Mecodema wharekahika, 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 : 133-136

Mecodema wharekahika sp. n.

Figure 64 .

Diagnosis: Distinguished from other North Island Mecodema species by having: 1, vertexal groove narrow and shallow the entire length, defined by punctures and short grooves; 2, prothoracic carina broad in anterior ⅓, narrowed in posterior ¾, crenulations absent with 10–12 setae each side; 3, shape of the basal lobe and setal distribution along the ventral edge of the left paramere ( Fig. 64 LP).

Description: Length 28.3–33 mm, pronotal width 7.6–9.3 mm, elytral width 8.7–10.3 mm. Colour of body dorsally matte to glossy black, ventrally dark reddish-brown to matte black, coxae and femur dark red, legs black.

Head: Broad and flat ( Fig. 14A ). Vertex ( Fig. 9 ) with a fine isodiametric pattern laterally; vertexal groove narrow and shallow the entire length, defined by short grooves and punctures, increased laterally; large supraorbital puncture bearing 4–5 setae ( Fig. 64 ); 2–3 defined supraorbital grooves; frons with a large shallow depression each side of midline; frontoclypeal suture narrow between small tentorial pits; anterior area of clypeus grooved, 1 large setose puncture each side and a medial setose puncture, all bearing 2 setae each ( Fig. 64 ). Labrum rounded, anterior edge outwardly curved, weakly emarginated with 2 proximate central setae, 2 setae each side evenly spaced. Mentum lobes rounded ( Fig. 12F ), mentum process very short and broad, moderately angled upward (45°), strongly indentate ( Fig. 12A ); mentum setae absent. Submentum sclerite constriction broad with 6 even-spaced setae (broad gap medially). Stipes with 2 basal setae. Gula pits small, suture indistinct, gula weakly convex with fine transverse lines. Gena with fine wrinkles forming an isodiametric pattern anterad.

Prothorax: Prothoracic carina broad in anterior ⅓, narrowed in posterior ¾, crenulations absent with 10–12 setae each side ( Fig. 64 ), extended beyond anterior angle; posterior lateral sinuation indistinctly carinate, slightly angled outward; pronotum broad and flat, slightly deflected laterally, overall shape cordate ( Fig. 64 ); midline welldefined, anterior medial triangular impression and posterior medial diamond-shaped impression present, disc with fine wrinkles laterally and a small round depression each side midway; pronotal foveae ( Fig. 11 ) very broad and shallow; anterior edge and posterior edge slightly inwardly curved. Prosternum ( Fig. 2 ) concave and smooth; proepisternum with fine wrinkles. Procoxal setae absent; protibia distally expanded and shovel-like ( Fig. 10B ).

Elytra: Broad and flat, deflected laterally; humeral angle evenly convex ( Fig. 6B ); basal margin slightly curved and gently sloped to base, interval 1 extended to base; lateral carina narrow the entire length, extended beyond humeral angle; humerus with 4 setae: 3 proximate the angle, 1 double-spaced posterad ( Fig. 64 ); suture indistinct; striae with small, regularly spaced, asetose punctures, increased in size laterally; intervals 1–8 weakly convex, interval 9 moderately convex; interval microsculpture present as well-defined transverse lines; 7 th strial setal pattern with 3–4 setose punctures in anterior ½, 4 setose punctures in posterior ½ ( Fig. 64 ), setose punctures large.

Ventral surface: Mesepisternum with wrinkles, may have sparse obsolescent punctures; metepisternum ( Fig. 2 ) finely lineate; setose punctures present on mesocoxa (2) and metacoxa (2). All abdominal ventrites lineate across entire area; ventrites 3–5 with 1 setose puncture each side of midline; ventrite 6 setae present: ♂ with 1 setose puncture situated distantly at junction of straight apical edge and curve anterad, ♀ with 3 setose punctures each side (1 proximate midline, other 2 at junction of straight apical edge and curve anterad); ventrites foveate laterally. Anterior metaventrite process ( Fig. 2 ) a short, pointed triangle (convex basally) with a broad carina the entire length.

Male genitalia: Apical portion of penis lobe asymmetrically hooked with a distinct deflection to right of vertical axis (VV) ( Fig. 15A ); ventral edge of shaft curved sharply downward to form a short and pointed ventral process that is slightly back from vertical axis ( Fig. 64 PL), apex curved symmetrically upward to form a very rounded and flattened dorsal process with a brief, straight angle back to the shaft ( Fig. 64 PL); shaft of penis lobe straight and narrow the entire length (VV); overall length of penis lobe moderately curved ventrally (LV) ( Fig. 16B ). Structures of the endophallus ( Fig. 4 ): lateral 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 extensive (76–100%); size of left setose flange small; size of right setose flange absent. Left paramere basal lobe triangular due to large dorsal hump forming steep (60°) slope to arm ( Fig. 64 LP); arm short and narrow, ventral edge with sharp curve upward; terminal lobe indistinct from arm, apical tuft of sparse short setae ( Fig. 64 LP), very few short setae along ventral edge to longer setal comb in arm-basal lobe junction; ventral edge straight. Right paramere narrowly rectangular, gradually narrowed to terminus with setae extended along apical ½ of ventral edge ( Fig. 64 RP), strongly inwardly curved apically across penis lobe.

Female genitalia: Basal gonocoxite 1 short and broad especially apically, ventral surface with numerous rugose wrinkles, internal dorso-lateral carina ( Fig. 5 ) with 2 setae. Gonocoxite 2 short, bluntly rounded triangular (shark-fin like) with slight recurve of apical edge. Ramus long and broad.

Comments: Mecodema wharekahika is found in coastal podocarp-broadleaf forest, but it is not known if its range extends beyond Te Koau.

Distribution: New Zealand, North Island, East Cape region, Te Koau-Hicks Bay.

Holotype: NZAC male labelled. NEW ZEALAND BP Te Koau 243m 31 Jan–15 Mar 1993 R.C. Henderson / Pit trap / HOLOTYPE Mecodema wharekahika design. DS Seldon, TR Buckley 2018 [red label].

Paratypes: 1♀, NEW ZEALAND, BP Te Koau 243m 1 Dec 1992 – 31 Jan 1993 R.C. Henderson / Pit trap ( NZAC) ; 1♂, NEW ZEALAND, BP Te Koau 243m 31 Jan–15 Mar 1993 R.C. Henderson / Pit trap ( NZAC) ; 1♂, NEW ZEALAND, BP Te Koau ‘ Twin Puriris’ 31 Jan – 15 Mar 1993 / R.C. Henderson Pit traps ( NZAC) ; 1♂ NEW ZEALAND, BP Te Koau 243m 15 Mar–28 Apr 1993 / J.S. Dugdale Pit traps ( NZAC) ; 1♂, NEW ZEALAND, BP Te Koau 243m 30 Oct 1992 J.S. Dugdale / Pit trap ( NZAC) ; 1♂, NEW ZEALAND, BP Te Koau 26 Oct–1 Dec 1992 G. Hall / Pit trap / NZAC04004855 ; 1♂, NEW ZEALAND, BP Te Koau 26 Oct–1 Dec 1992 G. Hall / Pit trap ( NZAC) ; 1, NEW ZEALAND GB Te Koau 23 Sep 1992 G.M. Barker 100 m Puriri /nikau Forest [hw] ( NZAC) .

Etymology: This species, Mecodema wharekahika , has been given the Māori name for Hick’s Bay, as it is found in the native coastal broadleaf forest above the bay.

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 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 64. Mecodema wharekahika 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.