Mecodema quoinense Broun, 1912

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 : 97-99

Mecodema quoinense Broun, 1912 .

Figure 49 .

Diagnosis: Distinguishable from all other North Island Mecodema species by: 1, striae 5–6 well-defined by asetose proximate punctures (interval very narrow), striae 7–8 comprise of a double row of punctures (no interval); 2, the rectangular shape of the apical portion of the penis lobe ( Fig. 49 PL).

Description: Length 23.7–24.7 mm, pronotal width 6.2–7 mm, elytral width 7.1–8.1 mm. Colour of entire body matte dark reddish-brown to matte black, coxae and tibiae dark reddish-brown, femur bright red or black.

Head: Narrow and convex ( Fig. 14D ). Vertex micropunctate, wrinkled grooves ( Fig. 49 ) and very fine wrinkles forming an isodiametric pattern laterally; vertexal groove micropunctate and wrinkled grooves the entire length, a broad shallow depression laterally; small supraorbital puncture bearing 3–4 setae; 3–4 shallow supraorbital grooves, extended on to frons anterior to eye; frons ( Fig. 9 ) medially convex with a large and shallow depression each side of midline, grooves laterally, plus wrinkled grooves and pitting in posterior region ( Fig. 49 ); frontoclypeal suture indistinct between very small tentorial pits; anterior clypeus with a central groove, extended forward laterally, rounded and anterior edge angled backward medially; clypeus area mesad setose punctures medially convex, 1 small setose puncture each side bearing 2 setae. Labrum rounded, anterior edge slightly emarginated with 2 proximate central setae, 2 setae each side evenly spaced. Mentum lobes rounded ( Fig. 12F ), median process long and broad, strongly angled upward (60°), distinctly indentate ( Fig. 12A ); mentum setae present. Submentum sclerite constriction narrow with 6 relatively evenly-spaced setae. Stipes with 2 basal setae. Gula pits ( Fig. 8 ) very small, suture indistinct, gula flat and smooth. Gena with rugose transverse wrinkles becoming corrugose toward prosternum (medially), fine wrinkles forming an isodiametric pattern laterally.

Prothorax: Prothoracic carina broad the entire length, slightly crenulated with 8–10 setae each side ( Fig. 49 ), extended beyond anterior angle; posterior sinuation defined as a continuation of carina, evidently carinate, inwardly angled; pronotum narrow and deflected, overall shape triangularly cordate with a raised carina behind anterior edge, very fine, transverse wrinkles across entire disc ( Fig. 49 ), isodiametric pattern across antero-lateral region; midline indistinct, anterior medial triangular impression and posterior medial diamond-shaped impression present; pronotal foveae ( Fig. 11 ) small and deep; anterior edge moderately inwardly curved, posterior edge straight. Prosternum flat with evenly-spaced, fine transverse lines, medial depression; proepisternum micropunctate. Procoxal setaeabsent; protibia distally expanded and shovel-like ( Fig. 10B ).

Elytra: Narrow and flat; humeral angle anteriorly convergent ( Fig. 6A ); basal margin moderately curved and bevelled to base, interval 1 extended to scutellum; lateral carina narrow the entire length, extended to humeral angle; humerus with 1 setose puncture; suture poorly defined; intervals slightly convex, convexity increased laterally, interval microsculpture present as fine transverse lines, interval 8 very broad, forming the side of the elytra to the carina; striae 1–4 with obsolescent asetose punctures (anterad and posterad), striae 5–6 well-defined by asetose proximate punctures (interval very narrow), striae 7–8 comprise of a double row of punctures (no interval); 7 th strial setal pattern with 0–3 setose punctures in anterior ½, 3–4 setose punctures in posterior ½ ( Fig. 49 ), setose punctures small.

Ventral surface: Mesepisternum with deep grooves (may be micropunctate); metepisternum with defined grooves proximate coxae; setose punctures present on mesocoxae (2) and metacoxae (2). All abdominal ventrites ( Fig. 2 ) finely lineate laterally; ventrites 1–3 micropunctate; ventrites 3–5 with 1 setose puncture each side of midline; ventrites 6 setae present: ♂ with 2 evenly spaced setae on bluntly rounded apical edge, ♀ specimen damaged; some ventrites foveate laterally (shallow). Anterior metaventrite process a short, sharply-pointed triangle with a broad and well-defined carina the entire length.

Male genitalia: Apical portion of penis lobe asymmetrically rounded without deflection to right (VV); apical portion shape almost squared, ventral process with slight point before apically flat curve upward to form the flatly curved dorsal process, that has a curved hollow in shaft to determine apex ( Fig. 49 PL); shaft of penis lobe narrow the entire length, ventral edge with distinct curve to right (VV); overall length of the penis lobe moderately curved ventrally, especially apical portion (LV) ( Fig. 16C ). Structures of the endophallus ( Fig. 4 ): lateral form of the apex of the central spicul rounded; dorsal form of the apex of the central spicule expanded; setal (scales) coverage of the apical plate extensive (76–100%); size of left setose flange small; size of right setose flange very large. Left paramere basal lobe articulated at right angle, rectangular without dorsal hump but steeply sloped (60°) to arm ( Fig. 49 LP); arm short and narrow; terminal lobe broad and short with apical tuft of medium-lengthed setae; setae extended along apical portion to arm-basal lobe junction; ventral edge straight ( Fig. 49 LP). Right paramere is a long and narrowly rectangular with a slight dorsal hump that forms a steep slope to arm, gradually narrowed to terminus, setae extended along apical ½ of ventral edge ( Fig. 49 RP).

Female genitalia: Basal gonocoxite 1 ( Fig. 5 ) short and broad, broadened toward gonocoxite 2, ventral surface with a few parallel, rugose wrinkles, internal dorso-lateral carina without setae; dorsally flattened carina in apical half. Gonocoxite 2 broadly triangular and apically reflexed. Ramus short and broad basally, narrowed apically, apical portion slightly curved inward.

Comments: Britton (1949) used the character ‘bright red femora’ to distinguish Mecodema quoinense from other Mecodema species in the area. However, this character is difficult to see in old, dry and pinned specimens, as well as being a relatively common occurrence in many other species. Britton should have utilised the male genitalia as the apical portion of the penis lobe is significantly different from any other Mecodema species.

Distribution: New Zealand, North Island, Wellington, Tararua Range, Mt Quoin and Mt Holdsworth.

Holotype: BMNH male labelled. Mecodema quoinense ♂ [hw] / Mount Quoin 3900 ft. [hw] / New Zeal. [red underline] Broun Coll. Brit. Mus. 1922-482. / 3167 [hw] / Type [round label with red border].

Material examined: 1♀ [card mounted], Mt. Holdsworth 3000’ 25.1.1907 [hw] G.V. HUDSON / Mecodema quoinense Br. [hw], E.B. Britton det. Comp. with Type. / AI.10446 ( MONZ) ; 1♀, ex J.J. Walker bequest 1939 / Ex Coll. Mus. Otago [hw] / Brit. Mus. 1948 129 / Mecodema quoinense Broun [hw] Compared with type. E.B.B. ( BMNH) .

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 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 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 49. Mecodema quoinense 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.