Mecodema tenaki Seldon & Leschen, 2011

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 : 114-116

Mecodema tenaki Seldon & Leschen, 2011 .

Figure 56 .

Diagnosis: Differs from other North Island Mecodema species by having: 1, pronotal carina with 4-6 setae along each side ( curvidens species group); 2, pronotal carina smooth; 3, pronotal disc with a small depression each side anterad pronotal foveae; 4, shape of the basal lobe and setal distribution of the left paramere ( Fig. 56 LP).

Description: Length 23.6–27 mm, pronotal width 6.4–7.4 mm, elytral width 7.4–8.5 mm. Colour of entire dorsal body glossy black, entire ventral body matte black.

Head: Broad and flat ( Fig. 14A ). Vertex smooth; vertexal groove narrow, defined entire length with V-shape medially ( Fig. 56 ); large supraorbital puncture bearing 3 setae; 2 shallow supraorbital grooves; frons smooth with a large and very shallow depression each side of midline; frontoclypeal suture ( Fig. 9 ) indistinct, except laterally where it meets deep tentorial pits; anterior area of clypeus with indistinct or without microsculpture; clypeus with 1 large setose puncture on each side bearing 2–3 setae ( Fig. 56 ). Labrum rounded, anterior edge outwardly curved with 2 proximate central setae, 2 setae each side evenly spaced. Mentum lobes squared ( Fig. 12G ), median process very short and broad, slightly angled upward (15°), strongly indentate ( Fig. 12A ); setose punctures present. Submentum sclerite constriction narrow with 4–6 setae clustered laterally. Stipes with 2 basal setae. Gula pits large within defined suture, gula ( Fig. 8 ) weakly convex with very fine and closely packed transverse wrinkles. Gena with well-defined isodiametric pattern across entire area.

Prothorax: Prothoracic carina narrow the entire length, slightly crenulated with 4–6 setae each side ( Fig. 56 ), extended beyond anterior angle; posterior lateral sinuation indistinctly carinate, slightly angled inward; pronotum broad and flattened but deflected to carina, overall shape cordate ( Fig. 56 ); midline well-defined, fine transverse wrinkles may be present laterally on disc, small shallow dents present either side of midline; pronotal foveae deep and narrow; anterior edge slightly inwardly curved, posterior edge straight, slightly emarginated medially. Prosternum flat with fine, evenly spaced, transverse lines; proepisternum without microsculpture. Procoxal ( Fig. 2 ) setae absent; protibia distally expanded and shovel-like ( Fig. 10B ).

Elytra: Broad and flattened but deflected to carina; humeral angle anteriorly convergent ( Fig. 6A ); basal margin sharply angled ( Fig. 56 ) and bevelled to base, interval 1 extended to scutellum, other intervals and striae truncated at margin; humerus with 1–2 setose punctures ( Fig. 56 ); lateral carina ( Fig. 11 ) narrow the entire length, extended to humeral angle; suture well-defined; striae with small, regularly distributed, asetose punctures; intervals weakly convex; interval microsculpture absent; 7 th strial setal pattern with 0–1 setose punctures in anterior ½, 3–4 evenly spaced setose punctures in posterior ½ ( Fig. 56 ), setose punctures small.

Ventral surface: Mesepisternum with rugose wrinkles; metepisternum without microsculpture; setose punctures present on mesocoxae (1) and metacoxae (1). All abdominal ventrites ( Fig. 2 ) wrinkled laterally; ventrites 1–3 without setose punctures, ventrites 4 and 5 setose punctures present (1–2) each side of midline; lateral foveae absent; ventrite 6 setae present: ♂ with 2–4 setose punctures each side of midline, apical edge straight, ♀ with 2–4 setose punctures each side of midline, apical edge bluntly pointed. Anterior metaventrite process ( Fig. 2 ) an apically broad triangle with carina poorly defined apically, narrowed posterad.

Male genitalia: Apical portion of penis lobe symmetrically rounded ( Fig. 56 PL) with a slight deflection to right of vertical axis (VV) ( Fig. 15C ); ventral edge of penis lobe straight (VV); overall length of shaft penis lobe broad and short, 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; seta (scales) coverage of the apical plate moderate (26–75%); size of left setose flange small; size of right setose flange large. Left paramere basal lobe ovate, narrowed slightly toward arm ( Fig. 56 LP), short slope to arm; arm long and broad, narrowed to indistinct terminal lobe; apical tuft of sparse, medium-lengthed setae; setae extended along apical ¾ of ventral edge ( Fig. 56 LP), ventral edge curved. Right paramere narrowly rectangular, gradually narrowed to terminus with setae extended along apical ¾ of ventral edge ( Fig. 56 RP).

Female genitalia: Basal gonocoxite 1 ( Fig. 5 ) short and broad, ventral surface with a few longitudinal grooves, internal dorso-lateral carina with 2 setae. Gonocoxite 2 a short, rounded triangle with apical edge slightly reflexed. Ramus long and narrow.

Comments: Mecodema tenaki has a very limited range, residing in degraded native kanuka ( Kunzea robusta )- broadleaf forest patches in the North Cape to Cape Reinga areas.

Distribution: New Zealand, North Island, Northland, restricted to the Cape Reinga to North Cape area (see Ball et al. 2013).

Holotype: NZAC male labelled. NEW ZEALAND ND Cape Reinga Te Paki RBB-7 13 Nov 2006 O. Ball / HOLOTYPE Mecodema tenaki n. sp. design. by Seldon & Leschen 2010 [red label].

Paratypes: (see Seldon & Leschen 2011).

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 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 8. Detail of the ventral head with the taxonomic structures used in the species descriptions. SBMS = submentum setae; SBM = submentum sclerite; ML = mentum lobe; MP = mentum process (with indentation); MPW = mentum process width; SBS = stipes basal setae; MPL = mentum process length; MPS = mentum process setae; SBMC = submentum sclerite constriction; GP = gula pits; GS = gula suture.

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 11. Detail of pronotum showing the taxonomic structures used in the species descriptions. PPC = posterior pronotum constriction; PS = pronotal setae; PAA = pronotum anterior angle; AE = anterior edge; PC = pronotal carina; ML = midline; PF= pronotal foveae; PPS = pronotum posterior sinuation; PE = posterior edge.

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 56. Mecodema tenaki 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.