Anceyoconcha sp.1

Nahok, Benchawan, Tumpeesuwan, Chanidaporn & Tumpeesuwan, Sakboworn, 2021, Two new species of genus Anceyoconcha S. Tumpeesuwan & C. Tumpeesuwan, in Nahok et al., 2020 (Gastropoda: Pulmonata: Camaenidae), from northeastern Thailand, Raffles Bulletin of Zoology 69, pp. 555-569 : 565-567

publication ID 10.26107/RBZ-2021-0072

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Anceyoconcha sp.1


Anceyoconcha sp.1

Figs. 3F View Fig , 6 View Fig ; Tables 1–3

Anceyoconcha sp.2 – Nahok, 2020: 74–75, figs. 25E, 40, 46–47, 50, 53, tables 3, 5, 7–10. Pha Nam Yoi, Roi Et.

Material examined. 1 shell (NHMSU-00043) ( Fig. 3F View Fig ), Pha Nam Yoi , Nong Phok District, Roi Et Province, Thailand (16°19′39.38″N, 104°19′1.69″E), alt. 278 m, 3 September 2017, SH = 19.1 mm, SW = 9.2 mm, AH = 5.2 mm, AW = 5.7 mm; 1 living specimen preserved in ethanol (NHMSU-00044), same locality as previous lot GoogleMaps .

Diagnosis. Shell ovate conic and stout. Flagellum shorter than epiphallus. Flagellum ⅓ of penis length.

Description (empty shell = 1, living specimen = 1). Shell ( Fig. 3F View Fig ; Table 3): broadly rounded and stout, whorls 7¾, shell height 19.1 mm, shell width 9.2 mm, aperture height 5.2 mm, and aperture width 5.7 mm. Pale grey to light yellow, transparent, and shining. Apex obtuse. Aperture half-moon-shaped.

Genital system (n = 1) ( Fig. 6A, B View Fig ): atrium short. Penis long cylindrical shape with proximal bend. Penial retractor muscle short. Epiphallus longer than penis. Flagellum length is half of penis length, and hook-shaped at distal end. Vas deferens long. Vagina is longer than penis. Gametolytic duct thickened and swollen at base, and gradually slender to small tube distally. Gametolytic sac is small swollen gland at distal end of gametolytic duct. Free oviduct very short. Uterus and prostate gland long and stout. Inner penial wall with oblique lamellae ( Fig. 6C View Fig ). Proximal part of epiphallus (ep1) inner wall with five corrugated longitudinal pilasters ( Fig. 6C View Fig ). Distal part of epiphallus (ep2) inner wall with rather smooth surface ( Fig. 6D View Fig ). Inner wall of flagellum with smooth and robust longitudinal pilasters ( Fig. 6E View Fig ). Inner vaginal wall with six slightly undulating longitudinal pilasters ( Fig. 6F View Fig ).

Radula (n = 1) ( Fig. 6G–I View Fig ): comprises 100 transverse rows of teeth, each row containing 51–59 teeth, (19–21) + (6–8) + 1 + (6–8) + (19–21). Central teeth symmetric unicuspid, broadly rounded. Lateral teeth similar to central tooth, but are oblique and cusps are wider and longer. Teeth on both sides begin to transform into indistinct bicuspid marginal teeth with tiny ectocone at numbers 7–9. Marginal teeth gradually change to broad tricuspid, starting at numbers 10–18, and begin to transform to tetracuspid with two small cusp ectocones from numbers 19–27 to edge of radula plate.

Remarks. Anceyoconcha sp.1 differs from all Anceyoconcha species by its ovate conic and stout shell. Although the shell of Anceyoconcha sp.1 looks similar to that of “ Pseudobuliminus ” ovoideus Thach & Huber, in Thach, 2018, the former possesses inflated whorls, rather deep suture, a calloused inner lip, and inclined columella side, whereas the latter possesses flat whorls, simple suture, calloused inner lip, and straight columella side. Moreover, “ Pseudobuliminus ” ovoideus was described from the area between Dalat and Phan Rang, Southern Vietnam, approximately 700 km away from the locality of Anceyoconcha sp.1 , which is found in the center of northeastern Thailand. We propose that both taxa are different species. The genitalia of Anceyoconcha sp.1 resemble that of A. elongata , new species from Phu Po, with its long, cylindrical penis with a proximal twist at its base, and a gametolytic duct that is thickened and curved at its base ( Figs. 5 View Fig , 6 View Fig ). According to the Bayesian inference tree based on the concatenated genes of COI, 16S rRNA, and 28S rRNA, Anceyoconcha sp.1 is clearly separated from A. carinata with very strong support (1.00 for BI posterior probability, and 100% and 97% bootstrap support for NJ and ML, respectively), and belongs to a different clade from A. elongata , new species ( Fig. 2 View Fig ). However, the number of examined specimens of this species is only one living snail and one empty, incomplete shell, which is insufficient for an assessment of intraspecific variation or to distinguish different species. Therefore, ‘ Anceyoconcha sp.1 ’ is used for Anceyoconcha from this locality for the time being, until more complete specimens can be found and studied.

Distribution. Anceyoconcha sp.1 is currently known from Pha Nam Yoi, Nong Phok District, Roi Et Province.

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