Helix peroteti Petit, 1841 by subsequent designation of Forcart (1946: 215).

Theshell is oblique-heliciform, usually thin and opaque. Its surface is smooth and glossy but fine transverse ridges may be present. The embryonic shell is smooth. The 5–7 whorls increase regularly. The shell periphery is usually rounded and the last whorl does not descend below the preceding whorl but is parallel to the preceding suture. The outer wall of the last whorl generally possesses two short longitudinal furrows that correspond with internal apertural lamellae. The umbilicus is narrow and deep. The semi-ovate aperture has an expanded peristome with a reflexed lip. The apertural dentition consists of two parietal lamellae; palatal, basal and columellar lamellae are usually present; upper palatal and supracolumellar lamellae may also be present.

Living animals possess a yellowish to reddish reticulated skin. The brown digestive gland and the black kidney are visible through the transparent shell. The upper tentacles are longer than the lower pair with a black eye-spot on the tip of the fully extended tentacle; bright red or yellow retractor muscles show though the transparent skin. The foot is narrow, undivided, the tail short.

Genitalia with a long, slender penis; penial sheath short, about half of penis length; internal wall of introverted penis with black to brown penial hooks; vas deferens passes through a short section of penial sheath before connecting distally to penis; vagina and free oviduct short to long, vaginal hooks may be present; gametolytic duct and sac may not extend as far as albumin gland; seminal vesicle present with about the same length from vesicle to talon.

Perrottetia consists of 27 nominal species distributed across Southern Asia, southern China to northern Vietnam. So far, it was not recorded from Thailand (Kobelt 1906, Yen 1939, Richardson 1988, Panha 1996, Schileyko 2000, Hemmen and Hemmen 2001). “Streptaxis siamensis Pfeiffer, 1862” was provisionally placed in Perrottetia by Kobelt (1906), but the presence of a single large parietal lamella, and the absence of short longitudinal furrows on the outer wall of the last whorl clearly differentiate this species from Perrottetia. Examination of the genitalia of topotype specimens show that this species has a very long penis, with a large proximal gametolytic duct, and short penial hooks that are located on an undulated penial papillae. This indicates that “Streptaxis siamensis Pfeiffer, 1862” should be placed in Oophana Ancey, 1884 (further details of this will be published elsewhere).

The first description of the genital system of a member of the subfamily Streptaxinae Gray, 1860 was published by Gerlach and van Bruggen (1999). Schileyko (2000) included 21 genera within the Streptaxinae. Two of them, Streptartemon Kobelt, 1905, from South America and Seychellaxis Schileyko, 2000, from the Seychelles, share the oblique-heliciform shell, and their penis sheath closely resembles that of Perrottetia. However, these may be plesiomorphic character states, and no phylogenetic affinity can be inferred.

Holotype CUMZ 5001 (Fig. 3A). Measurement: shell height 6.1 mm, shell width 7.7 mm, and with 6 whorls. Paratypes NHMUK 20130062 (2 shells), SMF 341486 (1 shell), CUMZ 5002 (2 shells).

Wat Tam Namsrithong, Nong Kungsi, Kalasin, Thailand, 16°48'18.0"N, 103°16'42.5"E.

Perrottetia mabillei (Bavay and Dautzenberg, 1903) can be distinguished from Perrottetia dermapyrrhosa sp. n. by its lower spire with a distinct suture. The left periphery of the penultimate whorl is shouldered and does not extend beyond the diameter of the last whorl. The aperture is triangular and a supracolumellar lamella is absent. In comparison, Perrottetia peroteti (Petit, 1841) possesses a lower spire with a distinct suture, fine transverse ridges are present and a smaller basal lamella, while upper palatal and supracolumellar lamellae are absent. Perrottetia gudei (Fulton, 1915) (syntype Fig. 3L) differs from Perrottetia dermapyrrhosa sp. n. in its lower spire, the second parietal lamella being smaller and shorter than the first lamella and an upper palatal lamella that is usually present (Petit 1841, Bavay and Dautzenberg 1903, Kobelt 1906, Fulton 1915). In Perrottetia dermapyrrhosa sp. n. the genital atrium is long, the penial sheath reaches about two-thirds of the penial length and the gametolytic duct and sac do not extend as far as the albumin gland. The penial hooks are more scattered and, in the introverted penis, are housed in deep ovate depressions; vaginal hooks are present. In comparison, Perrottetia gudei possesses a short genital atrium and penial sheath, and the gametolytic duct and sac extend as far as the albumin gland; the penial hooks are denser than in Perrottetia dermapyrrhosa sp. n., and each hook is situated on a small papilla (Schileyko 2000, fig. 1015D).

