sometimes obsolete ( Fig. 4D, E ). Diameter of first whorl 0.47 mm (N = 1). Colour: mid-brown, olive brown or golden brown, sometimes with indistinct darker bands, or up to four prominent narrow redbrown bands (at suture, mid whorl, just below periphery and around columella; Fig. 9L, N); columella white or purplish; aperture white to yellow-brown, with purple-brown bands showing through.

Animal: Head, tentacles and sides of foot grey to black, snout sometimes paler (Fig. 2H). Gills: 23–43 leaflets; black or unpigmented. Operculum ( Table 1; Fig. 5E, F): opercular ratio 0.345 –0.423; weakly to moderately calcified, flexible, concave, internal ridge weak or absent. Penis ( Fig. 10A–H): unpigmented; relatively large, base wrinkled, strap-shaped, slightly bulbous distally (sometimes opaque) in ethanol-fixed specimens, with basal opaque cream drum-shaped gland composed of subepithelial lobules; invagination 70–90% of length of base in ethanol-fixed specimens; filament slender, rarely slightly protruding in ethanol-fixed specimens. Pallial oviduct: as for genus.

Radula ( Fig. 7C, D ): Relative radula length 1.13– 2.45. Rachidian: length/width 1.24–1.40; 5 cusps (+1 outer denticle on either side). Lateral: 5 cusps (+ 1 inner denticle). Inner marginal: 5 cusps (+ 1 outer denticle). Outer marginal: 3–5 cusps. Major cusp of each of 5 central teeth elongate leaf-shaped with rounded tip, or elongate triangular and pointed; other cusps pointed.

Range ( Fig. 8 ): Western Maharashtra State, between Karli and Mahabaleshwar (90 km linear distance). Records ( Supporting Table S1): Maharashtra State: Karlee Hill Fort , Kurkulla , near Pune (locality tentatively identified as Karli ; USNM 317693 ); Torna Fort ,

near Pune (BMNH 1906.1.1.2239, 2242, 20120038; USNM 317694, 317696); 44 km W Bhor (ZSI/WGRS/ IR.INV-2296, 2297, 2298); 6 km W Mahabaleshwar (ZSI/WGRS/IR.INV-2295); Mahabaleshwar Hills (BMNH 1871.9.23.149).

Habitat and ecology: On basalt cliffs with algal mat, or bare, covered by flowing water film; on pebbles in shallow pool at foot of cliff with moving water. Collected from 645 m (44 km west of Bhor) and 1103 m (6 km west of Mahabaleshwar). Blanford (1870: 11) recorded that it was ‘met with abundantly on the steep slopes of Torna one of the old Deccan hill forts... The specimens were taken from rocks by the sides of the small torrents running down the hill side.’ His concept of the species included C. canaliculatus . Torna Fort is at an altitude of 1400 m (Supporting Table S1).

Remarks: Like the two other Cremnoconchus species with which it occurs, C. conicus displays shell variation, and this variability and co-occurrence have resulted in taxonomic confusion. Blanford (1870) described, in addition to the typical form, a ‘ var. canaliculatus ’ also from Torna, while considering C. carinatus from Mahabaleshwar to be distinct. He noted: ‘The canaliculate variety serves to connect the typical form with carinatus , as many specimens have the angle at the periphery more marked than in the typical conicus ; but specimens of carinatus are of a somewhat different form, with considerably less swollen whorls. Perhaps all three forms should be considered as varieties of one species, for which, however, the name carinatus , which is not very appropriate even for full grown specimens of the Mahableshwar shell, can scarcely be retained with propriety.’ ( Blanford, 1870: 11). Here it is shown that C. canaliculatus is a distinct species, while C. carinatus is a synonym of C. conicus . Two specimens of C. conicus are present among the probable syntypes of C. canaliculatus . To add to the confusion, C. syhadrensis is also found at Torna, although apparently unknown to Blanford and not present in his material from the site. For example, four large lots from Torna, each of 20–100 dry shells, are present in the Evezard Collection (USNM) made in the late 19th century. Presumably following Blanford’s descriptions, these were originally sorted and labelled according to the presence of spiral ribs: ‘ C. syhadrensis ’ (eight spiral ribs; contains C. syhadrensis alone; USNM 317683); ‘ C. conicus vars’ (variable ribs; contains C. syhadrensis and C. canaliculatus ; USNM 317695); ‘ C. conicus var. canaliculatus ’ (strong rib at suture; contains C. syhadrensis alone; USNM 317696); ‘ C. conicus ’ (no ribs; contains mainly C. conicus with a few C. canaliculatus ; USNM 317694). As discussed below, for each of the three species mixed in these lots the development of ribs and angulation of the whorls are variable. Far more significant for identification are the less readily apparent characters of surface microsculpture and form of the columella and umbilicus (Table 3).

