Mecodema tewhara, Seldon & Buckley, 2019

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 : 121-123

Mecodema tewhara sp. n.

Figure 59 .

Diagnosis: Distinguished from other Mecodema species by: 1, supraorbital puncture large bearing 6–8 setae; 2, supraorbital grooves indistinct or absent; 3, the prothoracic carina broad the entire length, slightly crenulated with 10–14 setae each side; 4, distribution of setae along the ventral edge of the left paramere ( Fig. 59 LP).

Description: Length 27–32 mm, pronotal width 7.5–9 mm, elytral width 9–10.5 mm. Colour of entire body matte to glossy black, coxae red to dark reddish-brown, legs dark brown to matte black.

Head: Broad and flat ( Fig. 14A ). Vertex with several scattered obsolescent punctures posterad vertexal groove ( Fig. 59 ); vertexal groove well-defined by punctures along the entire length, deep and broad laterally; large supraorbital puncture bearing 6–8 setae, supraorbital grooves indistinct or absent; frons with a large and shallow depression each side of midline; frontoclypeal suture very narrow, tentorial pits indistinct each within a large depression; anterior area of clypeus medially convex with lateral ridges, mesad lateral setose punctures; clypeus with 3 very distinct and deep setose punctures ( Fig. 59 ): 1 each side and 1 medially (medial puncture maybe absent) bearing 2–3 setae. Labrum rectangular, anterior edge straight but rounded laterally, slightly emarginated medially with 2 proximate central setae, 2 setae each side evenly spaced (all setae very long). Mentum lobes rounded ( Fig. 12F ), median process very short and broad, moderately angled upward (30°), weakly indentate ( Fig. 12C ); mentum setae absent. Submentum sclerite constriction narrow with 6–8 setae (medial pair proximate). Stipes with 2 basal setae. Gula pits small within a larger depression, suture narrow and indistinct, gula flat and smooth. Gena ( Fig. 8 ) with fine lines forming an isodiametric pattern over entire area.

Prothorax: Prothoracic carina broad the entire length, slightly crenulated with 10–14 setae each side ( Fig. 59 ), extended beyond anterior angle; posterior lateral sinuation evidently carinate, parallel; pronotum broad and flattened, overall shape cordate ( Fig. 59 ), anterior lateral margin of pronotum distinctly inwardly curved; midline well-defined, anterior medial triangular impression and posterior medial diamond-shaped impression present, a shallow circular depression posterad anterior lateral margin; disc with fine lateral wrinkles ( Fig. 59 ); pronotal foveae deep and narrow; anterior edge slightly inwardly curved, posterior edge relatively straight (may be slightly inwardly curved medially). Prosternum ( Fig. 2 ) flat, may have fine transverse wrinkles laterally forming an isodiametric pattern; proepisternum without microsculpture. Procoxal setae absent; protibia distally expanded and shovel-like ( Fig. 10B ).

Elytra: Relatively narrow the entire length, especially posteriorly; humeral angle anteriorly covergent ( Fig. 6A ); basal margin slightly curved (distinctly abrupt) and bevelled to base, intervals and striae truncated ( Fig. 59 ), except interval 1 extended to scutellum; lateral carina narrow the entire length, extended to humeral angle; humerus with 2 setose punctures very proximate end of carina ( Fig. 59 ), 3 rd double-spaced posterad from 2 nd and 4 th doublespaced posterad from 3 rd (4 in total); suture defined and continues to scutellum; all striae relatively indistinct with shallow indentations, increasd slightly in size laterally; intervals 1–4 flat, intervals 5–8 slightly increased convexity, interval microsculpture absent; 7 th strial setal pattern with 3–4 setose punctures in anterior ½, 5 setose punctures in posterior ½ ( Fig. 59 ), setose punctures small.

Ventral surface: Mesepisternum without microsculpture; metepisternum may be very finely micropunctate; setose punctures present on mesocoxa (2) and metacoxa (2); Abdominal ventrites 1 and 2 ( Fig. 2 ) with scattered obsolescent pitting; ventrites 3–5 with 1 setose puncture each side of midline; ventrite 6 setae present: ♂ with 1 setose puncture each side distantly spaced on straight apical edge, ♀ with 2–3 setose punctures each side proximate midline of rounded apical edge; lateral foveae absent. Anterior metaventrite process ( Fig. 2 ) a short triangle with carina moderately broad apically, laterally narrowed.

Male genitalia: Apical portion of penis lobe asymmetrically hooked with a moderate deflection to right of vertical axis (VV) ( Fig. 15B ); ventral process a short, very bluntly, rounded point, apex with a symmetrically flattened curve upward to form a short and rounded dorsal process without recurve, then briefly curved to shaft ( Fig. 59 PL); ventral edge of penis lobe with moderate curve to right (VV); shaft of penis lobe narrow apically but gradually broadened toward base; overall length of penis lobe moderately curved ventrally (LV) ( Fig. 16B ). Structures of the endophallus ( Fig. 4 ): laterally form of the apex of the central spicule flattened; dorsal form of the apex of the central spicule greatly expanded with projection; setal (scales) coverage of the apical plate sparse (1–25%); size of left setose flange small; size of right setose flange very long. Left paramere narrowly rectangular with slight dorsal hump forming a moderate (45°) slope to arm; arm short and narrow ( Fig. 59 LP); terminal lobe short and broad with an apical tuft of a few very short setae; comb of sparse long setae at arm-basal lobe junction ( Fig. 59 LP); ventral edge straight. Right paramere long, very narrow and triangular with a double row of long to medium-lengthed setae extended along apical ¾ of ventral edge ( Fig. 59 RP).

Female genitalia: Basal gonocoxite 1 ( Fig. 5 ) short and broad, ventral surface with a few rugose wrinkles, internal dorso-lateral carina with 1 seta. Gonocoxite 2 ovate with apical edge curved upward. Ramus short and narrow, slightly curved dorsally.

Comments: Mecodema tewhara ( spiniferum species group) inhabits the edges of regenerating scrubland and semi-mature coastal broadleaf forest on the north and eastern areas of Bream Head and Mt Lion, Whangarei. It shares these forests with M. manaia ( curvidens species group), which prefers the more mature forest with a higher canopy cover and thicker leaf litter. This species may be predicted to inhabit Mt Manaia with M. manaia , but as yet no specimens of M. tewhara have been collected from that locality.

Distribution: New Zealand, North Island, Northland, Bream Head and Mt Lion (Whangarei).

Holotype: NZAC male labelled. NEW ZEALAND, ND, Whangarei , Bream Head, Trap 20, 20 Apr 2011 P. Mitchell (DoC) / HOLOTYPE Mecodema tewhara n. sp. design. DS Seldon, TR Buckley 2018 [red label].

Paratypes: 1♀, NEW ZEALAND, ND, Whangarei , Bream Head, 24 Apr 2011 P. Mitchell (DoC) ( NZAC); 4, NEW ZEALAND, ND, Whangarei, Bream Head, Trap 19, 24 Nov 2010, P. Mitchell (DoC) ( NZAC) .

Etymology: This species is named for Te Whara, who was the principle wife of the rangatira Manaia, which is fitting as the other species found on Bream Head is Mecodema manaia .

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 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 59. Mecodema tewhara 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.