Mecodema tuhoe, 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 : 126-128

Mecodema tuhoe sp. n.

Figure 61 .

Diagnosis: Distinguishable from other North Island Mecodema species by: 1, elytral intervals 1–6 slightly convex, intervals 7–9 strongly convex; 2, distinctive shape of the apical portion of the penis lobe ( Fig. 61 PL).

Description: Length 25.5–31.8 mm, pronotal width 6.9–8.8 mm, elytral width 7.8–9.7 mm. Colour of entire body matte to glossy black, coxae may be dark reddish-brown.

Head: Broad and flat ( Fig. 14A ). Vertex with very fine wrinkles forming an isodiametric pattern laterally; vertexal groove defined by punctures and small grooves, broadened laterally ( Fig. 61 ); small supraorbital puncture bearing 4–5 setae; 3 well-defined supraorbital grooves; frons with a large and shallow depression each side of midline, otherwise smooth; frontoclypeal suture and tentorial pits ( Fig. 9 ) indistinct; anterior area of clypeus with narrow grooves laterally, broad scoop-like depression medially, 1 setose puncture each side and 1 medial setose puncture, all bearing 2 setae (medial puncture may be absent) ( Fig. 61 ). Labrum rectangular, apical edge moderately emarginated with 2 proximate central setae, 2 setae each side evenly spaced. Mentum lobes rounded ( Fig. 12F ), median process broad and short, moderately angled upward (30°), moderately indentate ( Fig. 12B ); mentum setae absent. Submentum sclerite ( Fig. 8 ) constriction narrow with 6 evenly-spaced setae (large gap medially). Stipes with 2 basal setae. Gula pits small and deep, suture indistinct, gula flat and smooth. Gena with rugose wrinkles forming an isodiametric pattern across entire area.

Prothorax: Prothoracic carina narrow the entire length, crenulations absent with 10–14 setae each side ( Fig. 61 ), extended to anterior angle; posterior lateral sinuation evidently carinate, slightly angled outward; pronotum broad and laterally deflected, overall shape cordate; midline well-defined, anterior medial and posterior medial diamond-shaped impressions present, disc with fine wrinkles present (may only be laterally) ( Fig. 61 ); pronotal foveae broad and shallow; anterior edge inwardly curved, posterior edge straight. Prosternum flat and smooth; proepisternum without microsculpture. Procoxal setae absent; protibia distally expanded and shovel-like ( Fig. 10B ).

Elytra: Broad and deflected laterally, posteriorly steep to apex; humeral angle evenly convex ( Fig. 6B ), basal margin slightly curved and gently sloped to base, interval 1 extended to scutellum; lateral carina narrow the entire length, extended beyond humerus; humerus with 3–4 setose punctures ( Fig. 61 ); suture poorly defined; striae impressed with regularly spaced asetose punctures, striae 7 and 8 with slightly larger asetose punctures; intervals 1–6 weakly convex, intervals 7–9 strongly convex; interval microsculpture present as fine transverse lines; 7 th strial setal pattern with 3–4 setose punctures in anterior ½, 3–4 setose punctures in posterior ½, setose punctures small.

Ventral surface: Mesepisternum ( Fig. 2 ) with numerous obsolescent punctures; metepisternum without microsculpture (may have wrinkles); setose punctures present on mesocoxae (1) and metacoxae (2). All abdominal ventrites finely lineate laterally, ventrites 1 and 2 with numerous obsolescent punctures; ventrites 3–5 with 1 setose puncture each side of midline; ventrite 6 setae present: ♂ with 1 setose puncture each side at junction of straight apical edge and curve anterad, ♀ with 2 setose punctures each side, apical edge rounded; ventrites foveate laterally (shallow). Anterior metaventrite process ( Fig. 2 ) a rounded triangle with the carina well-defined, broad anterad and narrowed posterad.

Male genitalia: Apical portion of penis lobe asymmetrically rounded with a distinct deflection to right of vertical axis (VV) ( Fig. 15A ); shaft curved down to form bluntly rounded point of the ventral process, apex symmetrically curved upward to form a continuous curving dorsal process (flattened discus-shaped), that terminates with sharp curve to shaft ( Fig. 61 PL); ventral edge of penis lobe moderately curved to right (VV); penis lobe shaft narrow the entire length; 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 greatly expanded without 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 articulated at right angle to penis lobe, small and rectangular with a slight dorsal hump forming a moderate (45°) slope to arm; arm very short and broad ( Fig. 61 LP); terminal lobe short and broad, apical tuft of a few short setae and short, sparsely distributed setae at arm-basal lobe junction ( Fig. 61 LP); ventral edge curved. Right paramere long, broadly rectangular ( Fig. 61 RP), gradually narrowed from ½ length to terminus with a double row of long to medium-lengthed setae extended along apical ½ of ventral edge.

Female genitalia: Basal gonocoxite 1 long and broad, ventral surface with many rugose grooves, internal dorso-lateral carina with 3 setae. Gonocoxite 2 paddle-like and ovate in shape with apical edge strongly curved upward. Ramus ( Fig. 5 ) long and broad.

Comments: This species appears very much like M. simplex , and the dorsal external morphology confirms this conflation. However, the aedeagus of M. tuhoe , including the parameres are completely different in shape than those structures in M. simplex .

Distribution: New Zealand, North Island, Bay of Plenty, Ruatahuna, Kakanui River.

Holotype: LUNZ male labelled. NEW ZEALAND, GB, Kakanui 200m NZMS260 Z14-886818, 1.II.1993, J.S. Dugdale, R.M. Emberson / under log in puriri ( Vitex lucens )-nikau forest / EAST CAPE INSECT SURVEY 1992- 93 / HOLOTYPE Mecodema tuhoe n. sp. design. DS Seldon, TR Buckley 2018 [red label] / LUNZ00002675 .

Paratypes: 1♀, NEW ZEALAND, GB Kakanui 300m 2 Dec 1992 – 1 Feb 1993 R.C. Henderson / Pit trap / NZAC04004857 ; 1, NEW ZEALAND, GB Kakanui 22 Sep 1992 G.M. Barker ( NZAC) ; 1♂, 1♀ NEW ZEALAND, GB Kakanui 27 Oct–2 Dec 1992 G. Hall / Pit trap ( NZAC) ; 1♀, NEW ZEALAND, GB Kakanui 300m 15 Mar–30 Apr 1993 / J.S. Dugdale Pit traps ( NZAC) .

Etymology: Mecodema tuhoe is named after Ngati Tūhoe whose rohe includes Te Urewera.

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 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 61. Mecodema tuhoe 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.