Atmetochilus Simon, 1887

Kunsete, Chawakorn, Sivayyapram, Varat, Traiyasut, Prapun, Thanoosing, Chawatat, Khamwan, Kitiwat & Warrit, Natapot, 2020, Records and redescription of a mygalomorph spider genus ignored for over 100 years with a new species: the genus Atmetochilus Simon, 1887 (Araneae Nemesiidae) in Thailand, Zootaxa 4819 (3), pp. 521-543 : 523-524

Atmetochilus Simon, 1887

Atmetochilus Simon, 1887: 109 ; 1892: 109; 65, fig. 73.

Type species. Atmetochilus fossor Simon, 1887 , by monotypy.

Diagnosis. Differs from other genera in the subfamily Bemmerinae Simon, 1903 by having very large irregular posterior sternal sigilla centrally confluent. It is most closely related to Damarchus Thorell, 1891 and Darmarchilus Siliwal, Molur & Raven, 2015 from which it differs by the large sternal sigilla.

Description. Fovea short, U-shaped. Eyes on tubercle. ALE are largest eyes. No cuspules on labium. Maxilla: serrula absent; ca. 30 cuspules on proximal anterior margin of maxillae in both sexes; in male, maxillary cuspules normally smaller than in female, incipient. Posterior sternal sigilla large and medially confluent with middle pair; anterior sigilla small, indistinct. Palpal tarsus of females with one or two spines; no spines on any leg tarsi of males or females. Males with one sigmoidal (S-shaped) row of teeth on all paired claws; females with 2 rows of teeth on all paired claws; female palp claw with one row of teeth on inner surface of claw. Preening combs normally present on metatarsi III and IV. Cymbium without spines. 4 spinnerets, PMS broad, short and straight, dense small spigots on apical surface and separated by the same distance as their basal diameter. PLS long, triangular, digitiform and length of apical segment as long as median segment, basal segment longest, dense small spigots on ventral surface of all segments. Palpal bulb simple and pyriform; embolus elongate but short in A. koponeni , A. lehtineni and A. sumatranus . Distal tibia I of males with ventral spur and megaspines. Spermathecae divided into two lobes. Head of spermathecae semicircular in A. songsangchotei sp. nov., A. fossor and A. atriceps , curve in A. koponeni , A. lehtineni and A. sumatranus .

Remarks. Atmetochilus was first placed in the family Ctenizidae Thorell, 1887 and only transferred to the family Nemesiidae much later ( Raven 1985).

1) The type of A. fossor in ZSI, Indian Museum is unavailable; not in the Muséum National d’Histoire Naturelle, Paris ( Raven 1985).

2) This genus description was adapted from Raven (1985), Zonstein and Marusik (2016) and also our observations.

Distribution. Myanmar, India, Indonesia (Sumatra) and Thailand.

Species included. A. fossor Simon, 1887 , A. atriceps Pocock, 1900 , A. koponeni Zonstein and Marusik, 2016 , A. lehtineni Zonstein and Marusik, 2016 and A. sumatranus Zonstein and Marusik, 2016 , Atmetochilus songsangchotei Kunsete and Warrit , sp. nov.