Revision of the Mecodema curvidens species group (Coleoptera: Carabidae: Broscini) Author Seldon, David S. Author Leschen, Richard A. B. text Zootaxa 2011 2829 1 45 journal article 10.5281/zenodo.202857 b87540e9-6bcc-498c-aa22-1047a893372f 1175-5326 202857 Mecodema atrox Britton, 1949 (redescription) Figure: 5, 25. Mecodema atrox Britton, 1949 : 52 . Diagnosis. Head, body broad and flat. Clypeus with a single setose puncture on each side bearing 2 setae. Prothoracic carina narrow, crenulated and extended to beyond anterior angle. Pronotal fovea shallow and narrow. Elytra striae with regularly distributed, small asetose punctures. Setose punctures of 3rd ventrite absent, may be present on 4th ventrite and present 5th ventrite. Apical portion of aedeagus symmetrically rounded with a strong twist to right of vertical axis. Dorso-apical portion of central spicule, not greatly expanded. Basal lobe of left paramere rectangular, arm relatively large and apical lobe medium, with setation along apical ¾ of ventral edge. Description. Length 17–22 mm . Colour black. Head, body broad and flattened. Microsculpture of frons and vertex absent. Vertexal groove narrow and defined entire length. Form of microsculpture on anterior area of clypeus, sulcate. Clypeus with a single setose puncture on each side, bearing 2 setae. Form of lobes of mentum, square. Submentum constriction narrow with 6 setae. Prothoracic carina narrow, crenulated and extended beyond anterior angle. Pronotum broad and flat, posterior lateral sinuation parallel or slightly angled outward, pronotal fovea shallow and narrow, rugose microsculpture may be present laterally on pronotal disc. Elytra broad and flat, striae with regularly distributed small asetose punctures, intervals slightly convex. Setose punctures of mesocoxae present, absent on metacoxae. Setose punctures of 3rd ventrite, absent, may be present on 4th ventrite and present 5th ventrite. Apical portion of aedeagus symmetrically rounded with a strong twist to right of vertical axis. Dorso-apical portion of central spicule, not greatly expanded. Left paramere basal lobe rectangular, arm relatively large, apical lobe relatively medium, with setation along apical ¾ of ventral edge. Comments. This species was described by Britton (1949) based on a single male specimen. The specimen is in poor condition with antennomeres 6–11 of right antennae missing; last 3 tarsal segments of right mid-leg and left fore-leg missing; all tarsal segments missing from right and left hind-legs; entire left mid-leg missing; genitalia card mounted and pinned with specimen. Mecodema atrox is found on the lower slopes of the Coromandel Ranges, northern Kaimai Ranges, is sister species to M. aoteanoho (Great Barrier Is.) and M. haunoho (Little Barrier Is.) , and along with M. occiputale , is basal to this monophyletic group (fig. 5). The scarcity of specimens may be due to the ruggedness of the region in which this species is found; as a result, the Department of Conservation has listed this species as endangered and declining due to habitat loss ( McGuinness 2002 ). FIGURE 22. Two illustrations of the posterior / lateral area of the protibia that show the differences in form between the genera: (a) Mecodema and (b) Oregus . All species within the genus Mecodema have a concave posterolateral area (pla), an extension of the dorsal apical area forms a pointed process (dap), and the claw inward of the cleaning organ has a flattened extension dorsally that is possibly a protective structure for the fine setae of the cleaning organ. The species of the genus Oregus have a relatively flat posterolateral area, the dorsoapical process is absent, and the cleaning organ claw is without the dorsal flattened extension (scale bars = 1 mm). FIGURE 23. The differences in the shape of the apex of the central (tooth) spicule (dorsal view) between the genera Oregus (a & b) and Mecodema (c–f) can be seen in these pictures. The genus Oregus (outgroup) has two central spicules: (a) the ventral one forms a pointed spike (black arrow) below the anterior part of the rounded dorsal spicule (white arrow). The setose flanges (b) can be seen attached to the base of the spicule and the left flange is larger than the right flange in Oregus . Whereas, in the genus Mecodema (d) there is a single central spicule (black arrow) and the (e) left setose flange is smaller (white arrow) than the right flange (black arrow). The same structures are marked for M. infimate (f), central spicule (black arrow) and left setose flange (white arrow), the right setose flange is absent. FIGURE 24. Three illustrations showing the different states of microsculpture on the vertex and frons: (a) the absence of cuticular microsculpture on the frons and vertex ( curvidens group); (b) the presence of cuticular microsculpture on the frons and vertex ( Mecodema ingroups); (c) represents the outgoup Oregus (scale bar = 3 mm). Distribution. North Island: Bay of Plenty (BP), Coromandel and northern Kaimai Ranges. Type locality: Tauranga. Holotype : Male labelled ( NZAC ) Type [round label with red border] / Tauranga N.Z. 20-26 - 3-31 E.S. Gourlay / HOLOTYPE Mecodema atrox n. sp. [hw] E.B. Britton. det. 1946 [date hw] / E.S. Gourlay Acc. 1970 Ent. Div. / NZ Arthropod Collection NZAC 04011260 . Other material examined: BP: 2, Lower Kaimai Ranges Tauranga 1950 G. Ramsay ( NZAC ); 1, Ruahiki Lower Kaimai 1979 J.C. Watt ( NZAC ); CL: 1, Tairua Coromandel Range 1993 Larivière Larochelle ( NZAC ); 1, card mounted Lower Kaimai, Tauranga, 25.1.50 , G. Ramsey (underside of card) / E.S. Gourlay Acc. 1970 Ent. Div / Mecodema atrox Britton, 1949 det. A. Larochelle ( NZAC ); 1, NEW ZEALAND CL Tairua 13 km N., rte 25 24.1.1990 A Larochelle, M-C Larivière / Kauri for., in big rotten log ( NZAC ).