Carinartemis sankeyi (Benson, 1859)

Sian Man, Nem, Siriboon, Thanit, Lin, Aung, Sutcharit, Chirasak & Panha, Somsak, 2022, Revision of the carnivorous land snail family Streptaxidae (Stylommatophora, Achatinina) in Myanmar, with description of four new species, ZooKeys 1110, pp. 39-102 : 39

Carinartemis sankeyi (Benson, 1859)

Figs 1 , 2E, F , 19 , 20 , 21C, D , 23 , 24E, F

Streptaxis sankeyi Benson, 1859a: 472. Type locality: Moulmein [Mawlamyine Township, Mon State, Myanmar]. Pfeiffer 1868: 442. Hanley and Theobald 1870: 4, pl. 8, fig. 7. Tryon 1885: 72, pl. 14, figs 2, 3. Blanford and Godwin-Austen 1908: 8, fig. 7.

Streptaxis sankeyanus Stoliczka, 1871: 167, 168, pl. 7, fig. 14 (unjustified emendation). Hanley and Theobald 1870: 4, pl. 8, fig. 7. Nevill 1878: 3. Tryon 1885: 72, pl. 14, figs 9, 10.

Streptaxis hanleyanus Stoliczka, 1871: 168, 169, pl. 7, fig. 15. Type locality: Prope Moulmein, ad flumen Attaran [Attaran River, Mawlamyine, Mon State, Myanmar]. Blanford and Godwin-Austen 1908: 8, 9.

Haploptychius sankeyi - Kobelt 1906: 147, pl. 57, figs 11, 12, pl. 62, figs 6, 7. Richardson 1988: 220. Siriboon et al. 2014b: 169.

Oophana hanleyana - Richardson 1988: 235.

Material examined.

Syntype UMZC I.102740 (6 shells; Fig. 19A ) from Moulmein. Moulmein: NHMUK 1954.6.3.556 (1 shell) ex. Hawkins collection. NHMUK 1906.2.2.341 (4 shells; Fig. 19C ) ex. Blanford collection. NHMUK 1872.9.3.15 (5 shells) ex. Godwin-Austen collection. NHMUK 1903.7.1.4001 (1 shell; Fig. 20A ) ex. Godwin-Austen collection. NHMUK Acc. No. 1733 ex. Oldham collection (2 shells). NHMUK 1888.12.4.792-794 (3 shells; Fig. 19B ). NHMUK 1871.9.23.61 (1 shell; Fig. 19D ). Paboung Toung, Burma: NHMUK 1891.3.17.577-578 (2 shells) ex. Hungerford collection. Mergui: NHMUK 20210051 (1 shell; Fig. 19E ) ex. Cuming collection. Kwengan Hill: NHMUK 1888.12.4.781-783 (3 shells; Fig. 20B ) ex. Blanford collection. Saddan Cave situated on same karsts ~ 600 m south of Kayon Cave , Mawlamyine Township , Mawlamyine District , Mon State, Myanmar (16°31'42.8"N, 97°43'2.1"E): CUMZ 13028 (7 shells). Kayon Cave [previously known as Farm Caves] ~ 10 km from Mawlamyine Township , Mawlamyine District , Mon State, Myanmar (16°32'0.5"N, 97°42'53.5"E: CUMZ 13029 (13 shells; Fig. 20D ), CUMZ 13030 (5 specimens in ethanol). Dhammatat Cave, Mawlamyine Township, Mon State, Myanmar (16°30'23.0"N, 97°48'36.3"E): CUMZ 13031 (12 shells; Fig. 20C ) .

Diagnosis.

Carinartemis sankeyi is superficially similar to C. vesperus and C. striatus in having a subquadrangular aperture, and less expanded and continuous peristome, slender atrium, vas deferens does not pass through a penial sheath, proximal penial hooks located on laterally flattened penial papillae, and distal penial hooks located on laterally compressed penial papillae separated by reticulated folds. In contrast, the shell of C. vesperus has fine transverse ridges (nearly smooth) with few transverse ridges near peristome, varices absent, periphery more extended beyond the diameter of last whorl, lacking parietal lamella, and penial papillae absent. Meanwhile, C. striatus has vas deferens attached to the distal end of penial sheath with very thin connective tissue, and hooks located on papillae without connected longitudinal folds.

Description.

Shell oblique-heliciform, white, translucent; whorls 6-7; spire conical with distinct suture. Shell surface glossy with fine transverse ridge across the entire shell; varices present. Embryonic shell ~ 2½ whorls with smooth surface; following whorls regularly coiled. Shell periphery wide and sharply keeled around nearly the entire penultimate whorl; last whorl axially deflected. Aperture subquadrangular; peristome continuous, thickened, expanded, and reflected. Apertural dentition with one strong parietal lamella. Umbilicus open and deep (Figs 19 , 20 ).

Genital organs. Atrium (at) short, thin and slender. Penis (p) very thin and long. Penial sheath (ps) thin and extending nearly entire length of penis; penial sheath retractor muscle (psr) thin, originating near genital orifice and attached to atrium with short and thin connective tissue, and inserting distally on penial sheath (Fig. 21C ). Vas deferens (vd) runs downwards to curved portion, ~ 1/3 of the penial sheath length, without insertion before entering penis distally (Fig. 21D ). Penial retractor muscle (pr) thin, very long, inserting at penis and vas deferens junction.

