Mecodema jacinda, 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 : 57-60

Mecodema jacinda sp. n.

Figure 32 .

Diagnosis: Differing from all other North Island Mecodema species by: 1, vertex smooth, vertexal groove defined by a few obsolescent punctures; 2, the pronotal carina broad the entire length with 8–12 setae each side; 3, interval 7 strongly convex in apical ⅓ (very distinctive); 4, the shape of the apical portion of the penis lobe ( Fig. 32 PL).

Description: Length 29–36 mm, pronotal width 7.9–10.2 mm, elytral width 9.1–11.6 mm. Colour of entire body matte to glossy black (especially pronotum).

Head: Broad and flat ( Fig. 14A ). Vertex with very fine (almost indistinct) lines forming an isodiametric pattern, especially laterally; vertexal groove broad and slightly impressed, defined by scattered obsolescent punctures ( Fig. 32 ); small supraorbital puncture bearing 3–5 setae; 3–4 slightly impressed supraorbital grooves; frons ( Fig. 9 ) with a large and shallow depression each side of midline, indistinctly grooved antero-laterally; frontoclypeal suture well-defined, medially convex, tentorial pits small; anterior area of clypeus with deep grooves each side and medially, 1 large setose puncture each side bearing 2 setae, medial setose puncture large bearing 1 seta. Labrum rectangular, anterior edge straight, very slightly emarginated with 2 proximate central setae, 2 setae each side evenly spaced. Mentum lobes rounded ( Fig. 12F ), median process very short and broad, moderately angled upward (30°), moderately indentate ( Fig. 12B ); mentum setae absent. Submentum sclerite ( Fig. 8 ) constriction broad with 6–8 setae evenly spaced. Stipes with 2 basal setae. Gula pits large, suture well-defined, gula flat and smooth. Gena with fine transverse wrinkles across entire area.

Prothorax: Prothoracic carina broad the entire length, crenulations absent with 8–12 setae each side ( Fig. 32 ), extended beyond anterior angle; posterior lateral sinuation indistinctly carinate, parallel; pronotum broad and laterally deflected, overall shape cordate ( Fig. 32 ); midline slightly impressed, anterior medial triangular impression and posterior medial diamond-shaped impression present, disc with very fine transverse wrinkles ( Fig. 32 ) and a small shallow depression each side (midway); pronotal foveae broad and deep; anterior edge slightly inwardly curved, posterior edge straight. Prosternum ( Fig. 2 ) flat with a series of transverse broad and shallow grooves; proepisternum without microsculpture. Procoxal setae absent; protibia distally expanded and shovel-like ( Fig. 10B ).

Elytra: Broad and moderately deflected laterally; humeral angle evenly convex ( Fig. 6B ); basal margin sharply curved (truncated by intervals 1 and 2 extending to scutellum) and bevelled to base; lateral margin narrow medially but broadened in anterior ⅓ and posterior ⅓, extended beyond humeral angle; humerus with 3–4 setose punctures along angle ( Fig. 32 ); suture slightly impressed; striae 1–4 impressed as lines (punctures obsolescent); striae 5–8 with punctures becoming more visible, all small and regularly spaced; intervals 1–4 weakly convex, intervals 5–9 moderately convex, interval 7 strongly convex in apical ⅓ (very distinctive); interval microsculpture present as fine transverse lines; 7 th strial setal pattern with 2–3 setose punctures in anterior ½, 5–6 setose punctures in posterior ½, setose punctures large.

Ventral surface: Mesepisternum sparsely punctured; mesosternum with tranverse grooves, metepisternum ( Fig. 2 ) without microsculpture; setose punctures present on mesecoxa (2) can have multiple setae, and metacoxa (2). All abdominal ventrites ( Fig. 2 ) finely lineate; ventrites 3–5 with 1 setose puncture each side of midline; ventrite 6 setae present: ♂ with 1 seta each side at junction of straight apical edge and curve anterad, ♀ with 2 setae each side between straight apical edge; lateral foveae absent. Anterior metaventrite process a short triangle with broad and moderately defined carina the entire length.

Male genitalia: Apical portion of penis lobe asymmetrically hooked and width narrow (vertically), ventral process formed by a long curve downward from shaft to form a bluntly rounded point, pushed forward of vertical axis (LV) ( Fig. 3 ), apex with a flattened curve upward to form the dorsal process, that is a very bluntly rounded, short and squat hook with a gentle curve to shaft ( Fig. 32 PL); shaft of penis lobe with a slight deflection to right of vertical axis VV ( Fig. 15C ); shaft moderately curved to right the entire lenght (VV), penis lobe shaft narrow for apical ⅓ then gradually broadened to base; 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 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 small; size of right setose flange absent. Left paramere basal lobe narrow and rectangular with a moderate dorsal hump, that forms a moderate (45°) slope to arm; arm long and narrow; terminal lobe broader than arm with a apical tuft of sparse short setae ( Fig. 32 LP); comb of long setae from mid-arm to junction of basal lobe; setae extended along apical ⅓ of ventral edge; ventral edge straight. Right paramere a very narrow triangle that narrows towards terminal end, a double row of long setae extended along apical ½ of ventral edge ( Fig. 32 RP).

Female genitalia: Basal gonocoxite 1 short and broad apically, ventral surface covered in deep grooves, internal dorso-lateral carina with 3 setae. Gonocoxite 2 with a broadly rounded apex, shortened with a broad base. Ramus ( Fig. 5 ) long and relatively broad.

Comments: The largest of the three Mecodema species found at Maungatautari E.R., this species is relatively abundantly collected in pitfall traps and by log rolling.

Distribution: New Zealand, North Island, Waikato, Maungatautari Ecological Reserve.

Holotype: NZAC male labelled. NEW ZEALAND WO, Maungatautari E.R., PTs, Jan–Feb 2009, C. Watts, Landcare / HOLOTYPE Mecodema jacinda n. sp. design. DS Seldon, TR Buckley 2018 [red label].

Paratypes: 1, NEW ZEALAND WO, Maungatautari E.R., PTs, 20 Nov–17 Dec 2008, C. Watts, Landcare ( LUNZ); 4 , NEW ZEALAND WO, Maungatautari E.R., PTs, 17 Dec 2008 – 18 Jan 2009, C. Watts, Landcare ( AMNZ); 3, 1♀ , NEW ZEALAND WO, Maungatautari E.R., PTs, 18 Jan–17 Feb 2009, C. Watts, Landcare ( NZAC); 1♂, 1♀ , NEW ZEALAND WO, Maungatautari E.R., PTs, 18 Jan–17 Feb 2009, C. Watts, Landcare ( MONZ) .

Etymology: Mecodema jacinda is named to honour Jacinda Ardern, leader of the Labour Party.

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 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 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 32. Mecodema jacinda 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.