Alycaeus rolfbrandti Maassen 2006
Creators: name: Páll-Gergely, Barna
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Animalia
Mollusca
Gastropoda
Architaenioglossa
Alycaeidae
Alycaeus
Alycaeus rolfbrandti

description: Alycaeus rolfbrandti Maassen, 2006
(Figs 1I–S, 2C, F)
Alycaeus rolfbrandti Maassen, 2006: 136–137, figs 6–9.
Alycaeus rolfbrandti — Páll-Gergely et al., 2017: 10, fig. 3B; Páll-Gergely et al., 2020: 23, fig. 2B.
Type material. Type specimens were not examined by us, but other shells from the original series were available (see under additional material).
Additional material examined. LAOS: South-Central Laos, Khammouan Province, ca. 13.5 km N of Thakhek (Muang Khammouan), ca. 5 km SE of Ban Nakok, under limestone rocks in dry secondary forest under W facing cliff, limestone, clay, alt. 138 m, 17°30.984′N, 104°47.682′E (locality code: 9L07), leg.Abdou,A. & Muratov, I. V., 30 November 2007, MNHN-IM- 2012-27322/3 complete + 1 broken shell (Fig. 1Q); South-Central Laos, Khammouan Province, ca. 15 km NE of Thakhek (Muang Khammouan), ca. 1.25 km SE of Ban Nase, near large flooded cave under W facing cliff, limestone, clay, black soil on limestone, on and under rocks in dry secondary forest, alt. 127 m, 17°30.547′N, 104°53.444′E (locality code: 7L07), leg. Abdou, A. & Muratov, I. V., 28 November 2007, MNHN-IM-2012 -27325/8 shells + some shell fragments (Fig. 1O); South-Central Laos, Khammouan Province, ca. 9 km NE of Thakhek (Muang Khammouan), NW facing cliff, limestone, clay, black soil in limestone pockets, on and under rocks in dry secondary forest on and under, alt. 190 m, 17°26.757′N, 104°52.937′E (locality code: 6L07), leg. Abdou, A. & Muratov, I. V., 27 November 2007, MNHN-IM- 2012-27321/19 complete shells + some shell fragments (Figs 1P, 2C, F); South-Central Laos, Khammouan Province, ca. 15.5 km ENE of Thakhek (Muang Khammouan), on and under limestone rocks in dry secondary forest under NW facing cliff, limestone, clay, black soil in limestone pockets, alt. 155 m, 17°26.817′N, 104°57.200′E (locality code: 12L07), leg. Abdou, A. & Muratov, I. V., 01 December 2007, MNHN-IM- 2012-27320/1 shell (Fig. 1S); South-Central Laos, Khammouan Province, ca. 15 km ENE of Thakhek (Muang Khammouan), in the upper entrance of the large cave on NW facing steep slope, limestone, clay, black soil on limestone, on and under limestone rocks in dry secondary forest, alt. 157 m, 17°26.650′N, 104°56.944′E (locality code: 11L07), leg. Abdou, A. & Muratov, I. V., 01 December 2007, MNHN-IM- 2012-27324/5 damaged shells (Fig. 1R); Kalkberge ca. 20 km östl. Takek, leg. Brandt, 08 September 1963, SMF 262540 (1 shell; labelled the holotype of “ Alycaeus carinatus Brandt ”, but not mentioned by Maassen 2006, Fig. 1I–L); Same data, SMF 262541 (5 shells, labelled as paratypes of “ Alycaeus carinatus Brandt ”, but not mentioned in Maassen 2006; consequently, these shells are part of the original series of A. rolfbrandti, but they are not paratypes since Maassen clearly had not examined them); South-Central Laos, Khammouan Province, ca. 10.5 km E of Thakhek (Muang Khammouan), on and under rocks, cave deposits, in secondary forest under entrance and in large cave on NE facing steep slope, limestone, clay, black soil on limestone, alt. 160 m, 17°24.340′N, 104°54.894′E (locality code: 25L07), leg. Abdou, A. & Muratov, I. V., 09 December 2007, MNHN-IM- 2012-27323/2 complete + 2 broken shells (Fig. 1M); South-Central Laos, Khammouan Province, 2 km NWW of Ban Na village, Pha Suang Cave – S entrance, 17°33.054′N, 104°52.414′E (locality code: JG 3), leg. Grego, J., 09 February 2017, JG/9, PGB /2; South-Central Laos, Khammouan Province, NE foot of Pha Soung Mountain, caverns among slope boulders, 17°33.108′N, 104°52.301′E (locality code: JG 4), leg. Grego, J., 08 February 2017, JG/4; South-Central Laos, Khammouan Province, 6 km SSE of Ban Na, Tham Dan Makhia, lake cave entrance, 17°30.616′N, 104°53.475′E (locality code: JG 7), leg. Grego, J., 13 February 2017, JG/4; Khammouane Province, Nhommalath, bridge on road no. 12, 43.4 km towards Nongchan, southern edge of Ban Khamhé, right side of the road, 210 m a.s.l., 17°34.743′N, 105°27.515′E (locality code: 2019/108), leg. A. Hunyadi, 30 September 2019, HA/10; Khammouane Province, 40 km from the centre of Thakhek, Mahaxay, 2.3 km southeast from Ban Na Coc, limestone wall, 155 m a.s.l., 17°25.957′N, 105°09.669′E (locality code: 2019/95), leg. A. Hunyadi, 27 September 2019, HA/4 (Fig. 1N); Bam Na Ka Yak (Nhoum) (exact locality unknown), leg. Saurin between 1950 and 1970, MNHN-IM- 2012-27296/1 shell; Nhommanth (exact locality unknown), leg. Saurin, MNHN-IM- 2012-27295/31 shells (shells not keeled, identical to MNHN-IM- 2012-27325).
Diagnosis. A very large alycaeid species with dominant, usually keeled last whorl (shell wider than high), finely reticulate protoconch, finely wrinkled/scaly R1, a very long R2 having ribs forming many connections with each other by calcareous projections, and a long R3 with low swelling.
Operculum: Unknown.
Measurements (in mm). D = 8.9–11.3, H = 6.4–8.9 (multiple populations, n = 27).
Variation in specimens. The examined shells show variability in terms of shell size and the sharpness of the keel.
Differential diagnosis. Differs from A. eydouxi by the web-like structure of the R2 ribs, and the roughly sculptured protoconch. Moreover, most populations of A. rolfbrandti have strongly keeled body whorl. See also under A. goliath n. sp.
Distribution. This species is known form the limestone region on the left bank of the Mekong River, east of Nakhon Phanom (Laos, Khammouan Province). The furthest distance between the known populations is ca. 70 km (Fig. 4).
Remarks. This species does not require redescription due to the accurate original description. Only one addition has to be made: the R2 ribs either form projections to join each other, or they are regularly undulated, which results in a wire fence-like surface.
The majority of the populations examined have typically keeled last whorl, although specimens of some examined populations have a bluntly keel, i.e., the body whorl is almost rounded (JG4, JG7 = 7L07), while it is rounded in one population (2019/95) (see Fig. 1M–S). I found no other differences between these morphotypes, therefore they are not separated at any taxonomic levels.
description: Published as part of Páll-Gergely, Barna, 2023, Revision of the Alycaeidae of China, Laos and Vietnam (Gastropoda: Cyclophoroidea) II: The genera Alycaeus and Pincerna, pp. 253-276 in Zootaxa 5249 (2) on pages 258-259, DOI: 10.11646/zootaxa.5249.2.4, http://zenodo.org/record/7687418