Mecodema kokoromatua Seldon, Leschen & Liebherr, 2012

Seldon, David S. & Buckley, Thomas R., 2019, The genus Mecodema Blanchard 1853 (Coleoptera: Carabidae: Broscini) from the North Island, New Zealand, Zootaxa 4598 (1), pp. 1-148 : 65-67

Mecodema kokoromatua Seldon, Leschen & Liebherr, 2012 .

Figure 35 .

Diagnosis: Differs from other North Island Mecodema species due to having: 1, less than or equal to six setae along the pronotal carina ( curvidens species group); 2, mesocoxa and metacoxa with setose punctures absent; 3, the shape of the left paramere basal lobe is a small and very narrowly rectangular with a short slope to arm, terminal lobe with tuft of medium length setae ( Fig. 35 PL).

Description: Length 22–25 mm, pronotal width 4–4.5 mm, elytral width 5–5.5 mm. Colour of entire body matte to glossy black, coxae may be dark reddish-brown.

Head: Narrow and flat ( Fig. 14C ). Vertex smooth; vertexal groove narrow and well-defined, posteriorly curved medially; large supraorbital puncture ( Fig. 9 ) bearing 2–3 setae; 2 defined supraorbital grooves; frons with a small and shallow depression either side of midline; frontoclypeal suture straight, very narrow and well defined between small tentorial pits; anterior clypeal microsculpture indistinct, 1 large setose puncture each side bearing 2 setae. Labrum ( Fig. 9 ) rectangular, anterior edge outwardly curved with 2 proximate central setae, 2 each side evenly spaced. Mentum lobes squared ( Fig. 12G ), median process long and narrow, slightly angled upward (15°), indentation notched ( Fig. 12D ); mentum setae variably present or absent. Submentum sclerite constriction narrow bearing 6–8 evenly spaced setae. Stipes with 2 basal setae. Gula pits broad and deep, gula suture well-defined, gula flat and smooth. Gena with fine wrinkles forming an isodiametric pattern across entire area.

Prothorax: Prothoracic carina very narrow the entire length, crenulations absent with 4–6 setae each side ( Fig. 35 ), extended to anterior angle; posterior lateral sinuation evidently carinate, angled slightly inward; pronotum narrow, medially flattened but deflected laterally, overall shape squared ( Fig. 35 ); midline well-defined without medial impressions, disc with fine, transverse lines from midline to laterally, pronotal foveae narrow and shallow; anterior edge slightly curved to straight, posterior edge curved medially. Prosternum weakly convex with very fine transverse lines present; proepisternum dorso-ventrally wrinkled. Procoxal setae absent; protibia distally expanded and shovel-like ( Fig. 10B ).

Elytra: Narrow and flat to moderately deflected laterally; humeral angle evenly convex ( Fig. 6B ); basal margin slightly curved and bevelled to base, interval 1 extended to scutellum; lateral carina narrow the entire length, extended beyond humeral angle; humerus with 3 proximate setose punctures along angle, 1 double-spaced posterad; suture impressed but no more so than striae; striae with regularly spaced asetose punctures that increased in size laterally; intervals 1–6 flat or weakly convex, intervals 7–9 weakly convex; interval microsculpture absent; 7 th strial setal pattern with 1 setose puncture in anterior ½, 3–4 setose punctures in posterior ½ ( Fig. 35 ), setose punctures small.

Ventral surface: Mesepisternum ( Fig. 2 ) wrinkled; metepisternum without microsculpture; setose punctures absent on mesocoxae and metacoxae. Abdominal ventrites 1 and 2 without microsculpture and punctures; ventrites 3 and 4 setose punctures absent, ventrite 5 with 1 setose puncture each side of midline; ventrite 6 ( Fig. 2 ) setae present: ♂ with 3 setae each side, apical edge obtusely rounded, ♀ with 2 setae each side of midline, apical edge a flattened curve; ventrites 3–5 foveate laterally (very shallow, almost indistinct). Anterior metaventrite process a bluntly rounded triangle with a well-defined and broad carina the entire length.

Male genitalia: Apical portion of penis lobe symmetrically rounded ( Fig. 35 PL) with a distinct deflection to right of vertical axis (VV) ( Fig. 15A ); apex with dorsal curve slightly pushed forward of vertical axis ( Fig. 3 ); shaft of penis lobe straight (VV), greatly broadened toward base; 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 pointed; dorsal form of the apex of the central spicule narrow and short; setal (scales) coverage of the apical plate extensive (76–100%); size of left setose flange small; size of right setose flange large. Left paramere basal lobe small and very narrowly rectangular with a short slope to arm ( Fig. 35 LP); arm long (nearly equal to basal lobe); terminal lobe indistinct from arm, apical tuft of medium-lengthed setae, with very short, sparse setae extended along apical ½ of ventral edge ( Fig. 35 LP). Right paramere similar in size and shape to left with a double-row of medium length setae extended along apical ¾ of ventral edge ( Fig. 35 RP).

