Dicharax ovatus Páll-Gergely & Auffenberg, 2021

Páll-Gergely, Barna, Hunyadi, András, Grego, Jozef, Reischütz, Alexander & Auffenberg, Kurt, 2021, Nineteen new species of Alycaeidae from Myanmar and Thailand (Gastropoda: Caenogastropoda: Cyclophoroidea), Zootaxa 4973 (1), pp. 1-61 : 41

publication ID

https://doi.org/ 10.11646/zootaxa.4973.1.1

publication LSID

lsid:zoobank.org:pub:42EB4BF2-A571-4894-9EEF-783649A27E4F

DOI

https://doi.org/10.5281/zenodo.4771789

persistent identifier

https://treatment.plazi.org/id/038487E6-2F08-2412-FF12-B589FBBDFB1D

treatment provided by

Plazi

scientific name

Dicharax ovatus Páll-Gergely & Auffenberg
status

sp. nov.

Dicharax ovatus Páll-Gergely & Auffenberg n. sp.

Fig. 31A View FIGURE 31

Material examined. Holotype: Thailand, Surat Thani Province, Highway 401, 2.7 km W junction Highway 4142 and 401, evergreen forest on rocky hillside, 9°10’N, 99°40’E, 90 m a.s.l., 19 April 1988, K. Auffenberg leg., below cliff, base of cliff, UF 345330 (D: 1.86 mm, H: 0.99 mm) GoogleMaps . Paratypes: 5 shells, same data as holotype, UF 551223 GoogleMaps . Other Material: 3 broken shells, same data as holotype, UF 551224 GoogleMaps .

Etymology. Named for the ovate (Latin derivation: ovatus ) shell shape (in dorsal view).

Diagnosis. A tiny Dicharax species with depressed shell, finely ribbed R1, R2+R3 less than a quarter whorl, R2 with slightly curved ribs shorter than R2.

Description. Shell off-white, light yellowish; shell outline oval in dorsal view, spire depressed, nearly flat; body whorl rounded; protoconch low, rather glossy, 1.25–1.5 whorls; R1 of 1.25 whorls; R1 with fine, regular, dense ribs, gradually become more widely-spaced and elevated toward R1 termination; boundary between R1 and R2 not conspicuous but discernible due to denser R2 ribs than those of R1; R2 with low ribs that slightly curve toward aperture, ca. 24–26 R2 ribs present; R2+R3 less than quarter whorl (ca. 80˚); R2 slightly shorter than R3; R3 with low ribs of similar density to those on R1; boundary between R2 and R3 clear due to change in rib density and shallow constriction; very low swelling on R3 only indicated; aperture slightly oblique to shell axis, rounded; boundary between inner and outer peristomes distinct; inner peristome thin, slightly protruding and expanded, rather narrow, outer peristome thicker than inner peristome, strongly expanded but not reflected; umbilicus wide, sigmoid, more than a third of shell width.

Measurements. D: 1.81–1.95 mm, H: 0.93–1.1 mm.

Operculum. unknown.

Differential diagnosis. The most similar species regarding size and the dense, fine ribbing is the nearby occurring Chamalycaeus canaliculatus (examined material: Golf von Siam: Koh-Samui, coll. Möllendorff, SMF 109468 About SMF , lectotype), which has a more pronounced constriction at border of R2 and R3, and a narrower swelling on R3 .

Chamalycaeus armillatus ( Benson, 1856) has a more elevated spire, the first 1–1.5 whorls of the teleoconch are smooth and glossy, and the last whorl of R1 has spiral striation. Dicharax parvulus ( Möllendorff, 1887) (examined material: Malakka: Bukit Pondong (Perak), coll. Möllendorff, SMF 109507 About SMF , lectotype, Fig. 31B View FIGURE 31 ) is smaller, has a comparatively larger aperture, a more thickened peristome, and a shorter R2 .

Distribution. This new species is known only from the type locality ( Fig. 3 View FIGURE 3 ).

UF

Florida Museum of Natural History- Zoology, Paleontology and Paleobotany

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