Perrottetia dermapyrrhosa sp. n. differs from Perrottetia aquilonaria sp. n. in its larger shell, which is less deviated from the vertical axis. A sinulus sensu Schileyko (2000) is absent; the first and second parietal lamellae are connected, and a bifid columellar and supracolumellar lamellae are absent. In comparison, Perrottetia dermaphyrrhosa sp. n. possesses a long atrium and vagina, and a penial sheath with a club shaped distal penis. The length of vas deferens that enters the penis distally is longer. The penial papillae are located in hollows, the penial hooks are much more scattered, and vaginal hooks are present.

Shell oblique-heliciform, white and translucent; whorls 6, spire conical, suture distinct; shell surface glossy, with transverse ridges that diminish below the periphery; embryonic shell large, consisting of about 2 whorls with smooth surface, following whorls regularly expanding; shell periphery rounded, last whorl axially deflected; two deep and short longitudinal furrows present; umbilicus narrow (Fig. 3A); aperture subcircular, peristome discontinuous, thickened and expanded; apertural dentition with a large transverse first parietal lamella, with second parietal lamella adjoined at right angles; one upper palatal lamella, one small palatal lamella, one large basal lamella, one long subcolumellar lamella, one large strong columellar lamella and one small supracolumellar lamella (Fig. 3B).

Radula: Teeth arranged in anteriorly V-shaped rows, each row contains 29–31 teeth with formula (14-15)-1-(14-15); central tooth very small and triangular with a pointed cusp; lateral and marginal teeth undifferentiated, unicuspid and lanceolate; lateral teeth gradually reducing in length and size; outer teeth much smaller and shorter than inner teeth (Fig. 6A).

Genital organs: Atrium (at) long and slender; proximal penis (p) long, slender and with solid muscular penis sheath extending distally beyond penis sheath as a narrow tube; penial sheath (ps) reaching about two-thirds of total penis length, penial sheath retractor muscle very thin (psr), originating at atrium and inserting distally on penial sheath (Fig. 4A); vas deferens (vd) passes through about one-sixth of penial sheath length before entering into penis distally (Fig. 4B); penial retractor muscle (pr) thin and very long, inserting at penis and vas deferens junction; internal wall of atrium generally smooth with numerous pores (Fig. 5A); penial wall with scattered and pale brown penial hooks, about 3 hooks/200 µm² (Fig. 5C), and hooks located on conical papillae surrounded by deep ovate hollows; penial hooks of small size (<0.04 mm in length), expanding at base, tip sharp and curved towards genital orifice (Fig. 5E); vagina (v) short, stout, about one third of total penis length; gametolytic duct (gd) a long tube not extending as far as albumin gland, gametolytic sac ovate (gs); free oviduct (fo) very short, oviduct (ov) enlarged and folded; prostate gland inconspicuous and bound to oviduct (Fig. 4A); talon (ta) small, very short and club shaped; hermaphroditic duct (hd) bearing long seminal vesicle (sv) about one and half times longer than the length from talon to branching point of seminal vesicle (Fig. 4C); vagina wall with a corrugated fold and pale brown vaginal hooks, about 8 hooks/200 µm², hooks small (<0.03 mm in length) with pointed tip slightly curving away from genital orifice (Figs 5F, G).

Animal: Live specimens exhibit yellowish-red reticulated skin, and reddish tentacular retractor muscles are visible through the semi-transparent body (Fig. 2A).

The specific epithet “dermapyrrhosa” is derived from the Greek “derma” meaning “skin” and “pyrrhos” meaning “red or yellowish-red”.

This species is known only from the type locality, which is an isolated limestone hill reaching about 300 meters above mean sea level, and which is surrounded by the Korat Plateau.

Up to now, the only description of the reproductive system of a Perrottetia species was that of Perrottetia gudei from Vietnam in which the presence of streptaxid vaginal hooks were recorded for the first time, but without being figured (Schileyko 2000).

Holotype CUMZ 5003 (Fig. 3D). Measurement: height 3.9 mm, shell width 6.6 mm, and with 6 whorls. Paratypes NHMUK 20130064 (2 shells), SMF 341487 (1 shell), CUMZ 5004 (1 shell).

Tam Phra Bumpenboon, Phan, Chiangrai: CUMZ 5005. Wat Tam Pha Jaruey, Pa-daet, Chiangrai: CUMZ 5006. Tam Maesuai, Maesuai, Chiangrai: CUMZ 5007. Tam Chiangdao, Chiangmai: CUMZ 5008. Pha Chu, Nanoi, Nan: CUMZ 5009. Tam Pha Nangkoi, Rongkwang, Phrae: CUMZ 5010.

Wat Tam Pha Plong, Chiangdao, Chiangmai, Thailand, 19°24'7.3"N, 98°55'5.6"E.

