Mecodema genesispotini, 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 : 48-51

Mecodema genesispotini sp. n.

Figure 28 .

Diagnosis: Distinguished from other North Island Mecodema species by having: 1, a vertexal groove defined by punctures and short rugose wrinkles entire length; 2, pronotum carina smooth with 8–10 setae; 3, pronotum with numerous obsolescent punctures between pronotal foveae; 4, distinctive shape of apical portion of penis lobe ( Fig. 28 PL).

Description: Length 26.6–32 mm, pronotal width 7.3–9.1 mm, elytral width 8.4–10.3 mm. Colour of head and pronotum matte to glossy black, abdomen and elytra matte dark reddish-brown to black; coxae and legs dark reddish-brown.

Head: Very broad and flat. Vertex ( Fig. 9 ) with obsolescent wrinkles and sparsely punctured laterally, posterad vertexal groove; vertexal groove shallow, defined by obsolescent punctures laterally, smooth medially; large supraorbital puncture bearing 4–5 setae; 5–6 slightly impressed supraorbital grooves; frons with a large and shallow depression each side of midline, inistinctly grooved antero-laterally; frontoclypeal suture ( Fig. 9 ) narrow and well-defined, tentorial pits indistinct; anterior area of clypeus with 3 narrow and well-defined grooves, lateral grooves extended proximate the frontoclypeal suture; 1 setose puncture each side bearing 2 setae, 1 medial puncture within larger depression bearing 2 setae. Labrum lobate, anterior edge outwardly curved and moderately emarginated medially with 2 proximate central setae, 2 setae each side evenly spaced. Mentum lobes rounded ( Fig. 12F ), mentum process short and broad (especially base), moderately angled upward (30°), moderately indentate ( Fig. 12B ); mentum setae variably absent or present. Submentum sclerite constriction broad with 6–8 evenly spaced setae. Stipes with 2 basal setae. Gula pits ( Fig. 8 ) small, suture poorly defined, gula flat and smooth. Gena with rugose wrinkles forming an isodiametric pattern across entire area.

Prothorax: Prothoracic carina ( Fig. 11 ) broad the entire length, crenulations absent with 8–10 setae each side, carina extended beyond anterior angle; posterior lateral sinuation evidently carinate, parallel or slightly angled outward; pronotum flattened and slightly deflected laterally, overall shape cordate, fine transverse wrinkles across midline and laterally but a gap medially ( Fig. 28 ); midline well-defined, a large anterior medial triangular-shaped impression and posterior medial diamond-shaped impression present; pronotal foveae broad and shallow (may be obsolescent punctures and rugose wrinkles between foveae); anterior edge slightly inwardly curved, posterior edge straight ( Fig. 28 ). Prosternum ( Fig. 2 ) flat and smooth; proepisternum without microsculpture (a few obsolescent punctures may be present). Procoxal setae absent; protibia distally expanded and shovel-like ( Fig. 10B ).

Elytra: Broad and moderately deflected; humeral angle evenly convex ( Fig. 6B ); basal margin slightly curved and gently sloped to base, interval 1 extended to scutellum; lateral carina narrow entire length, broadened slightly in apical ¼, extended to humeral angle; humerus with 3 long setae proximate within angle, 1 double-spaced posterad ( Fig. 28 ); suture defined, but no more so than striae; striae with small, regularly spaced, asetose punctures slightly increased in size laterally, striae 1–5 entirely with obsolescent asetose punctures, striae 6–8 punctures more visible; intervals 1–4 flat, intervals 5–8 weakly convex, interval 9 moderately convex the entire length; interval microsculpture present as fine lines; 7 th strial setal pattern ( Fig. 1 ) with 4 setose punctures in anterior ½, 5 setose punctures in posterior ½, setose punctures large anteriorly, small posteriorly.

