Quantula weinkauffiana ( Crosse & Fischer, 1863 )

Deeprom, Kanchanog, Tumpeesuwan, Chanidaporn & Tumpeesuwan, Sakboworn, 2022, A new species of the genus Quantula Baker, 1941 (Eupulmonata: Dyakiidae) from the southern part of north-eastern Thailand, Raffles Bulletin of Zoology 70, pp. 519-533 : 523-527

Quantula weinkauffiana ( Crosse & Fischer, 1863)

( Figs. 3A , 4A , 5A–G ; Tables 1 –3)

Helix weinkauffiana Crosse & Fischer, 1863: 350–351 ; Crosse & Fischer, 1864: 326, pl. 12, fig. 7.

Hemiplecta weinkauffiana – Morlet, 1889: 124; Dautzenberg & Fischer, 1905: 349; Fischer, 1973: 92; Panha, 1996: 34; Panha & Thanamitramanee, 1997: 2.

Ariophanta (Hemiplecta) weinkauffiana – Fischer, 1891: 21.

Ariophanta weinkauffiana inflata Möllendorf, 1894: 149 .

Nanina (Xestina) weinkauffiana – Kobelt, 1900: 984–985, pl. 255, figs. 6–8.

Nanina (Hemiplecta) weinkauffiana var. minor Fischer & Dautzenberg, 1904: 394 .

Dyakia weinkauffiana – Maneevong, 2000: 46–47, figs. 4–11 (A–B).

Ariophanta (Cryptozona) weinkauffiana – Schileyko, 2011: 29–30.

Quantula weinkauffiana – Hemmen & Hemmen, 2001: 45; Nabhitabhata, 2009: 249; Jumlong, 2012: 51,72, figs. 4.10, 5.1; Jumlong et al., 2013: 67–68, 71–76, 79, fig. 2D; Worachak, 2014: 40–43, figs. 4.1–4.3; Worachak et al., 2014: 524–529, fig. 2A; Inkhavilay et al., 2019: 71 , 119 figs. 32B–D, 55H; Sutcharit et al., 2020b: 21 , 23, figs. 9E–F; Jirapatrasilp et al., 2021: 256–257, 261–263, 268–269.

Quantula sp. 2 – Jumlong, 2012: 53, 72, figs. 4.12, 5.1; Worachak, 2014: 45–48, figs. 4.7, 4.8A–E, 4.9A–B

Quantula sp. 5 – Hoompuay, 2016: 40–42, figs. 4.18–4.20

Quantula weinkauffiana inflata – BEDO, 2017: 221.

Quantula weinkauffiana weinkauffiana – BEDO, 2017: 221.

Type locality. Cochinchina (Southern Vietnam) .

Material examined. 37 shells and seven living specimens NHMSU-00035; Khao Panom Sawai , Surin Province; 14°46′05.3″N 103°22′17.0″E; 14 October 2017; ( Figs. 3A , 4A , 5A–E ) .

Diagnosis. Shell depressed-conic. Last whorl angular with sharp peripheral keel and descending in front, lip is rather thick and slightly descending (see Inkhavilay et al., 2019: syntype fig. 32B–D; Jirapatrasilp et al., 2021: Fig. 3 ). Amatorial organ duct shorter than amatorial organ. Gametolytic duct connected to middle part of amatorial organ.

Description. Shell (n= 37) ( Fig. 4A ): dextral, very depressed conic, brown colour with 5–5¼ whorls, suture shallow, growth line fine. Last whorl angular with strong peripheral keel descending in front. Shell height 10.7–15.6 mm, shell width 20.6–28.1 mm. Apex blunt, peripheral keel very sharp, colour of ventral side of shell is paler than that of dorsal side. Apertural lip simple in light brown, with margin slightly thickened in adult specimens. Umbilicus narrow and deep. Body (n=5) ( Fig. 3A ): Living snail light orange, with two lateral dark brown stripes running from each of upper tentacle backward to pneumostome.