Internal wall of atrium generally smooth with sparse atrial pores (Fig. 23A ). Proximal penial wall covered with scattered and pale brownish penial hooks, ~ 12 hooks/200 μm 2. Proximal penial hooks located on laterally flattened penial papillae; hooks small and short (<0.03 mm in length), slightly expanded at base, tips obtuse and curved towards genital orifice (Fig. 23B, C ). Middle and distal penial walls densely covered with pale brownish hooks, ~ 20 hooks/200 μm 2. Middle and distal hooks located on laterally compressed penial papillae separated by reticulated folds; hooks small, short (<0.01 mm in length), slightly expanded at base, and tips pointed (Fig. 23D-G ).

Vagina (v) short, stout and ~ 1/5 of penis length. Gametolytic duct (gd) a long tube extending as far as albumin gland; gametolytic sac (gs) ovate. Proximal free oviduct (fo) enlarged then tapering to smaller diameter in middle section, and slightly enlarged distally. Oviduct (ov) enlarged and folded; prostate gland inconspicuous and bound to oviduct. Talon (ta) small, short and club shaped. Hermaphroditic duct (hd) bearing long seminal vesicle (sv) ca. the same length as from talon to branching point of seminal vesicle (Fig. 21C ).

Vaginal wall generally smooth with vaginal pores, and vaginal hook absent (Fig. 23H ).

Distribution.

This species occurs from three localities in Mon State, southern Myanmar and is likely to be endemic to this area.

Radula .

Each row consists of 43-49 teeth with formula (21-24)-1-(21-24). Central tooth small with pointed cusp. Lateral and marginal teeth undifferentiated, unicuspid and lanceolate. Latero-marginal teeth gradually reduced in size, with outermost teeth much smaller and shorter than inner teeth (Fig. 24D ).

Remarks.

Benson (1859a) introduced C. sankeyi based on a single specimen from ‘Moulmein’. Later, Stoliczka (1871) provided some diagnostic characters with a description of the soft body color and suggested that the Farm-Cave is possibly the correct type locality. This historical locality name refers to a group of caves located on a karst ridge, namely Kayon Hill, situated on the west bank of the Attaran River. At the same time, Stoliczka (1871) proposed Streptaxis hanleyanus based on a single specimen with a small and depressed shell, wide umbilicus, and almost rectangular aperture. However, this holotype specimen was collected from the same geographical area as C. sankeyi . Therefore, we consider this nominal species as a smaller shell form and so treat it as a junior synonym with C. sankeyi .

The original spelling of this nominal species was Carinartemis sankeyi , which was intentionally modified to Streptaxis sankeyanus by Stoliczka (1871) without a clear reason. Therefore, this unjustified emendation name was made available with its authorship and date and became a junior objective synonym (ICZN 1999: Arts 32.3, 33.2.3, 50.5).

Recently, the population collected from Dhammatat Cave showed a more rectangular aperture, slightly compact penultimate whorl, and larger parietal lamella (Fig. 20C ), but this species could only be examined from the empty shells. Therefore, we have to conclude that these differences are an intraspecific variation until more specimens are available, or at least the genitalia.

Figures

Figure 1. Approximate sampling locations used in this study. The location name and coordinates are listed in Table 1. Historical type localities of a broad scale, such as Tavoy, Burma, Moulmein, Mergui, and Tenasserim, are not indicated on this map.

Figure 2. Living snails A Discartemon tonywhitteni from near Phra (Buddha) Cave, Tanintharyi Region (shell width ~ 10 mm) B Discartemon paurodeviatus sp. nov. from the type locality (shell width ~ 11 mm) C Haploptychius heliakosus sp. nov. from the type locality (shell height ~ 9 mm) D Carinartemis exacutus from Lun Nga Mountain, Kayin State (shell height ~ 14 mm) E, F Carinartemis sankeyi (E) from Kayon Cave, Mon State (shell height ~ 10 mm) and (F) from Saddan Cave, Mawlamyine, Mon State (shell height ~ 10 mm).

Figure 19. Carinartemis sankeyi A syntype UMZC I. 102740 from Moulmein B specimen NHMUK 1888.12.4.792 - 794 from Moulmein C specimen NHMUK 1906.2.2.341 from Moulmein with apertural dentition D specimen NHMUK 1871.9.23.61 from Moulmein E specimen NHMUK ex. Cuming collection from Mergui.

Figure 20. Carinartemis sankeyi A specimen NHMUK 1903.7.1.4001 from Moulmein B specimen NHMUK 1888.12.4.781 - 783 from Kwengan Hill C specimen CUMZ 13031 from Dhammatat Cave, Mawlamyine, Mon State with apertural dentition D specimen CUMZ 13029 from Kayon Cave, Mawlamyine, Mon State with apertural dentition.

Figure 21. Genital anatomy of A, B Carinartemis exacutus, specimen CUMZ 13021 A reproductive system and B insertion of vas deferens into penial sheath C, D Carinartemis sankeyi, specimen CUMZ 13029 C reproductive system and D insertion of vas deferens into penial sheath.

Figure 23. Internal sculpture of genitalia of Carinartemis sankeyi, specimen CUMZ 13029 A atrium surface B arrangement of penial hooks on proximal part of penis C lateral view of exposed proximal penial hooks D penial hooks on middle part of penis E arrangement of penial hooks on distal part of penis F uncovered distal penial hooks with pointed tip G distal penial hooks embedded in penial papillae H vaginal surface with vaginal pores.

Figure 24. Radula of specimens A Discartemon tonywhitteni, paratype CUMZ 13001 B Discartemon paurodeviatus sp. nov., paratype CUMZ 13003 C Haploptychius heliakosus sp. nov., paratype CUMZ 13014 D Carinartemis exacutus, specimen CUMZ 13021 E, F Carinartemis sankeyi, specimen CUMZ 13029 E overview of radula and F high magnification of central teeth.