Female genitalia: Basal gonocoxite 1 narrow at base, width doubled apically, internal dorso-lateral carina with 2 apical setae, ventral surface entirely covered with grooves. Gonocoxite 2 ( Fig. 5 ) paddle-like, ventral surface convex with sensillar pits. Ramus long and narrow, broadened apically.

Comments: Mecodema kokoromatua is restricted to coastal sand dune forest at the base of the Ahipara Escarpment. Distribution: New Zealand , North Island , Northland, Herekino , North Head, Waiatua Stream. Holotype: NZAC male labelled. NEW ZEALAND, ND, Herekino, North Head, Waiatua Stream, 8–23 Dec 2010. D.S. Seldon, 35°16’11.052S, 173°09’35.314E / HOLOTYPE Mecodema kokoromatua sp.n. design. Seldon, Leschen & Liebherr 2011 [red label]. Paratypes: (see Seldon et al. 2012).

Figures

FIGURE 2. Ventral view of a Mecodema specimen showing specific morphological structures, excluding taxonomic structures indicated in detail figures, used in the species descriptions. ƑLF = ventrite lateral foveae; ƑSP = ventrite setose punctures; MTC = metacoxa; MTƑP = metaventrite process; MSC = mesocoxa; PC = procoxa; PS = prosternum; G = gena; PES = proepisternum; MSE = mesepisternum; MTE = metepisternum; Ƒ1–Ƒ6 = ventrites 1-6 (ventrites 1-3 may be fused); M = midline (dashed line, not a taxonomic structure).

FIGURE 3. Detail of the apical portion of aedeagus (male genitalia) with parameres removed showing taxonomic structures, vertical and horizontal planes that are referred to in the species descriptions and redescriptions: aedeagus shaft width (ASW); vertical central line (ƑCL) [dashed line, not a structure]; horizontal central line (HCL) [dashed line, not a structure].

FIGURE 4. An Environmental Scanning Electron Microscope (ESEM) photograph of the four main structures of the apical plate of the endophallus within the penis lobe. This is an example from Mecodema haunoho showing the central spicule (c.s), left (l.s.f) and the right setose flange (r.s.f), and microtrichial field (m.f). These structures are variable among species but within a species, they are very consistent, even over distant geographical ranges. The microtrichial field can be covered in flattened scales as in photo above, or with elongated setae-like scales.

FIGURE 5. The entire female reproductive tract (ventral view) including taxonomic structures (for all other abbreviated structure names see Seldon et al. 2012). However, for this revision only the following structures are important: HS = helminthoid sclerite; G1 = gonocoxite 1; G2 = gonocoxite 2; TDC = transverse dorsal carina; R = ramus.

FIGURE 6. Detail of the three different forms of the elytral humeral angle: (A) = anteriorly convergent (M. parataiko), (B) = evenly convex (M. oconnori), (C) = subangulate (M. atuanui).

FIGURE 9. Dorsal view of head with detail of the morphological structures used in the species descriptions. Ƒ = vertex; SPS = supraorbital puncture setae; SP = supraorbital puncture; F = frons area; FCS = frontoclypeal suture; C = clypeus; M = mandible; LS = labrum setae; L = labrum; ACM = anterior clypeal microsculpture; CSP = clypeal setose puncture; TP = tentorial pit; SG = supraorbital grooves; E = eye; ƑG = vertexal groove.

FIGURE 10. The protibia form is a character used mainly to determine between genera, except for one species in Mecodema where the difference between (A) greatly distally expanded (M. antarctica) and (B) expanded distally (all other Mecodema species) is used.

FIGURE 12. Ventral view of the mentum with a number of different character states. Illustrations A–D are the different forms of the indentation in the apex of the median process: (A) distinctly indentate (M. manaia); (B) moderately indentate (M. pluto); (C) slightly indentate (M. infimate); (D) indentation notched (M. parataiko). Illustrations E–G are the three general forms (i.e., hashed lines) of the mentum lobes: (E) triangular; (F) rounded; (G) squared.

FIGURE 14. Diagrammatic cross sections that represent the width and convexity of head or deflection of pronotum (frontal view): (A) broad and flat; (B) broad and convex; (C) narrow and flat; (D) narrow and convex.

FIGURE 15. The penis lobe in ventral view showing the relative deflection to right of vertical: (A) distinctly deflected (M. regulus); (B) moderately deflected (M. haunoho); (C) slightly deflected (M. oregoides). Scale bars = 1 mm. Structures of penis lobe indicated are: base (B); lateral edge (LE); apical portion (AP); ventral edge (ƑE).

FIGURE 16. Relative strength of the ventral curve over the length of the penis lobe (lateral view): (A) slightly curved (M. oblongum); (B) moderately curved (M. ponaiti); (C) distinctly curved (M. manaia). Scale bar = 1 mm.

FIGURE 35. Mecodema kokoromatua plate with half habitus (left) and the three (detached) structures of the male aedeagus: the right (RP) and left parameres (LP), plus the penis lobe (PL). The bottom scale bar is the width across the widest point of the pronotum of the specimen used for this habitus and top scale bar equates to the half the length of the penis lobe.