A new genus of air-breathing marine slugs from South-East Asia (Gastropoda, Pulmonata, Onchidiidae)

Abstract

As part of an ongoing effort to revise the taxonomy of air-breathing, marine, onchidiid slugs, a new genus, Laspionchis Dayrat & Goulding, gen. nov., is described from the mangroves of South-East Asia. It includes two new species, Laspionchis boucheti Dayrat & Goulding, sp. nov., and Laspionchis bourkei Dayrat & Goulding, sp. nov., both distributed from the Malacca Strait to the Philippines and Australia. This study is based on extensive field work in South-East Asia, comparative anatomy, and both mitochondrial (COI and 16S) and nuclear (ITS2 and 28S) DNA sequences. The two new species are found in the same habitat (mud surface in mangrove forests) and are externally cryptic but are distinct anatomically. Both species are also strongly supported by DNA sequences. Three cryptic, least-inclusive, reciprocally-monophyletic units within Laspionchis bourkei are regarded as subspecies: L. bourkei bourkei Dayrat & Goulding, ssp. nov., L. bourkei lateriensis Dayrat & Goulding, ssp. nov., and L. bourkei matangensis Dayrat & Goulding, ssp. nov. The present contribution shows again that species delineation is greatly enhanced by considering comparative anatomy and nuclear DNA sequences in addition to mitochondrial DNA sequences, and that thorough taxonomic revisions are the best and most efficient path to accurate biodiversity knowledge.

Systematic revision of the genus Peronia Fleming, 1822 (Gastropoda, Euthyneura, Pulmonata, Onchidiidae)

“…It is very important to note that this method does not redefine the types of intestinal loops, it merely clarifies them, and the difference between the types I and II originally defined by Plate and Labbé is maintained. According to Plate and Labbé, type I is characterized by a transitional loop oriented to the right in dorsal view, at 3 o'clock (Dayrat et al 2019b: Fig. 1A), and type II is characterized by a transitional loop oriented to the left in dorsal view, at 9 o'clock (Dayrat et al 2019b : fig.…”

“…According to Plate and Labbé, type I is characterized by a transitional loop oriented to the right in dorsal view, at 3 o'clock (Dayrat et al 2019b: Fig. 1A), and type II is characterized by a transitional loop oriented to the left in dorsal view, at 9 o'clock (Dayrat et al 2019b : fig. 1C).…”

Systematic revision of Platevindex Baker, 1938 (Gastropoda: Euthyneura: Onchidiidae)

“…Even though onchidiid slugs are one of the dominant groups of gastropods in the mangrove forests of South-East Asia and Australia, they have often been overlooked in surveys of mangrove invertebrates. This is likely due to their camouflage with mud and tree bark, but also because many species, even from different genera, are extremely difficult to distinguish (e.g., slugs of the genera Paromoionchis Goulding, 2019 andLaspionchis Dayrat &Goulding, 2019;Dayrat et al 2019aDayrat et al , 2019b. Some of the challenges with onchidiid taxonomy are those that taxonomists often face: few specimens from mangroves available in museum collections, type material often destroyed or lost, and difficulty in identifying informative characters (Dayrat 2009).…”

“…Some of the challenges with onchidiid taxonomy are those that taxonomists often face: few specimens from mangroves available in museum collections, type material often destroyed or lost, and difficulty in identifying informative characters (Dayrat 2009). In spite of those difficulties, the taxonomy of the onchidiids is being revised systematically, genus by genus, based on an unprecedented effort in collecting fresh material worldwide (Dayrat et al 2016(Dayrat et al , 2018(Dayrat et al , 2019a(Dayrat et al , 2019b(Dayrat et al , 2019c(Dayrat et al , 2019dGoulding et al 2018aGoulding et al , 2018bGoulding et al , 2018c.…”

“…Three genera have been described over the last few years for species formerly included in the genus Onchidium as well as species newly discovered; these include Wallaconchis Goulding & Dayrat, 2018, found in sandy mangroves and coral rubble (Goulding et al 2018b), Marmaronchis Dayrat & Goulding, 2018, found on rocky shores (Dayrat et al 2018) and Paromoionchis from muddy mangrove forests (Dayrat et al 2019a). Three additional genera of mangrove onchidiids were described based entirely on new species: Melayonchis , 2019c, Laspionchis (Dayrat et al 2019b), and Alionchis Goulding & Dayrat, 2018(Goulding et al 2018. Two other existing genera of onchidiids associated with mangroves have also been revised: Onchidina Semper, 1882 and Peronina Plate, 1893 (Goulding et al 2018c).…”