Metriorrhynchus inaequalis Fabricius, 1801

Bocak, Ladislav, 2007, A Revision Of Metriorrhynchus (Coleoptera: Lycidae) From The Greater Sunda Islands And Continental Asia, Raffles Bulletin of Zoology 55 (2), pp. 253-260 : 254-256

Metriorrhynchus inaequalis Fabricius, 1801

(Figs. 1–2, 9)

Lycus inaequalis Fabricius, 1801: 112 .

Metriorrhynchus inaequalis – Waterhouse, 1879: 51. Metriorrhynchus notaticollis Pic, 1921: 11 ; Kleine, 1933: 81.

Material examined. – Female, holotype of M. inaequalis (ZMUC) , Sumatra, Daldorff; female, holotype of M. notaticollis (MHNP) , Corporaal, Lau Rakit, Feb.1918.

Others: 1 male ( LMBC), Thailand, Chumphon Prov., Pha To env., 9°48'N 98°47'E, P. Prudek coll., 14–21 Mar.1999 ; 2 males ( LMBC), S. Thailand, Prachvap khirikan, native coll., Feb.1989 ; 2 males ( LMBC), S. Thailand, Ranong, native coll., Feb.1989 ; 1 male, 5 females ( LMBC), Malaysia, Pahang distr., 30 km NE Raub, Lata Lembik , 3°56'N 101°38'E, 200–400 m, coll. E. Jendek and O. Sausa, 22 Apr.–15 May.2002 ; 2 males ( LMBC), Sumatra, SW coast of Ranau lake , 1,200 m, coll. Bolm, 1–4 Jun.2001 ; 1 female ( LMBC), Sumatra, Liwa , coll. L. Dembicky, 2003 ; 5 males, 1 female ( LMBC), S. Kalimantan Prov. , 10 km E of Loksado, 600–1,100 m, 2°43'57"S 115°32'50"E, coll. Bolm, 18–23 Jun.2001 ; 2 males ( LMBC), C Kalimantan Prov. , 60 km SE Muara Teweh, 150 m, 1°20'25"S 115°20'16"E, coll. Bolm, 24–28 Jun.2001 ; 1 male ( BMNH), Quop , W. Sarawak, G. E. Bryant, Mar.–Apr.1914 .

Figs. 1–8. Male genitalia: 1, 2: M. inaequalis ; 3, 4: M. sericeus ; 5, 6: M. laosensis ; 7, 8: M. sericans . Scale bars = 0.5 mm.

Differential diagnosis. – Metriorrhynchus inaequalis is very similar to M. lineatus and these species cannot be identified by colouration or external morphological characters. They differ substantially in the shape of male genitalia (Figs. 1–2, 10) and shape of ovipositor (Figs. 9, 11).

Redescription. – Male: Body medium- to large-sized, parallelsided. Body black, ventral part of thorax and abdomen with light metallic-blue shine. Pronotum black, orange-red or black with lighter pronotal costae. Elytra bright orange to red at least in humeral parts of elytral costae or in opposite extreme elytra brightly coloured except apical tenth of their length. Head small with short rostrum, frontal distance between eyes 1.3 times maximum eye diameter. Antennae acutely serrate, reaching slightly behind middle of elytra. Pronotum at base 1.1 times length at midline. Elytra flat, parallel-sided. Primary costae considerably stronger than secondary ones. Transverse costae dense, regular, cells tiny, transverse. Male genitalia as in Figs. 1–2.

Female: Body usually larger, without any apparent sexual polymorphism. Frontal distance between eyes 1.65 times their maximum diameter. Female genitalia as in Fig. 9.

Measurements. – Body length 7.6–17.0 mm, width at humeri 2.1–4.0 mm.

Distribution. – Peninsular Malaysia, Thailand south of the Isthmus of Kra, Sumatra and Borneo.

Variability. – Metriorrhynchus inaequalis and M. lineatus form mimicry rings with several species from the genera Bulenides , Xylobanus and Cautires (Metriorrhynchinae) . Therefore different colour forms occur in various localities. The pronotum is black in Borneo, but red in Sumatra and Malaysia. The extension of the bright humeral part of the elytra varies between having only red basal quarters of the longitudinal elytral costae to having about 90 percent of the elytra bright orange-red. The body sizes reflect the size of mimics and fluctuate between 7.6 and 17.0 mm.

Remarks. – Only M. notaticollis remains from the extensive list of synonyms given by Kleine (1933). The remaining synonyms are transferred to the synonymy of M. lineatus , which was removed from synonymy and is considered to be a valid species.