Pterocyclos Benson, 1832

Sutcharit, Chirasak, Tongkerd, Piyoros & Panha, Somsak, 2014, The land snail genus Pterocyclos Benson, 1832 (Caenogastropoda: Cyclophoridae) from Thailand and Peninsular Malaysia, with descriptions of two new species, Raffles Bulletin of Zoology 62, pp. 330-338 : 331-333

Genus Pterocyclos Benson, 1832

Pterocyclos Benson, 1832: 11 . Benson, 1836: 356. Troschel, 1848: 44. Benson, 1848: 345. Pfeiffer, 1849: 193. Adams & Adams, 1855: 277. Pfeiffer, 1858: 28. Pfeiffer, 1865: 41. Martens, 1867: 114. Wenz, 1938: 461. Bouchet & Rocroi, 2005: 146.

Steganostoma Troschel, 1837: 163 . Adams & Adams, 1855: 277. Wenz, 1938: 461.

Pterocyclus Agassiz, 1848: 908 [unjustified emendation; ICZN, 1999: Art. 19.1 and 33.2.3]. Nevill, 1878: 260. Fischer, 1885: 745. Kobelt & Möllendorff, 1897: 113. Kobelt, 1902: 160, 161. Kobelt, 1911: 719. Gude, 1921: 97. Vaught, 1989: 15.

Type species. Pterocyclos rupestris Benson, 1832 by monotypy. The specimen that matches best with the original description and figures ( Benson, 1832: 13, pl. 2, fig. 1A – C) is here designated as the lectotype UMZC 2359.1 ( Fig. 3A , no operculum) to stabilise the name. The other specimens become the paralectotypes UMZC 2359.2 (4 shells, Fig. 3B ). The type locality is from “outlying rocks of the Rajmahal range of Hill, India ”. Subsequently, based on differences in the shell colour, Benson (1832: 13) also recognised three varieties (var. 1 – 3) in the same lot of specimens. However, only the syntype UMZC 2359.3 of “var. 3” (1 shell, Fig. 3C ) could be distinguished from the others.

Diagnosis. Apertural lip narrow to wide, wing-shaped and overhanging the accessory respiratory structure. This last structure varies from notch-like to completely tubular in shape. The last whorl is usually completely attached to the penultimate whorl (only in a few species is the last whorl partly separated from the penultimate whorl). Operculum calcareous with a shallow to deep concave profile, inside covered with a corneous layer, and outside with many calcareous counterclockwise multilamellae. These characters made Pterocyclos s.s. different from the other known pterocyclini genera.

External features. Animal shows blackish patches and/ or mottles scattered on a whitish body, faded near mantle cavity ( Fig. 2A – C ). Head with pair of long cephalic tentacles (ct), each containing dark eyespot at outer base ( Fig. 2A ). Anterior body short with genital groove on right side running downwards from anterior end of pallial cavity. Posterior body long, foot broad, with operculum attached dorsally of posterior body. Animal dioecious, male has both long conical external penis (p) on right side below tentacles, and sperm groove (sg) passed along to tip of external penis ( Fig. 2A ); female shows only vaginal groove (vg) on right side ( Fig. 2B ). Lung cavity (lc) has large vein (v) and reticulated vessels. Ctenidium and osphradium absent. Mantle collar (mc) smooth and slightly thickened. Columellar muscle (cm) broad and thickened ( Fig. 2B ).

Genitalia. Testis (te) with branched tubules, bright orange, located around 2 – 3 whorls from apex. Vas deferens (vd) thin, straight tube, connected between testis and prostate gland (pg). Narrow sperm groove connected from genital opening on the right side of snail to tip of external penis. Long cylindrical shaped external penis situated posteriorly below tentacles ( Fig. 2A ).

Female: Ovary (ov) bright orange colour and multi-lobulate glands embedded with brownish digestive glands. Oviduct (od) with thin tube, connected between ovary and uterus (ut) ( Fig. 2B ).

Radula morphology. Typical taenioglossate radula were observed ( Fig. 2D, E ), teeth arranged in v-shaped row, each transverse row contained 7 teeth (2-1-1-1-2). Central tooth large, symmetrical triangular shape, with 2 – 4 well developed cusps on each side. Lateral and marginal teeth slightly slender, inclining to central tooth, with 3 – 4 cusps. Shape of teeth and number of cusps vary among species.

Remarks. Two different spellings, viz. Pterocyclos and Pterocyclus , are widely used in the literature and both attributed to Benson (1832). However, the name Pterocyclus is an unjustified emendation that has been erroneously used as a valid name (e.g., Nevill, 1878; Fischer, 1885; Kobelt & Möllendorff, 1897; Kobelt, 1902, 1911). Wenz (1938) was the first to place Pterocyclus in the synonymy of Pterocyclos . In addition, he attributed the authorship of Pterocyclus to Crosse (1868). However, it now seems that Agassiz (1848: 908) was responsible for this unjustified emendation. Hence, the proper authorship and date of the name Pterocyclus is “ Agassiz, 1848 ” (ICZN, 1999: Art. 50.5).

Nomenclaturally, Pterocyclus Agassiz, 1848 [Mollusca, Gastropoda] is a junior homonym of Pterocyclus Gray, 1846 [ Aves, Passeriformes , Tomaliidae]. Thus, it should not be used as valid generic name (ICZN, 1999, Arts. 23, 52), even if Pterocyclus Gray, 1846 is itself a junior subjective synonym of Garrulax Lesson, 1831 ( Deignan et al., 1964; Sibley & Monroe, 1999).

Figures

Fig. 3. A–D, Shell and operculum of Pterocyclos rupestris: A, lectotype UMZC 2359.1; B, paralectotype UMZC 2359.2; C, syntype of var. 3 UMZC 2359.3; D, operculum from same lot of the paralectotype (showing top, side and bottom views). E, F, Specimens of P. blandi from Langkawi Island, Perlis, Malaysia CUMZ 4582. G, Holotype UMZC 1032 of P. subalatus. H–J, Pterocyclos spaleotes: H, lectotype NMW 1955.158.01107, I, paralectotype NMW 1981.118.02705; J, topotype specimen CUMZ 4585. K, Holotype ZMA Moll. 135622 of P. umbraticus. L–P, Pterocyclos diluvium Sutcharit & Panha, new species: L, holotype CUMZ 4595, M, paratype CUMZ 4588, N, specimen from Gua Cenderawasih, Perlis, Malaysia CUMZ 4592; and O, P, specimens from Tam Tone-din, Kuan-Don, Satun, Thailand CUMZ 4590 showing a: O, uniform whitish shell; and P, dark brown colour patterns. Q–S, Pterocyclos frednaggsi Sutcharit & Panha, new species: Q, holotype CUMZ 4594; R, paratype CUMZ 4581; S, specimen from Gua Pulai, Gua Musang, Kelantan, Malaysia CUMZ 4597.

Fig. 2. A–C, General anatomy of Pterocyclos frednaggsi Sutcharit & Panha, new species, from Gua Musang, Kelantan, Malaysia CUMZ 4944, showing: A, right side of male with testis and external penis; B, right side of female with ovary and vaginal groove; C, left side of female with lung cavity and heart. D, E, Radula morphology of: D, Pterocyclos spaleotes, topotype specimen CUMZ 4585; E, Pterocyclos frednaggsi Sutcharit & Panha, new species, paratype CUMZ 4581.