Carinartemis vesperus Siriboon & Panha, 2014

Siriboon, Thanit, Sutcharit, Chirasak, Naggs, Fred, Rowson, Ben & Panha, Somsak, 2014, Revision of the carnivorous snail genus Indoartemon Forcart, 1946 and a new genus Carinartemis from Thailand (Pulmonata: Streptaxidae), Raffles Bulletin of Zoology 62, pp. 161-174 : 168-171

Carinartemis vesperus Siriboon & Panha , new species

( Figs 1 , 2B , 6 B–E, 7A, B, 8A–F, Table 1)

Type material. Holotype CUMZ 5019 ( Fig. 6B ). Measurement: shell height 6.9 mm, shell width 9.6 mm, 7 whorls . Paratypes: CUMZ 5020 (3 shells), 6200 (60 shells; Fig. 6C, D ), 6201 (2 specimens in ethanol; Figs 2B , 7A, B , 8 A–F) , NHMUK 20130077 (2 shells) , SMF (2 shells), and ZRC (2 shells).

Type locality. Khao Kling , Khao Yoi District, Phetchaburi, Thailand. Rock crevices on isolated limestone hill reaching about 100 m above mean sea level (13°15'36.5"N, 99°48'14.8"E) .

Other material examined. Khao Yoi, Khao Yoi District, Phetchaburi ( CUMZ 6202). Khao Yoi, Phetchaburi ( NMW.1955.158.25233, Fig. 6E ).

Etymology. The specific epithet “ vesperus ” from a Latin term for “west” refers to the locality of the new species in the west of Thailand.

Diagnosis. Carinartemis vesperus , new species, can be distinguished from H. mirificus ( Möllendorff, 1894) in having a higher spire, peripheral keel around nearly the entire penultimate whorl, a subcircular aperture, and in lacking apertural lamellae. While H. mirificus has a lower spire, a peripheral keel around less than half of the penultimate whorl, a triangular aperture, and a strong and triangular parietal lamella.

Compared with H. exacutus ( Gould, 1856) and H. sankeyi ( Benson, 1859) , this new species differs by having a strong peripheral keel around nearly the entire penultimate whorl, having the last whorl less inflated and much deviated from the vertical axis, and in lacking strong apertural lamellae. Whereas, these two species exhibit a strong peripheral keel over less than half of the penultimate whorl, and have the last whorl inflated and less deviated from the vertical axis. The apertural dentition of H. exacutus has two parietal lamellae and H. sankeyi has a strong parietal lamella.

Carinartemis vesperus , new species, differs from C. striatus , new species, by having a smaller shell with weaker transverse ridges, the area below the periphery of the penultimate whorl smooth, a short longitudinal furrow in the umbilical area, and in lacking apertural lamellae. The genitalia have a short penis and vagina, and a thick penial sheath with the vas deferens passing it. Penial papillae are absent, and vaginal hooks are present. Whereas C. striatus , new species, has a larger shell, strong transverse ridges over the entire shell, no longitudinal furrow in the umbilical area, and has a prominent parietal lamella. The genitalia have a long penis and vagina and a very thin penial sheath with the vas deferens attached to its distal end. Penial papillae are present, and vaginal hooks are absent.

Description. Shell suboblique-heliciform, white and translucent; whorls 7, spire conical with distinct suture. Shell surface glossy, with thin and fine transverse ridges; ridges disappear below periphery of penultimate whorl and around umbilicus. Embryonic shell with about 2½ whorls and smooth surface; following whorls regularly expanding. Shell periphery wide and sharply keeled around nearly entire penultimate whorl; last whorl axially deflected. Umbilicus widely open and deep with short longitudinal furrow. Aperture subcircular, peristome discontinuous, thickened, and expanded. Apertural dentition usually without lamellae, but sometimes with small parietal lamella, and rarely with very small other lamellae ( Fig. 6B ).

Radula. Teeth arranged in anteriorly V-shaped rows, each row containing 47–49 teeth with the formula (23-24)-1-(23- 24); central tooth small, short, triangular with pointed cusp. Lateral and marginal teeth undifferentiated, unicuspid, and lanceolate; lateral teeth gradually reduced in length and size with outer teeth much smaller and shorter than inner teeth ( Fig. 8F ).

Genital organs. Atrium (at) short. Proximal penis (p) long, slender; becoming slightly broader with short pouch before tapering distally. Penial sheath (ps) thick, extending about fourth-fifths of total penis length; penial sheath retractor muscle (psr) very thin, originating at atrium and body wall ( Fig. 7A ). Vas deferens (vd) long, slender; slightly broadened before tapering distally; passes through about one-tenth of penial sheath length before entering into penis distally ( Fig. 7B ). Penial retractor muscle (pr) thin and very long, inserting distally on penis at the penis and vas deferens junction.