The type series of C. carinatus consists of five large (H up to 9.2 mm) shells of thick texture, turbinate form, with clear but fine microstriae, weakly marked suture, slight peripheral angle (certainly not carinate; the specific epithet is indeed inappropriate, as noted by Blanford, 1870) and wide (but imperforate) pseudumbilical area (Fig. 9D, E). These shells differ from Blanford’s C. conicus (his ‘typical form’; Blanford, 1870), which has a thinner texture, taller spire, indistinct microstriae, impressed suture, rounded whorls, and minute pseudumbilical chink (Fig. 9B). The respective type localities of Mahabaleshwar and Torna are 35 km apart. No specimens exactly resembling Layard’s shells were discovered during fieldwork at Mahabaleshwar in 2010. The stream flowing through the modern town of Mahabaleshwar to the ‘Chinaman Falls’ (Fig. 2D) is now badly polluted; if this was the type locality, Cremnoconchus no longer occur there. However, it may be that the type locality was another of the many small streams in the area, or in the vicinity of the small settlement of Old Mahabaleshwar. Smaller shells (H up to 6.6 mm) were collected 6 km from Mahabaleshwar. These are of thinner texture, with four dark bands and closed pseudumbilicus (Fig. 9L, M). A collection from 44 km west of Bhor, midway between Torna and Mahabaleshwar (Fig. 9N, O), includes specimens that overlap the range of variation at the other two sites, supporting the proposed synonymy.

There is also some variation in the operculum; those of the specimens from near Bhor are thin, flexible, and slightly less tightly coiled (Fig. 5E, F), but those from near Mahabaleshwar are more heavily calcified, appearing more opaque and drying flat ( Table 1).

It is not known whether there is some segregation by microhabitat where C. syhadrensis , C. canaliculatus and C. conicus occur together, as at Torna. Only C. conicus has been found in shallow pools, while both it and C. canaliculatus occur in flowing water, and C. syhadrensis appears to favour damp rocks and shady overhangs. Although C. conicus and C. canaliculatus both occur in the vicinity of Mahabaleshwar, in apparently similar habitats, they were not discovered in the same streams (see Supporting Table S1 for locality details).

Table 3 summarizes the diagnostic characters of the three Cremnoconchus of western Maharashtra. Cremnoconchus conicus can be identified by its satin sheen, wide columella and thin (mainly corneous) operculum. The penial shape of C. syhadrensis is diagnostic, but those of the other two are more similar. Compared with that of C. canaliculatus the penis of C. conicus is relatively larger, has a more swollen apex to the base, and the drum-shaped glandular projection is larger ( Fig. 10).

CREMNOCONCHUS CANALICULATUS W.T.

Figures

Figure 3. Shells of Cremnoconchus syhadrensis. A, Cremnobates syhadrensis W.T. Blanford, 1863, neotype, no locality (BMNH 1906.1.1.2247). B, C, Matheran, Raigad Dist., Maharashtra (two views of same specimen; ZSI/WGRS/IR.INV- 2290). D, E, Anjani, Nashik Dist., Maharashtra (BMNH 1911.8.23.70–71). F, J–L, Torna Fort, Pune Dist., Maharashtra (USNM 317696). G–I, Khandala, Pune Dist., Maharashtra (G, H two views of same specimen; ZSI/WGRS/IR.INV-2293, 2292). M, Torna Fort, Pune Dist., Maharashtra (USNM 317695).

