Mecodema longicolle Broun, 1923

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 : 67-69

Mecodema longicolle Broun, 1923 .

Figure 36 .

Mecodema subaeneum Broun, 1923 (Martinborough, WA), synonymised by Britton, 1949.

Diagnosis: Distinguished from other North Island Mecodema species by having: 1, stipes with 3 basal setae seta; 2, prothoracic carina narrow the entire length, moderately crenulated with 7–9 setae each side; 3, distinctive shape of apical portion of the penis lobe ( Fig. 36 PL).

Description: Length 15.5–20 mm, pronotal width 3.9–5 mm, elytral width 4.7–6 mm. Colour of entire body dark reddish-brown to glossy black, coxae reddish-brown, legs black.

Head: Narrow and convex ( Fig. 14D ). Vertex with very fine wrinkles (almost indistinct); vertexal groove slightly impressed, defined by punctures and short rugose wrinkles the entire length ( Fig. 36 ); large supraorbital puncture bearing 3–4 setae; 3–4 shallow and short supraorbital grooves; frons ( Fig. 9 ) with indistinct grooves, a large and shallow depression each side of midline anterad; frontoclypeal suture well-defined, tentorial pits small; clypeus convex medially, anterior with 3 narrow and indistinct grooves, 1 setose puncture on each side bearing 2 setae. Labrum rectangular, anterior edge slightly emarginated with 2 proximate central setae, 2 each side evenly spaced. Mentum lobes squared ( Fig. 12G ), median process broad and very short, slightly angled upward (15°) apically, strongly indentate ( Fig. 12A ); mentum setae present. Submentum sclerite constriction narrow with 6–8 evenly spaced setae. Stipes with 3 basal setae. Gula pits ( Fig. 8 ) relatively large, gula suture defined entire length, gula flat and smooth. Gena with wrinkled lines forming an isodiametric pattern across entire area.

Prothorax: Prothoracic carina narrow the entire length, moderately crenulated with 7–9 setae each side ( Fig. 36 ), extended to anterior angle; posterior lateral sinuation indistinctly carinate, angled inward; pronotum narrow and greatly deflected, overall shape ovate, disc with transverse wrinkles, anterior and posterior edges with short rugose lines perpendicular to edge ( Fig. 36 ); midline well-defined, anterior medial triangular-shaped impression and posterior medial diamond-shaped impression present; pronotal foveae shallow and narrow (may be indistinct); anterior and posterior edges inwardly curved ( Fig. 36 ). Prosternum flat with fine transverse lines, a small circular depression each side; proepisternum with numerous obsolescent punctures. Procoxal setae absent; protibia distally expanded and shovel-like ( Fig. 10B ).

Elytra: Narrow and greatly deflected, apex with steep slope; humeral angle anteriorly convergent ( Fig. 6A ); basal margin moderately curved and bevelled to base, interval 1 extended to margin; lateral carina very narrow the entire length, extended to humeral angle; humerus with 1–2 proximate setose punctures ( Fig. 36 ); suture welldefined; striae 1–4 defined by long, narrow asetose punctures, irregularly spaced, striae 5–8 well-defined by larger asetose punctures; intervals 1–4 indistinct but anterior area flattened, elytra greatly deflected, interval 5 weakly convex, intervals 6–8 indistinct, interval microsculpture present as very fine lines emanating from punctures; 7 th strial setal ( Fig. 1 ) pattern with 3 setose punctures in anterior ½ (1 st setae is on junction of basal margin and 7 th stria), 5–6 setose punctures in posterior ½, setose punctures large.

Ventral surface: Mesepisternum ( Fig. 2 ) with numerous obsolescent punctures; metepisternum without microsculpture; setose punctures present on mesocoxa (2) and metacoxa (3). Abdominal ventrites 1 and 2 finely lineate with sparse obsolescent punctures; ventrites 3–5 lineate laterally, 1 setose puncture each side of midline; ventrite 6 ( Fig. 2 ) setae present: ♂ with 2 closely-spaced, short setae each side, apical edge squared between punctures, ♀ with 2 widely spaced, long setae on each side of midline, apical edge a obtusely rounded; ventrites foveate laterally (may be indistinct). Anterior metaventrite process a short triangle with a well-defined carina, apically broad and narrowed posterad.

Male genitalia: Apical portion of penis lobe asymmetrically hooked ( Fig. 36 PL) with a moderate deflection to right of vertical axis (VV) ( Fig. 15B ); apex of penis lobe shaft broadened ventrally curved symmetrically upward to form the dorsal process, a narrowly rounded and recurved hook ( Fig. 36 PL), evenly curved to shaft dorsad; ventral edge of penis lobe shaft straight (VV); penis lobe shaft very narrow, overall length slightly curved ventrally ( Fig. 36 PL), almost straight (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 long and narrow; setal (scales) coverage of the apical plate extensive (76–100%); size of left setose flange small; size of right setose flange large. Left paramere basal lobe narrow and rectangular without dorsal hump, short curved slope to arm; arm short and narrow ( Fig. 36 LP); terminal lobe indistinct from arm with apical tuft of short, very sparse setae, extended along arm only; ventral edge straight ( Fig. 36 LP). Right paramere a narrowly rectangular for ½ length then gradually narrowed to terminal lobe, double row of setae extended along apical ¾ of ventral edge ( Fig. 36 RP), apical ⅓ inwardly curved toward penis lobe.

Female genitalia: Basal gonocoxite 1 long and narrow the entire length, internal dorso-lateral carina without setae, ventral surface smooth. Gonocoxite 2 ( Fig. 5 ) a rounded diamond-shaped, terminal dorsal carina with small undulations and reflexed. Ramus long and relatively broad.

Comments: Externally M. longicolle and M. florae look very similar, and both species overlap geographically. However, the male internal aedeagal character are completely different, especially the apical portion (see Figs 27 PL and 36PL).

Distribution: New Zealand, North Island, Mt Taranaki, Mt Hikurangi, Ruahine Range, Rangitikei.

Holotype: BMNH male labelled. Type [round label with red border] / New Zeal. [red underline] Broun Coll. Brit. Mus. 1922—482. / 4259 [hw] / Mt Egmont 6.4.1918. [hw] / Hudson, 6 G7. n.sp [hw] / Mecodema longicolle [hw]. Exposed aedeagus apex damaged.

Paratype ( Mecodema subaeanum ): BMNH male labelled. Type [round label with red outer circle] / New Zeal. [red underlined] Broun Coll. Brit. Mus. 1922—482. / 4262 ♂ [hw] / Martinborough 20.1.1919. [hw] / Mecodema subaeanum ♂ [hw] .

Material examined: 1♂, NEW ZEALAND 511 [hw] G.V. Hudson / Mecodema sp [hw] Det. G.E. Bryant / Mecodema subaeanum Br [hw] E.B. Britton det. 1936 [hw] / Genitalia card mounted (BMNH); 1♀, NEW ZEALAND RI Ruahine SFP, Rangitane Rd end, Kawhatau Base, 25.II–1.III.1994, Larivière. Larochelle / 800m Very wet, well drained horopito-Melicytus-tree fern for.; rich litter. Pittraps.

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 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 27. Mecodema florae 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.

FIGURE 36. Mecodema longicolle 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.