Clavicornaltica sabahensis Schilthuizen, Seip & Otani

Schilthuizen, Menno, Seip, Lilian A, Otani, Sean, Suhaimi, Jadda & Njunjic, Iva, 2017, Three new minute leaf litter beetles discovered by citizen scientists in Maliau Basin, Malaysian Borneo (Coleoptera: Leiodidae, Chrysomelidae), Biodiversity Data Journal 5, pp. 21947-21947 : 21947

Clavicornaltica sabahensis Schilthuizen, Seip & Otani sp. n.

Materials

Type status: Holotype. Occurrence: catalogNumber: BOR/COL/14089 ; recordedBy: Iva Njunjić; Menno Schilthuizen; Taxon Expeditions; sex: 1 female; lifeStage: adult; preparations: card-mounted; disposition: in collection; Taxon: scientificName: Clavicornalticasabahensis; order: Coleoptera; family: Chrysomelidae; genus: Clavicornaltica; specificEpithet: sabahensis; taxonRank: species; scientificNameAuthorship: Schilthuizen, Seip & Otani; Location: continent: Asia; island: Borneo; country: Malaysia; stateProvince: Sabah; municipality: Tongod; verbatimLocality: Maliau Basin, near Studies Centre, along Seraya Trail, where stream enters the river; verbatimElevation: 260 m; verbatimCoordinateSystem: decimal degrees; decimalLatitude: 4.7389; decimalLongitude: 116.9696; Event: samplingProtocol: Winkler, litter from basis of trees; samplingEffort: 15 l of leaf litter; eventDate: 2017-09-27; habitat: lowland dipterocarp forest; fieldNumber: TxEx-MBSC1wb; Record Level: institutionID: Universiti Malaysia Sabah; collectionID: Institute for Tropical Biology and Conservation, BORNEENSIS; institutionCode: UMS; collectionCode: BORN; basisOfRecord: PreservedSpecimen

Description

Body dark reddish brown, small, oval and convex, ca. 0.75 mm long and ca. 0.58 mm wide (Fig. 10a). Eyes ca. 1/7 the width of the head. Antennae yellowish brown; clava long and moderately robust. Female wingless. Tibia and tarsus yellowish brown, femur dark brown and robust. Male unknown.

Head (Fig. 10b): Rectangular, shallowly and sparsely punctate; vertex smooth; frontal tubercles present, frontal carina absent. Eyes ca. 1/7 the width of the head in dorsal view. Antennae: clava long and moderately robust (Fig. 11).

Pronotum: Lenticular in dorsal view, convex, four angles angular with a deep furrow along the length of the edge, which itself is somewhat angular in the middle with two deep seta-bearing pores: one at ¼ of the margin’s length, the other in the posterior angle. Punctuation covers the entire surface in an irregular pattern and is the same strength as the dorsal surface of the elytra.

Hind wings: Absent.

Elytra: Striae punctiform, punctures shallower dorsally, more deeply impressed laterally and becoming less visible towards the very apex. A deep but narrow punctuated groove runs along the entire margin continuing to the apex; apex itself slightly drawn out.

Legs: Metafemur robust, oval, covered in fine white setae. Metatibia bearing eight minute setae which cover the terminal one-quarter along the external edge and one long spine, slightly shorter than the first tarsomere, provided with three minute teeth (Fig. 12).

Abdomen: Carina on the first abdominal sternite sharp and narrow.

