Alionchis Goulding & Dayrat, 2018

Goulding, Tricia C., Khalil, Munawar, Tan, Shau Hwai & Dayrat, Benoît, 2018, A new genus and a new species of onchidiid slugs from eastern Indonesia (Gastropoda: Euthyneura: Onchidiidae), Raffles Bulletin of Zoology 66, pp. 337-349 : 341

Alionchis Goulding & Dayrat , new genus

Type species: Alionchis jailoloensis , designated here

Etymology. The genus Alionchis is a combination of Ali, a collector and assistant to Alfred Russel Wallace during his travels across the Malay Archipelago, and Onchis , one of the names used to refer to onchidiid slugs. Ali began working for Wallace in Borneo, first serving as cook, and later collecting and preparing specimens ( Van Wyhe & Drawhorn, 2015). Ali’s collections of birds and natural history observations greatly contributed to Wallace’s knowledge of the fauna in the region. This genus is named to honor Ali’s contribution to studies of biodiversity in the Malay Archipelago. Ali actually got married on the island of Ternate, near Halmahera, and settled there, which, given the geographic distribution of Alionchis , makes the new genus name especially fitting.

Diagnosis. Body slightly flattened. Notum soft (gelatinous). No dorsal gills. Dorsal eyes present on notum. Retractable, central papilla (with four dorsal eyes) present. Foot wide, approximately two thirds of total width. Eye tentacles thick and long. Eyes at tip of ocular tentacles. Pneumostome median, at posterior margin of hyponotum. Female opening adjacent to anus. Male opening below right ocular tentacle. Intestinal loops of type II, type III, and intermediate between types II and III. No rectal gland. No penial hooks. No accessory penial gland.

Diagnostic features. Externally, Alionchis can be reliably distinguished from other onchidiid genera by the unusually thick eye tentacles and the pneumostome at the very posterior end of the hyponotum. The squishy, gelatinous texture of the notum is also distinctive (in live animals).

Remarks. A new generic name is needed for the new species described here because it does not belong to any of the known genera and no existing generic name could apply to it (for a recent review of the application of all onchidiid genus-group names, see Dayrat et al., 2017). The position of the pneumostome in Alionchis is unique. It is at the posterior end of the hyponotum, close to the hyponotum edge (but still on the hyponotum surface), which cannot be confused with any other onchidiid genus. In Peronina Plate, 1893 , the pneumostome also is at the posterior end of the hyponotum, but it is not on the hyponotum surface (Goulding et al., in press-b). Instead, it is right at the margin between the ventral hyponotum and the dorsal notum. In other onchidiids, the pneumostome is on the hyponotum, approximately equally distant between the foot and the hyponotum edge. The eye tentacles of Alionchis are also unique. They are much thicker than in all other onchidiid genera. Only one species of Alionchis is described here, but the position of the pneumostome and the unique eye tentacles will likely be shared by other species in this genus because these traits usually do not vary within a genus. For instance, all three species of Onchidium share long and thin eye tentacles ( Dayrat et al., 2016) and all three species of Peronina (Goulding et al., in press-b) share the same pneumostome position.