Perrottetia aquilonaris sp. n. can be distinguished from the similar south Indian species Perrottetia watsoni (Blanford, 1860) and Perrottetia beddomii (Blanford, 1899) by its smooth shell surface and the presence of a sinulus and a bifid columellar lamella. In comparison, Perrottetia beddomii possesses a supracolumellar lamella, while Perrottetia watsoni hasa second parietal lamella adjacent to the first parietal lamella (Blanford 1860, 1899, Kobelt 1906). Perrottetia gudei from North Vietnam differs from the new species in its larger, oblique-heliciform shell, which is less deviated from the vertical axis. A fine transverse ridge is present at the suture. A sinulus is absent, the peristome is much thicker, and bifid columellar lamella is absent (Fulton 1915). The genital system of Perrottetia gudei differs from that of this new species by possession of a long and slender penis, an entirely free long oviduct, a gametolytic duct and sac extending as far as the albumin gland, the absence of seminal vesicles and a more scattered arrangement of penial hooks (Schileyko 2000).

Shell suboblique-heliciform, white and translucent; teleoconch with 6 whorls, spire convex, suture indistinct; shell surface glossy, with transverse ridges diminishing below the periphery; embryonic shell large, about 2½ whorls, with smooth surface; following whorls regularly expanding; shell periphery shouldered, in apertural view left periphery of the penultimate whorl extending beyond the diameter of the last whorl; last whorl axially deflected; two deep and short longitudinal furrows present; umbilicus narrow (Fig. 3D); aperture subcircular, peristome discontinuous, thickened and expanded, short sinulus present, sometimes with a longer and tapering sinulus (Fig. 3H); apertural dentition consisting of one strong first parietal lamella, a small second parietal lamella separated at right angles, one small upper palatal lamella, one large palatal lamella, one basal lamella and a bifid columellar lamella (Fig. 3E).

Radula: Teeth arranged in anteriorly V-shaped rows, each row containing 21–23 teeth with the formula (10-11)-1-(10-11); central tooth small, sharp, triangular with pointed cusp; lateral and marginal teeth undifferentiated, unicuspid and lanceolate; lateral teeth gradually reduced in length and size, outer teeth much smaller and shorter than inner teeth (Fig. 6B).

Genital organs: Atrium (at) short; penis tripartite, proximal part long and narrow, central section globular with a thick muscular wall, distal section again long and narrow; penial sheath (ps) thin, extends about half of total penis length; penial sheath retractor muscle (psr) very thin, originating at the atrium, inserting distally on penial sheath (Fig. 4D); vas deferens (vd) passes through about one-fifth of penial sheath length before entering into penis distally (Fig. 4E); penial retractor muscle (pr) thin and very long, inserting at penis and vas deferens junction; internal wall of atrium generally smooth with numerous pores (Fig. 5H); penial wall with scattered and pale brown penial hooks about 24 hooks/200 µm²; hooks located on papillae (pl), papillae separated by low reticulated folds; penial hooks of small size (< 0.02 mm in length), expanding at base, tip sharp and curved towards genital orifice (Figs 5J–L); vagina (v) short, stout, about a seventh of total penis length; gametolytic duct (gd) long but not extending as far as albumin gland; gametolytic sac ovate (gs); proximal free oviduct (fo) stout and distally enlarged; oviduct (ov) enlarged and folded; prostate gland inconspicuous and bound to oviduct (Fig. 4D); talon (ta) small, very short and club shaped; hermaphroditic duct (hd) bearing long seminal vesicle (sv) about one and half times longer than the length from talon to branching point of seminal vesicle (Fig. 4F); vaginal wall with parallel vaginal folds; vaginal hooks absent (Fig. 5M).

Animal: Live specimens exhibit yellowish reticulated skin, and pale yellowish tentacular retractor muscles are visible through the semi-transparent body (Fig. 2B).

The specific epithet is from the Latin “aquilonaris” meaning “north or northern”. It refers to the distribution range of this new species in northern Thailand.

This species is known from severallimestone areas in northern Thailand. The animals can be found in altitudes up to 200 meters above mean sea level.

Some variation has been observed in the sinulus and the bifid columellar lamella. Populations from Chiangmai and Chiangrai Provinces possess a longer and tapered sinulus (Figs 3G, H). Specimens collected between those two provinces have a shorter sinulus, and specimens from Chiangmai possess a large bifid columellar lamella (Fig. 3H).

Holotype CUMZ 5011 (Fig. 3I). Measurement: shell height 5.0 mm, shell width 6.9 mm, and with 6¼ whorls. Paratypes NHMUK 20130066 (2 shells), SMF 341488 (2 shells), CUMZ 5012 (14 shells).

Tam Kangkao, Phuphaman, Khonkaen: CUMZ 5013.

Phuphaman National Park, Phuphaman, Khonkaen, Thailand, 16°45'34.0"N, 101°57'50.3"E.