Diagnosis

Differential comparisons were made with all known species of the genus. Clavicornaltica sabahensis sp. n. differs from these in the following respects. Clavicornaltica buechei Medvedev, 2008 (Sulawesi): is larger (1.4 mm) and the ridge on the first abdominal segment is widened posteriorly ( Medvedev 2008). Clavicornaltica mizusawai Suenaga & Yoshida, 2016 (Taiwan) has impunctate elytra and larger eyes ( Suenaga and Yoshida 2016). Clavicornaltica sakishimana Suenaga & Yoshida, 2016 (Japan) has the carina on the first abdominal sternite widened caudally ( Suenaga and Yoshida 2016). Clavicornaltica pusilla Scherer, 1974 and C. loebli Scherer, 1974 (Sri Lanka) have impunctate elytra ( Scherer 1974). C. besucheti Scherer, 1974 (Sri Lanka) is larger, 1.5-2.2 mm ( Scherer 1974). Clavicornaltica malayana Medvedev, 1996 (Malaysia) has the pronotum impunctate ( Medvedev 1996). Clavicornaltica iriana iriana Medvedev, 1996 (New Guinea) is larger (1.2-1.4 mm), has larger eyes, only 4-5 rows of punctures on the elytra and these do not continue to the apex ( Medvedev 1996). Clavicornaltica iriana sarawacensis Medvedev, 1996 (Borneo) is larger (1.2-1.4 mm) and the elytral punctures are only visible laterally ( Medvedev 1996). Clavicornaltica takizawai Doeberl, 2009 (Nepal) is larger (1.45 mm) and its frons and vertex are densely punctuated ( Döberl 2009). Clavicornaltica mussardi Scherer 1974 (Sri Lanka) is larger (1.3-1.5 mm) ( Scherer 1974). Clavicornaltica rileyi Döberl, 2002 (India) is larger (1.5 mm) and its eyes are larger ( Döberl 2002). Clavicornaltica dali Konstantinov & Duckett, 2005 (Yunnan): punctures on the head are stronger and those on the pronotum weaker than in C. sabahensis sp. n. ( Konstantinov and Duckett 2005). Clavicornaltica tarsalis Medvedev, 1996 (Irian Jaya) is larger, 1.6 mm and the ridge on the first abdominal sternite is anteriorly broadly widened ( Medvedev 1996). Clavicornaltica australis Konstantinov, 1996 (Queensland) lacks the long seta in the middle of the pronotal edge ( Konstantinov and Duckett 2005). Clavicornaltica fortepunctata Scherer, 1974 (Sri Lanka): elytral punctuation fades abruptly before the apex ( Scherer 1974). Clavicornaltica trautneri Medvedev, 1993 (Philippines) is much larger (2.1 mm) ( Medvedev 1996). Clavicornaltica takimotoi Lesage, 1997 (Taiwan) is more globular and the punctures on the dorsum of the elytra are nearly invisible ( Suenaga and Yoshida 2016). Clavicornaltica philippinensis Scherer, 1979 (Philippines) is larger (1.3 mm) ( Medvedev 1996). Clavicornaltica tamdao Konstantinov & Duckett, 2005 (Vietnam): terminal setae on the metatibia are more numerous (12 in C. tamdao versus 8 in C. sabahensis sp. n.) and cover a larger section of the tibia (the terminal one third) ( Konstantinov and Duckett 2005). Clavicornaltica vietnamensis Konstantinov & Duckett, 2005 (Vietnam): apex of the elytra is less extended ( Konstantinov and Duckett 2005).

Etymology

Since this is the first species of Clavicornaltica found in Sabah, the specific epithet sabahensis ("inhabitant of Sabah") was chosen. This was one of several names suggested during a naming ceremony in Maliau Basin Studies Centre on 6 October 2017, in which expedition participants as well as a large number of field centre staff and porters took part.

Distribution

Known only from one location in the valley where the Maliau river flows out of Maliau Basin, at 260 m elevation (Maliau Basin Studies Centre).

Taxon discussion

Only a single female was at the authors' disposal. Nonetheless, the authors felt confident that this specimen represents an undescribed species. First of all, given their small size, apterism/brachypterism, and habitat (leaf litter in forests), it is unlikely that Clavicornaltica species have wide ranges ( Konstantinov and Duckett 2005) and the only species known from Borneo and its immediate vicinity have external characters that do not match C. sabahensis sp. n. (see under Diagnosis). Moreover, C. sabahensis sp. n. carries a combination of traits that make it easily recognisable. Specifically, these are its extremely small size, highly vaulted shape, dark colouration, narrow ridge on the first abdominal sternite, angular, thick pronotal margin, and strong punctuation on the entire elytra.