Cissidium triangulum, Darby, Michael, 2019

Darby, Michael, 2019, New Ptiliidae (Coleoptera) from Sarawak in the spirit collection of the Natural History Museum, London, European Journal of Taxonomy 512, pp. 1-50 : 19-21

publication ID	https://doi.org/ 10.5852/ejt.2019.512
publication LSID	urn:lsid:zoobank.org:pub:8DF89CFD-A549-4C69-8FBC-90EC8DEA9A66
DOI	https://doi.org/10.5281/zenodo.5941284
persistent identifier	https://treatment.plazi.org/id/A30AC317-C75D-4534-8360-F895711D5285
taxon LSID	lsid:zoobank.org:act:A30AC317-C75D-4534-8360-F895711D5285
treatment provided by	Plazi
scientific name	Cissidium triangulum
status	sp. nov.

Treatment

Cissidium triangulum View in CoL sp. nov.

urn:lsid:zoobank.org:act:A30AC317-C75D-4534-8360-F895711D5285

Figs 6F View Fig , 7F View Fig , 8F View Fig , 9B View Fig

Diagnosis

The triangular shape of the mentum distinguishes this species from all others.

Etymology

Refers to the form of the mentum.

Type material

Holotype MALAYSIA-BORNEO • Sarawak, Mulu ; Mar. 1978; N.M. Collins leg.; pitfalls in alluvial forest; BMNH.

Paratypes

MALAYSIA-BORNEO • 1 spec.; same data as for holotype but 13 Mar. 1978; BMNH • 1 spec.; Sarawak, 4 th division, Gunung Mulu National Park ; May–Aug. 1978; P.M. Hammond and J.E. Marshall leg., BM 1978-49 ; base comp litter around long house; BMNH .

Description

SIZE. Habitus ( Fig. 6F View Fig ), length 0.79 mm.

COLOUR. Elytra dark brown, pronotum and head yellow brown, antennae, legs, dorsal surface covered with long yellow pubescence.

HEAD. Distance across eyes 0.22 mm; antennomeres III–XI, length 0.31 mm; mentum triangular the anterior margin much longer than the basal, stipes also triangular, broadest at base ( Fig. 9B View Fig ).

PRONOTUM. Length 0.19 mm, width 0.28 mm, shallowly foveolate, sides straight before right angled hind angles, disc without pubescence ( Fig. 7F View Fig ).

ELYTRA. Length 0.41 mm, width 0.34 mm, pubescent, shallowly foveolate, sides evenly rounded, broadest before middle.

VENTRUM. Mesoventrum without pubescence, collar extending onto humeri without a terminal tooth, lateral margins almost straight before turning to meet mesocoxae, keel becoming rugose before narrowing to a point between the mesocoxae ( Fig. 8F View Fig ). Metaventrum with scattered pubescence throughout, posterior margin between metacoxae with two sharp points at corners, metacoxae separated by ¼ width of the sclerite.

Remarks

The form of the mentum and the mesoventral characters suggest that this species belongs either to a subgenus of Cissidium or to a separate genus.