Mecodema pluto Britton 1949
Creators: name: Seldon, David S.
name: Buckley, Thomas R.
Publisher: name: Zenodo
Year: 2019
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Carabidae
Mecodema
Mecodema pluto

description: Mecodema pluto Britton, 1949.
Figures 12B and 47.
Diagnosis: Distinguished from other Mecodema species by: 1, pronotum with 4–6 setae along pronotal carina (curvidens species group). Differing from other curvidens group species by: 2, the presence of a distinctive raised ridge anterad vertexal groove; 3, the overall pronotal shape is ovate; 4, elytral interval 9 broad and shortened, i.e. not extended to humeral angle.
Description: Length 15.8–23 mm, pronotal width 4.5–5.6 mm, elytral width 5.1–6.9 mm. Colour of entire body matte to glossy black, coxae and legs may be dark red.
Head: Narrow and convex (Fig. 14D). Vertex smooth (Fig. 47); vertexal groove shallow and narrow, defined entirely and very distinctive by raised posterior edge of frons; large supraorbital puncture bearing 3 setae; 2 welldefined supraorbital grooves; frons medially convex with a small and shallow depression each side of midline; frontoclypeal suture indistinct, tentorial pits (Fig. 9) small; anterior area of clypeus with narrow grooves, 1 setose puncture each side bearing 2 setae (Fig. 47). Labrum rounded, anterior edge outwardly curved with 2 proximate central setae, 2 setae each side evenly spaced. Mentum lobes squared (Fig. 12G), median process broad and short, sligthly angled upward (15°), moderately indentate (Fig. 12B); mentum setae present. Submentum sclerite constriction broad with 6–8 setae (2 setae spaced distantly laterally). Stipes with 2 basal setae. Gula pits small, suture defined, gula (Fig. 8) flat with transverse lines. Gena with very fine lines forming an isodiametric pattern across entire area.
Prothorax: Prothoracic carina narrow the entire length, slightly crenulated with 4–6 setae each side (Fig. 47), extended to anterior angle; posterior lateral sinuation (Fig. 11) evidently carinate, parallel, indistinctly crenulated; prontum narrow and moderately deflected, overall shape ovate (Fig. 47); midline impressed, anterior medial and posterior medial diamond-shaped impressions present; disc may have very fine, transverse wrinkles laterally; pronotal foveae deep and narrow; anterior edge distinctly inwardly curved, posterior edge inwardly curved medially. Prosternum concave without microsculpture; proepisternum without microsculpture. Procoxal setae absent; protibia distally expanded and shovel-like (Fig. 10B).
Elytra: Narrow and moderately deflected; humeral angle anteriorly convergent (Fig. 6A); basal margin moderately curved and steeply bevelled (almost vertical) to base, intervals 6–8 truncated by raised carina laterally proximate to humerus, interval 1 extended to margin; lateral carina (Fig. 1) narrow the entire length, extended to humeral angle; humerus with 2 setose punctures proximate to angle; suture impressed, but no more so than striae; all striae with small, regularly distributed, asetose punctures (in some specimens striae 1–4 punctures may be obsolescent); intervals 1–4 weakly convex, intervals 5–9 moderately convex with interval 9 broadened and shortened, not extended to humeral angle; interval microsculpture present as transverse lines; 7 th strial setal pattern with 1–2 setose punctures in anterior ½, 3–5 setose punctures in posterior ½ (Fig. 47), setose punctures large.
Ventral surface: Mesepisternum and metepisternum with rugose wrinkles present; setose punctures present on mesocoxa (2) and metacoxa absent. All abdominal ventrites (Fig. 2) finely lineate laterally; ventrites 3–5 without setose punctures; ventrite 6 setae present: ♂ with 2–3 setose punctures each side, proximate junction of straight apical edge and curve anterad, ♀ with 2 broad setose punctures relatively proximate bluntly rounded apex; ventrites without foveae. Anterior metaventrite process a bluntly rounded triangle with a well-defined, apically broadened to laterally narrowed carina.
Male genitalia: Apical portion of penis lobe asymmetrically rounded with a moderate deflection to right of vertical axis (VV) (Fig. 15B); apex of penis lobe symmetrically curved upward, dorsal curve flattened (Fig. 47 PL); shaft of penis lobe narrowed apically but gradually broadened basally, curve to right absent (VV); overall length of penis lobe slightly curved ventrally (LV) (Fig. 16A). Structures of the endophallus (Fig. 4): lateral form of the apex of the central spicule rounded; dorsal form of the apex of the central spicule short and narrow; setal (scales) coverage of the apical plate sparse (1–25%); size of left setose flange small; size of right setose flange large. Left paramere basal lobe ovate (Fig. 47 LP), short slope to arm; arm short and broad, terminal lobe indistinct but abruptly narrowed at terminus, apical tuft of long setae, medium-lengthed setae extended along apical ¾ of ventral edge (Fig. 47 LP); ventral edge slightly curved. Right paramere narrowly triangular with an apical tuft of long setae, medium-lengthed setae extended along apical ¾ of ventral edge (Fig. 47 RP).
Female genitalia: Basal gonocoxite 1 short and narrow, flattened apically, ventral surface smooth, internal dorso-lateral carina with 2 setae. Gonocoxite 2 (Fig. 5) narrowly elongated, a bluntly rounded triangle, apically reflexed. Ramus short and broad.
Comments: Mecodema pluto was described by Britton (1949) from one badly damaged specimen, and even though the type locality is Mt Te Aroha, specimens are more easily collected in Kauaeranga Valley, Coromandel.
Distribution: New Zealand, North Island, southern Coromandel Range and northern Kaimai Range.
Holotype: BMNH labelled [card mounted]. Te Aroha Trig. Stn. 1001. [hw] Type [round label with red border] glued on card / 1200 [light blue label glued on card] / Te Aroha N. Zealand. H. Swale. 1913–117. [broad pink line below collector name] / HOLOTYPE Mecodema pluto n. sp. [hw] E. B. Britton det. 6.11.1945 [hw].
Paratypes: (see Seldon & Leschen 2011).
Material examined: 1♀, NEW ZEALAND CL Kennedy Block Sce Res 28.XII.1993 – 2.I.1994 Larivière. Larochelle / Moist for (tree fern-nikau-Phyllocladus) Stony soil. Pit traps (NZAC); 2♂, NEW ZEALAND, CL, Coromandel Range, Kauaeranga Valley, Trestle View camp PTs 19 Oct–5 Nov 2010, D.S. Seldon DSS043 / CAR 074 (AMNZ); 1♂, NEW ZEALAND BP Te Aroha Forest Park, Tui Ridge Summit Track, S37°31.4718, E175°43.9158, A. Seago / U.C. Berkeley EMEC 205,853 / CAR 055 (UCBC); 1♀, NEW ZEALAND CL Maumaupaki Track 800m 8.XI–6.XII.1993 Larivière. Larochelle / Moist for. (tawa-supplejack- Coprosma) Rich litter Pit traps (NZAC).
description: Published as part of Seldon, David S. & Buckley, Thomas R., 2019, The genus Mecodema Blanchard 1853 (Coleoptera: Carabidae: Broscini) from the North Island, New Zealand, pp. 1-148 in Zootaxa 4598 (1) on pages 92-94, DOI: 10.11646/zootaxa.4598.1.1, http://zenodo.org/record/2668063