Schistoloma maydelineae Páll-Gergely, P.K. Nguyen & Y. Chennew

Páll-Gergely, Barna, Nguyen, Phi Khanh & Chen, Yansen, 2019, A review of Vietnamese Schistoloma Kobelt, 1902 with a list of all known species of the genus (Caenogastropoda: Cyclophoroidea: Pupinidae), Raffles Bulletin of Zoology 67, pp. 322-327 : 323-325

Schistoloma maydelineae Páll-Gergely, P.K. Nguyen & Y. Chennew species

( Fig. 2 )

Type material. Holotype (H: 21.2 mm, D: 9 mm) ( HNHM 103476 ), Vietnam, Khánh Hoà Province, Khánh sƠn, 11°58.7′N, 109°3.6′E, coll. Phi Khanh Nguyen, 16 April 2018; HA / 1 paratype, YSC / 6 paratypes, MEM / 2 paratypes, SA / 5 paratypes, same data as holotype.

Diagnosis. A middle-sized Schistoloma species with strongly ribbed conical shell, slight indication of a periumbilical keel, and a white, conspicuous suture.

RAFFLES BULLETIN OF ZOOLOGY 2019

Description. Shell shape high conical, widest at its base, yellowish brown; some shells (e.g., holotype) with dark redpurple protoconch and upper whorls, others with brownishyellowish apical whorls; protoconch consists of 3 whorls, opaque, without any notable sculpture; teleoconch with strong but low ribs that are paler than rest of shell; ribbing becoming less regular towards aperture, because ribs have perpendicular projections, which do not extend neighbouring ribs, and some ribs are not complete (they do not reach both sutures); the most irregularly sculptured area is on the body whorl, where the sculpture looks “hammered”; below suture a “pseudosuture” is visible (slight groove just below the suture), which ends in a conspicuous pale coloured sutural area; aperture circular, straight, or slightly reverse oblique to the shell axis (i.e., in lateral view, basal part of the peristome situated more anteriorly than upper part); peristome continuous, expanded and very slightly reversed, especially in basal part; peristome slender, sharp in lateral view, sometimes looks like double (i.e., formed by the inner and outer peristomes); umbilicus open, slit-like, with a very slight indication of a periumbilical keel, which is formed by the angled ribs. Operculum unknown.

Measurements. H: 19.7–21.6 mm, D: 8.4–9.2 mm (n = 6).

Differential diagnosis. This species can be distinguished from any congeners by its ribbed shell and white suture. Furthermore, Schistoloma maydelineae new species differs from S. messageri by the absence of umbilical keel, the more slender, conical shell, and the strongly reticulated sculpture. Schistoloma inermis and Schistoloma croesus also possess a smooth shell that is smaller than S. maydelineae new species.

Type locality. Vietnam, Khánh Hoà Province, Khánh sƠn, 11°58.7′N, 109°3.6′E .

Etymology. This new species is named after the daughter of the last author, Maydeline Faith Chen.

Distribution. This new species is thus far known only from the type locality.

Figures

Fig 2. A, Schistoloma maydelineae new species, holotype HNHM 103476; B, Sculpture and suture of upper whorls; C, Sculpture of the last whorl. Photographs by: B. Páll-Gergely. Scale “a” = 10 mm and refers to fig. A, scale “b” = 5 mm and refers to figs. B and C.