Friday, June 28, 2024

[Mollusca • 2024] Durgella pentata & D. nulla • Unveiling the Diversity of the Semislug Gnus Durgella Blanford, 1863 (Eupulmonata: Helicarionidae) from Thailand and Myanmar, with Description of Two New Species


Durgella pentata Pholyotha & Panha, sp. nov.
Durgella nulla Pholyotha & Panha, sp. nov.

in Pholyotha, Sutcharit, Lwin et Somsak, 2024.
 
Durgella is a terrestrial semislug genus in the family Helicarionidae and currently comprises nine species recorded from Thailand and Myanmar. Two species, D. concinna and D. rhaphiellus, have been described based only on shell information, while the taxonomy of the remaining seven species is comprehensively treated herein using comparative morphology. Revised species descriptions are given for D. levicula, D. erratica, D. siamensis, and D. libas; D. birmanica (previously placed in the Megaustenia) is moved to this genus; and two speciesD. pentata Pholyotha & Panha, sp. nov. and D. nulla Pholyotha & Panha, sp. nov., are described as new to science. Based on our findings, the combination of shell characters including shape, size, aperture, and umbilicus; the number of mantle extensions; and the genitalia, especially the penis, epiphallus, and dart apparatus, can be used to distinguish these nine species. Among these ninerecognised species, only D. nulla Pholyotha & Panha, sp. nov. has no dart apparatus.

Key words: Comparative morphology, Durgellinae, Indochina, Land snail, Systematics, Taxonomic revision

 
TAXONOMY
Superfamily Helicarionoidea Bourguignat, 1877
Family Helicarionidae Bourguignat, 1877
Subfamily Durgellinae Godwin-Austen, 1888

Genus Durgella Blanford, 1863

Durgella birmanica (Pfeiffer, 1847)
Durgella levicula (Benson, 1859) 
Durgella erratica (Godwin-Austen, 1888) 
Durgella concinna Blanford & Godwin-Austen, 1908

Durgella rhaphiellus (Martens, 1867)
Durgella siamensis Möllendorff, 1902 
Durgella libas Solem, 1966 


Durgella pentata Pholyotha & Panha, sp. nov.

Diagnosis: Shell depressedly subglobose, thin, polished, dark yellow with a creamy tinge, and aperture roundly lunate, broader than high; animal with five mantle extensions; genitalia with very short vagina, small epiphallic caecum, short gametolytic duct, and very large dart apparatus.

Etymology: The specific name “pentata” is from the Greek word meaning five, referring to the presence of five mantle extensions


Durgella nulla Pholyotha & Panha, sp. nov.

Diagnosis: Shell depressedly subglobose, membranous, polished, dark yellowish with olive tinge; animal with two different colours: upper body dark brown or blackish and from lower body to foot margin creamy; four mantle extensions; genitalia with very large penis, short gametolytic duct, and without dart apparatus.

Etymology: The specific name “nulla” is from the Latin adjective meaning not any, none, nobody, or no, and refers to the absence of dart apparatus


Arthit Pholyotha, Chirasak Sutcharit, Ngwe Lwin and Panha Somsak. 2024. Unveiling the Diversity of the Semislug Gnus Durgella Blanford, 1863 (Eupulmonata: Helicarionidae) from Thailand and Myanmar, with Description of Two New Species. Zool Stud. 63:14. DOI: 10.6620/ZS.2024.63-14.

หอยหางดิ้น สกุล 𝐷𝑢𝑟𝑔𝑒𝑙𝑙𝑎 ชนิดใหม่ของโลก 2 ชนิดจากประเทศไทยและเมียนมาร์ คือ
1. 𝐷𝑢𝑟𝑔𝑒𝑙𝑙𝑎 𝑝𝑒𝑛𝑡𝑎𝑡𝑎 Pholyotha & Panha, 2024 
หอยหางดิ้นเชียงดาว ค้นพบที่ อ.เชียงดาว จ.เชียงใหม่
2. 𝐷𝑢𝑟𝑔𝑒𝑙𝑙𝑎 𝑛𝑢𝑙𝑙𝑎 Pholyotha & Panha, 2024 
หอยหางดิ้นอีสาน ค้นพบที่ จ.เลยและหนองบังลำภู