Ventral surface: Mesepisternum with several scattered punctures; metepisternum ( Fig. 2 ) without microsculpture; setose punctures present on mesocoxae (2) and metacoxae (1). All abdominal ventrites finely lineate; ventrites 3–5 with 1 setose puncture (may have 2 setose punctures on ventrite 3) each side of midline; ventrite 6 setae present: ♂ with 1 seta each side, apical edge bluntly curved, ♀ with 1 seta each side, apical edge bluntly curved; ventrites 2–5 foveate laterally. Anterior metaventrite process ( Fig. 2 ) a long triangle with a narrow and well-defined carina the entire length.

Male genitalia: Apical portion of penis lobe asymmetrically hooked and narrow (width) with a very distinct deflection to right of vertical axis (VV) ( Fig. 15A ); ventral edge of shaft curved downward to form the ventral process that is a very small, bluntly rounded point, apex steeply, though asymmetrically curved to form the long and narrow dorsal process ( Fig. 28 PL) with a rounded hook (in line with vertical axis ( Fig. 3 ), hook slightly recurved, long and sharply curved to dorsal part of shaft; penis lobe shaft slightly curved to right, only in apical portion (VV), shaft of penis equally narrow ( Fig. 28 PL), overall length slightly curved ventrally apically only (LV). 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 with projection; setal (scales) coverage of the apical plate extensive (76–100%); size of left setose flange large; size of right setose flange absent. Left paramere basal lobe rectangular with moderate dorsal hump; steeply sloped (60°) to very short and narrow arm; terminal lobe slightly broadened; ventral edge setal distribution as an apical tuft of very sparse (4–6) short setae, then a comb of long setae at armbasal lobe junction ( Fig. 28 LP); ventral edge straight. Right paramere a long and narrow rectangle to ½ length then narrows to terminal end, a double-row of long setae extending along apical ½ of ventral edge ( Fig. 28 RP); terminal ⅓ inwardly curved to penis lobe.

Female genitalia: Basal gonocoxite 1 ( Fig. 5 ) long and narrow but broadens apically and flattened, ventral surface smooth, internal dorso-lateral carina with 4 short setae, carina extended inward (dorsal view). Gonocoxite 2 ovate in shape, apical end slightly curved upward (dorsal view). Ramus long and narrow.

Comments: This species is described from 11 specimens collected by pitfall trapping in the Whakaroa S.R. during two different collecting events in 1993/4 and 1994/5.

Distribution: New Zealand, North Island, Gisborne, Waimata Valley, Whakaroa Scenic Reserve.

Holotype: NZAC male labelled. NEW ZEALAND GB Waimata V Whakaroa Scenic Res Saddle 30 Nov 1994 – / 9 Jan 1995 G. Hall Pit traps / HOLOTYPE Mecodema genesispotini n. sp. design. DS Seldon, TR Buckley 2018 [red label].

Paratypes: 1♀, NEW ZEALAND GB Whakaroa Scenic Reserve 22 Nov 1993 — 1 Jan 1994 / G. Hall pit trap ( NZAC) ; 2♂, 3♀ NEW ZEALAND GB Waimata V Whakaroa Scenic Res Saddle 30 Nov 1994 – / 9 Jan 1995 G. Hall Pit traps ( NZAC) ; 2♂, 2♀ NEW ZEALAND GB Whakaroa Scenic Res 22 Nov 1993 – 11 Jan 1994 / G. Hall Pit traps / PARATYPE ( NZAC) .

Etymology: This species is named in honour of the late Genesis Potini, who was a New Zealand speed chess champion from Gisborne. He was also the cofounder of the Gisborne Eastern Knights Chess Club, helping underprivileged Māori children by teaching them how to play chess.

Figures

FIGURE 1. Dorsal view of a Mecodema specimen showing taxonomic structures used in the species descriptions. H =head; P = pronotum; E = elytra; S = striae; I1 = interval 1; A = apex; 7S = 7 th strial setae; HSP = humerus setose puncture; HA = humeral angle; BM = basal margin; P = protibia.

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 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 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 28. Mecodema genesispotini 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.