Cissidium triangulum Darby, 2019

Darby, Michael, 2020, A revision of Cissidium Motschulsky (Coleoptera: Ptiliidae) with seventy seven new species, European Journal of Taxonomy 622, pp. 1-188 : 134-135

Cissidium triangulum Darby, 2019

Figs 4E , 85

Material examined

Holotype

MALAYSIA • Sarawak, Mulu ; pitfalls in alluvial forest; Mar. 1978; N.M. Collins leg.; genitalia not dissected; BMNH.

Supplementary description

The following description amplifies the type description of Darby (2019), in particular by adding more details of the meso- and metaventral characters, in order to conform with the entries in the present paper.

SIZE. Habitus ( Fig. 85A ), length 0.79 mm.

COLOUR. Yellow brown, antennae, legs, and pubescence yellow.

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. 4E ).

PRONOTUM. Length 0.19 mm, width 0.28 mm, pubescent, shallowly foveolate; sides rounded then straight before rectangular hind angles, border crenulate, not continuing along posterior margin, median emargination angulate ( Fig. 85B ).

ELYTRA. Length 0.41 mm, width 0.34 mm, pubescent, the pubescence slightly longer than on the pronotum, shallowly foveolate.

MESOVENTRITE. Median extension of collar parallel-sided, short, mid-keel setose and rugose before keel; keel narrow, tapering to a point at the base of the mesocoxae; mesoventral lateral margins almost straight before turning to meet mesocoxae, then obscured; humeri barely toothed ( Fig. 85C ).

METAVENTRITE. With scattered pubescence throughout, disc plain, length 0.14 mm, distance across spines 0.08 mm; mesocoxal posterior margins without serrations.

Remarks

The only species of Cissidium from Sarawak in this group.

Figures

Fig. 4. Menta and submenta. A. Cissidium petri Darby, 2015, × 1380. B. Cissidium tigrum Darby, 2015, × 1220. C. Cissidium amboroense Darby, 2015, × 1260. D. Cissidium losbanos sp. nov., × 1100. E. Cissidium triangulum Darby, 2019, × 650. F. Cissidium pilosellum sp. nov., × 1420.

Fig. 85. Cissidium triangulum Darby, 2019. A. Habitus. B. Pronotum, × 555. C. Mesoventrite showing median process of collar, mid-keel and keel, × 575.