Figure 4. Microsculpture of Cremnoconchus species (viewed by SEM). A, C. dwarakii, Hulikal Ghat, Udupi Dist., Karnataka. B, C. syhadrensis, Matheran, Raigad Dist., Maharashtra. C, C. syhadrensis, Khandala, Pune Dist., Maharashtra. D, C. conicus, 44 km west of Bhor, Pune Dist., Maharashtra. E, C. conicus, 6 km west of Mahabaleshwar, Satara Dist., Maharashtra. F, C. globulus, Lesser Kadambi Falls, Chikmagalur Dist., Karnataka. G, C. cingulatus, Hulikal Ghat, Udupi Dist., Karnataka. H, C. agumbensis, Agumbe, Udupi Dist., Karnataka. I, C. canaliculatus, 10 km west of Mahabaleshwar, Raigad Dist., Maharashtra. J, C. canaliculatus, Dongarwadi, Tamhini, Pune Dist., Maharashtra. K, C. canaliculatus, 5 km south of Mahabaleshwar, Satara Dist., Maharashtra. L, C. castanea, Belkal Thirtha Falls, Udupi Dist., Karnataka. M, C. castanea, Arasinagundi Falls, Udupi Dist., Karnataka. N, C. hanumani, Greater Kadambi Falls, Chikmagalur Dist., Karnataka. O, C. hanumani, Hanuman Gundi Falls, Chikmagalur Dist., Karnataka.

Figure 6. Anatomy of Cremnoconchus syhadrensis. A, B, D–G, penes (A, E–F, fixed in ethanol; B, D, live). E–G are three views of single penis, external (E), with base sectioned (F), and with coiled penial vas deferens displaced to the right to show retractor muscle and with filament sectioned to show continuation of vas deferens to its tip (G). C, pallial oviduct and egg removed from straight section. A, Matheran, Raigad Dist., Maharashtra (BMNH 20120035; shell H = 7.4 mm). B, C, E–G, Matheran, Raigad Dist., Maharashtra (ZSI/WGRS; shell H: B = 7.2 mm; C = 7.2 mm; D = 5.8 mm; E–G = 7.5 mm). D, Khandala, Pune Dist., Maharashtra (ZSI/WGRS). Abbreviations and shading conventions: b, copulatory bursa (dashed outline, visible by transparency); c, cavity surrounding penial vas deferens and retractor muscle (black); d, distal to this point the penial vas deferens is tightly bound to the sheath of the retractor muscle; e.g. egg groove visible by transparency (thick line); f, penial filament; g, opaque glandular region of penial base (medium stipple); gc, firm gelatinous coating of mature egg; i, invagination of penial base (shaded); o, position of terminal opening of pallial oviduct into mantle cavity; oag, opaque part of albumen gland (dense stipple); ov, ovum; pvd, penial vas deferens; rm, retractor muscle of penial filament; ss, straight section of pallial oviduct; tag, translucent region of albumen gland (sparse stipple).

Figure 7. Radulae of Cremnoconchus species (two views of each radula, flat and at 45°). A, B, C. syhadrensis, Matheran, Raigad Dist., Maharashtra (ZSI/WGRS; shell H = 7.0 mm). C, D, C. conicus, 6 km west of Mahabaleshwar, Satara Dist., Maharashtra (ZSI/WGRS; shell H = 4.9 mm). E, F, C. canaliculatus, 10 km west of Mahabaleshwar, Raigad Dist., Maharashtra (ZSI/WGRS; shell H = 9.3 mm). G, H, C. hanumani, Greater Kadambi Falls, Chikmagalur Dist., Karnataka (ZSI/WGRS; shell H = 5.0 mm). Scale bars = 50 Mm.

Figure 8. Distribution of Cremnoconchus species (solid circles). Two or more species names (e.g. syhadrensis + canaliculatus) indicate sympatric occurrence. See Supporting Table S1 for locality details. The shaded area is the Western Ghats region as defined by Irfan-Ullah & Davande (2008). Cities indicated by asterisks.

Figure 16. Radula (A, B) and protoconchs (C–F) of Cremnoconchus species. A, B, C. dwarakii (two views of radula, flat and at 45°), Hulikal Ghat, Udupi Dist., Karnataka (shell H = 6.4 mm). C, C. syhadrensis, Matheran, Raigad Dist., Maharashtra. D, C. canaliculatus, 10 km west of Mahabaleshwar, Raigad Dist., Maharashtra. E, C. agumbensis, Agumbe, Udupi Dist., Karnataka. F, C. dwarakii, Hulikal Ghat, Udupi Dist., Karnataka. Scale bars A, B = 50 Mm; C–F = 0.5 mm. White arrowhead marks junction of protoconch and teleoconch.