Dicharax rugosus (Godwin-Austen, 1914)

Fig. 33F–N

Alycaeus rugosus Godwin-Austen, 1914: 359, pl. 141 figs 7, 7a.

Dicharax sajodentatus Gittenberger & Choki Gyeltshen in Gittenberger et al., 2024: 200, figs 19, 21. Syn. nov.

Alycaeus (Dicharax) rugosus – Gude 1921: 268–269.

Chamalycaeus (Dicharax) rugosus – Ramakrishna et al. 2010: 66.

Metalycaeus rugosus – Páll-Gergely et al. 2020: 154.

Diagnosis

The combination of the strongly ribbed R1, the rather centrally located R3 swelling, the large distance between the inner and outer peristomes and the fringed aperture distinguishes this species from its congeners.

Type material examined

BHUTAN • holotype of Dicharax sajodentatus (Fig. 33K–N) (photographs examined) .

INDIA • 3 syntypes of D. rugosus (figured specimen indicated by pink wool; Fig. 33F–J); Burroi Gorge, Dafla; NHMUK 1903.7.1.2641 .

Type localities

“Burroi Gorge, Dafla Hills” ( A. rugosus); “ Samdrup Jongkhar Dzongkhag: N of Bangtar, Phuntshothang, 26°53’N 91°42’E, 375 m a.s.l.” ( D. sajodentatus).

Differential diagnosis

For differences with newly described Bhutanese species ( D. zhemdentatus, D. trashidentatus, D. umbiclausus and D. aspidentatus) see Gittenberger et al. (2024) (under the name D. sajodentatus). See also under C. asaluensis, C. crispatus, C. dohertyi and D. muspratti .

Remarks

During the examination of A. rugosus, we found traces of a spiral striation on the teleoconch, based on which we classified that species in the genus Metalycaeus (see Páll-Gergely et al. 2020). However, the re-examination revealed that those spiral lines were probably part of lower shell layers of the corroded syntypes, and moreover, Gittenberger et al. (2024) described several similar species from Bhutan that can undoubtedly be assigned to Dicharax .

The comparison of syntypes of D. rugosus and D. sajodentatus revealed that their shell shape, sculpture and formation of the peristome are identical; therefore, we treat the latter as a synonym of the former.