Internal wall of atrium smooth with numerous atrial pores ( Fig. 8A ). Penial papillae absent; pale brown penial hooks present, about 40 hooks/200 μm 2. Penial hooks short (<0.03 mm in length), expanding at base, tips obtuse and curved towards genital orifice ( Fig. 8B, C ).

Vagina (v) very short and stout. Gametolytic duct (gd) long, extending as far as albumin gland; gametolytic sac ovate (gs). Free oviduct (fo) long, proximally large with equivalent diameter with vagina, and tapering to smaller tube distally. Oviduct (ov) enlarged and folded; prostate gland inconspicuous and bound to oviduct. Talon (ta) small, short and club shaped. Hermaphroditic duct (hd) bearing seminal vesicle (sv) about as long as the length from talon to branching point of seminal vesicle ( Fig. 7A ).

Vaginal wall with transparent vaginal hooks about 8 hooks/200 μm 2; hooks located on oblique parallel vaginal folds. Vaginal hooks short (<0.04 mm in length), expanding at base, tips obtuse slightly curving away from genital orifice ( Fig. 8D, E ).

Distribution. This new species seems to be the restricted to limestone in western Thailand at the type locality and at Khao Yoi, Phetchaburi, the limestone karst about 10 km east of the type locality.

Remarks. Shell variation can be observed in five paratypes by having very small parietal lamella and the detectable upper palatal, palatal, basal and columellar lamellae ( Fig. 6D ). In addition, a single shell from Khao Yoi, Phetchaburi ( Fig. 6E ; NMW.1955.158.25233) has a strong parietal lamella and four other very small peripheral lamellae. However, we considered this conspecific based on the characters of thin and fine transverse ridges and broadly expanded apertural lip, and because it was collected within the range of this species. However, further anatomical and molecular data of the newly collected specimen with precise locality will elucidate whether this represents intraspecific variation or a separate taxon.

Figures

Fig. 1. Distribution map of Indoartemon spp. and Carinartemis spp. Indoartemon spp (white circle): (1) Indoartemon cingalensis (Benson, 1853); (2) Indoartemon layardianus (Benson, 1853); (3) Indoartemon glacilis (Collett, 1898); (4) Indoartemon eburneus (Pfeiffer, 1861); (5) Indoartemon fuchsianus (Gredler, 1881); (6) Indoartemon bidens (Möllendorff, 1883); (7) Indoartemon tridens (Möllendorff, 1898); (8) Indoartemon laevis (Blanford, 1899); (9) Indoartemon prestoni (Gude, 1903); and (10) Indoartemon medius, new species. Carinartemis spp. (black circle): (1) Carinartemis vesperus, new species; and (2) Carinartemis striatus, new species.

Fig. 2. Living snails of: A, Indoartemon medius, new species, paratype CUMZ 5017 (shell width about 8 mm); B, Carinartemis vesperus, new species, paratype CUMZ 6201 (shell width about 10 mm); C, Carinartemis striatus, new species, paratype CUMZ 6205 (shell width about 12 mm).

Fig. 6. A, Shell of Stemmatopsis poirieri lectotype MNHN 26980; B–E, Shells of Carinartemis vesperus, new species, (B) holotype CUMZ 5019 with apertural dentition, (C, D) paratype CUMZ 6200 from Khao Kling, Khao Yoi District, Phetchaburi, and (E) specimen NMW 1955.158.25233 from Khao Yoi, Petchaburi; F, G, Carinartemis striatus, new species, (F) holotype CUMZ 6203 with apertural dentition, and (G) paratype CUMZ 6117 from Tam Kra Sae, Sai Yok, Kanchanaburi.

Fig. 7. Genitalia of Carinartemis spp: A, B, Carinartemis vesperus, new species, paratype CUMZ 6201, (A) reproductive system, and (B) insertion of vas deferens into penial sheath; C, D, Carinartemis striatus, new species, paratype CUMZ 6205, (C) reproductive system, and (D) attachment of vas deferens into distal end of the penial sheath.

Fig. 8. Internal sculpture of genitalia of Carinartemis spp: A–F, Carinartemis vesperus, new species, paratype CUMZ 6201, (A) details of atrial pore on the atrium surface, (B) high magnification of penial hooks, (C) top view of penial hook, (D) arrangement of vaginal folds with hooks, (E) high magnification of vaginal hook, and (F) radula morphology. G–K, Carinartemis striatus, new species, paratype CUMZ 6205, (G) details of atrium surface, (H) low magnification shows arrangement of penial hooks, (I) low magnification shows arrangement of vaginal folds, (J) high magnification of penial hooks, and (K) radula morphology.