Genitalia (n=5) ( Fig. 5A–E ): Penis short, cylindrical. Epiphallus shorter and slender than penis. Inner wall of penis with three very short and thin longitudinal pilasters near atrium, with other regions smooth ( Fig. 5D ). Vas deferens short. Penial retractor muscle absent. Gametolytic sac short with gametolytic duct connecting to middle part of amatorial organ. Amatorial organ cylindrical, gradually larger at distal portion. Inner part of this portion, without longitudinal pilaster, but, with short amatorial organ papilla, which is robust, cylindrical and not exceeding half of distance between distal end of amatorial organ and junction of gametolytic duct. Orange papilla spike present ( Fig. 5B, C ). Inner wall of distal part with transverse lamella or nearly smooth surface, whereas, in proximal part before junction of gametolytic duct with two longitudinal pilasters ( Fig. 5C ). Amatorial organ duct shorter than amatorial organ. Vagina longer than penis. Surface of inner wall of vagina undulated, proximally with thin transverse lamellae ( Fig. 5E ).

Radula (n=5) ( Fig. 5F–G ): There are approximately 78 rows of teeth, each of which comprises 73–173 teeth, formula (19–62) + (17–24) + 1 + (17–24) + (19–62). Central tooth tricuspid, lanceolate, smaller than lateral teeth. Lateral teeth tricuspid, oblique lanceolate. Marginal teeth unicuspid, sword shaped.

Remarks. Images published in Inkhavilay et al. (2019) included the syntype, MNHN-IM-2000-27780 (Fig. 32B), specimens from Savannakhet (Figs. 32C, 55H), and specimens from Champasak (Fig. 32D). The type specimen possesses a sharp peripheral keel and thickened peristome. These characters resemble specimens from Phanom Sawai and in Schileyko (2003: Fig. 1776A), which illustrated the drawing of a shell identified as “ Quantula striata ”. According to the shell morphology and distribution, the shell from Southern Vietnam illustrated in Schileyko (2003) should be identified as Quantula weinkauffiana . However, “ Ariophanta weinkauffiana inflata ” and “ Nanina (Hemiplecta) weinkauffiana minor ”, which were described from localities outside north-eastern Thailand, need clarification of their taxonomic status via further study. From the result of molecular phylogeny of Dyakiidae by Jirapatrasilp et al. (2021), Quantula weinkauffiana individuals from Khao Panom Sawai, Surin ( Thailand), Champasak ( Laos), and Kampot ( Cambodia) were in the same clade with high support (BI= 100%). Considering the result from this study, the intraspecific genetic distances among the Quantula weinkauffiana populations of Laos, Cambodia, and Phanom Sawai were low, as they ranged from 0.2–1.1%, while within the Panom Sawai population, it was 0.2% ( Table 2 ), and the Quantula weinkauffiana clade obtained strong support ( Fig. 2 ) (BI posterior probability of 1.00 and 86% for ML, and 89% for NJ bootstrap replicate).

Distribution. Southern Vietnam, Cambodia, Southern Laos, and North-eastern Thailand ( Crosse & Fischer, 1863; Schileyko, 2011; Inkhavilay et al., 2019; Sutcharit et al., 2020b). In Thailand, this species is currently recorded from Khao Panom Sawai, Surin Province ( Jirapatrasilp et al., 2021 and this study).

Figures

Fig. 3. Living snails of Quantula spp. in the southern part of north-eastern Thailand. A, Q. weinkauffiana (NHMSU-00035) from Phanom Sawai, Surin; B–C, Q. doma, new species: B, NHMSU-00049 from Khao Sala, Surin; C, NHMSU-00051 from Phu Jor Kor, Mukdahan.

Fig. 4. Shell morphology of Quantula spp. in the southern part of north-eastern Thailand. A, Q. weinkauffiana, specimen NHMSU-00035 from Phanom Sawai, Surin; B–C, Q. doma, new species: B, holotype NHMSU-00048 from Khao Sala, Surin; C, NHMSU-00050 from Phu Jor Kor, Mukdahan.

Fig. 5. Quantula weinkauffiana genital system and radula morphology, specimen NHMSU-00035. A, genital system (adapted after Hoompuay, 2016); B–E, inner structure of genital system; B and C, amatorial organ (am); D, penis (p); E, vagina (v); F, right side of central teeth (C) and lateral teeth (L); G, right side of marginal teeth (F & G, adapted from Hoompuay, 2016).

Fig. 2. Bayesian inference (BI) tree of Quantula in this study (Blue colour) determined from 28s and COI genes. Numbers at nodes indicate branch support based on posterior probability (BI)/bootstrapping (ML)/bootstrapping (NJ). # Indicates branches that received <0.50 of posterior probability and received <50% of bootstrap support. - indicates non-supported branches by bootstrap. Scale bar = 0.1 substitutions/site.