Mecodema crenaticolle Redtenbacher, 1868

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 : 36-39

Mecodema crenaticolle Redtenbacher, 1868 .

Figure 23 .

Mecodema rugicolle Broun, 1882 (nr Taranaki, TK), synonymised by Britton 1949.

Mecodema lineatum Broun, 1894 (Ligar’s Bush, AK), synonymised by Lewis 1902.

Diagnosis: Distinguishable from other North Island Mecodema species by having: 1, the pronotum carina strongly crenulated; 2, elytral striae 1–4 with large star-shaped asetose punctures in an irregular pattern, striae 5–7 with asetose punctures not star-shaped, but irregularly spaced; 3, an elytral setose puncture basad scutellum.

Description: Length 21–27.9 mm, pronotal width 5.8–7.3 mm, elytral width 6.7–8.6 mm. Colour of entire body reddish-brown to black.

Head: Broad and convex ( Fig. 14B ). Vertex with coarse transverse wrinkles laterally, becoming an isodiametric pattern toward pronotum; vertexal groove ( Fig. 8 ) defined by punctures and coarse wrinkles the entire length; small supraorbital puncture bearing 3–4 setae, greater than 3 well-defined supraorbital grooves anterad eyes ( Fig. 23 ), extended onto frontoclypeal area; frons with a few scattered punctures between supraorbital punctures, cuticle raised medially, a shallow depression each side of midline (anteriorly); frontoclypeal suture absent, tentorial pits indistinct within grooves; anterior area of clypeus ( Fig. 9 ) with shallow grooves, 1 small setose puncture on each side bearing 2 setae (a medial puncture bearing 1 seta may be present). Labrum rounded laterally, anterior edge outwardly curved with 2 proximate central setae, 2 setae each side evenly spaced. Mentum lobes squared ( Fig. 12G ), median process broad and short, apex slightly angled upward (15°), distinctly indentate ( Fig. 12A ); mentum setae present. Submentum sclerite constriction ( Fig. 8 ) narrow, broadened laterally with 6 regularly spaced setae. Stipes with 2 basal setae. Gula pits small, suture well-defined, gula flat with rugose transverse lines. Gena convex and entirely covered with transverse tight wrinkles that form an isodiametric pattern laterally.

Prothorax: Prothoracic carina ( Fig. 11 ) very narrow the entire length, distinctly crenulated with 6–10 relatively evenly spaced setae along each side ( Fig. 23 ), extended to anterior angle; posterior lateral sinuation evidently carinate, parallel or slightly angled outward (very distinctive as it is formed by foveael groove); pronotum laterally deflected, disc with deep transverse grooves laterally (less impressed proximate the midline), overall shape cordate, medial impressions absent; pronotal foveae ( Fig. 11 ) broad and deep, partially formed by convexity of pronotal lateral margin; anterior edge distinctly inwardly curved, convexity forming ridge that is grooved perpendicular to anterior edge, posterior edge distinctly emarginated medially. Prosternum ( Fig. 2 ) flat with a shallow depression each side of midline; proepisternum moderately wrinkled and pitted. Procoxal setae absent; protibia distally expanded and shovel-like ( Fig. 10B ).

Elytra: Narrow and deflected laterally, posterior end of elytra steep to apex; humeral angle anteriorly convergent ( Fig. 6A ); basal margin angled perpendicular to humeral angle and bevelled to base; lateral carina ( Fig. 1 ) very narrow from apex to humerus (may be broadened in posterior ⅓), distinctly crenulated in anterior ⅓ to slightly crenulated in posterior ⅓, extended to humeral angle, carina with a distinctive curve inwardly posterad humerus; humerus with 3 deep setose punctures; suture well-defined; stria 1 anterior area with small, asetose punctures in a row, medial punctures increased in size, apical punctures star-shaped; stria 2 defined by evenly distributed star-shaped punctures, striae 3–5 obliterated by large star-shaped punctures in confused distribution, striae 6–8 more discernible as irregularly sized and spaced, asetose punctures ( Fig. 23 ); intervals 1 and 2 visible, extended to scutellum but not defined by striae, interval 3 convex in posterior ⅓, intervals 4–8 undefined; 7 th strial setal pattern with 4 setose punctures in anterior ½, 4–6 setose punctures in posterior ½, setose punctures large; a single seta each side near base end of stria 2 ( Fig. 23 ).

Ventral surface: Mesepisternum with corrugose wrinkles; metepisternum moderately punctured, punctures continue to lateral area of ventrites 1 and 2; setose punctures present on mesocoxae (2) and metacoxae (3). Abdominal ventrites 1 and 2 finely lineate and finely micropunctate extended to coxa; ventrites 3–5 with 1 deep, setose puncture each side of midline, ventrites foveate laterally; ventrite 6 setae present: ♂ with a pair of setae each side, posterior edge straight; ♀ with 1 pair each side, 1 proximate apex, posterior edge a rounded point. Anterior metaventrite process a short triangle with a very well-defined and broad carina the entire length.

Male genitalia: Apical portion of penis lobe asymmetrically hooked with a moderate deflection to right of vertical axis (VV) ( Fig. 15B ); dorsal process ( Fig. 3 ) a narrow and bluntly rounded hook that is slightly pushed forward of perpendicular, apex with an asymmetrical curve downward to form the ventral process ( Fig. 3 ), that is a very bluntly rounded point, half the size of the dorsal process ( Fig. 23 PL); penis lobe shaft equally narrow width the entire length, apical portion straight (VV); 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 long and narrow; relative setal (scales) coverage of the apical plate moderate (26–75%); size of left setose flange large; size of right setose flange very large (long). Left paramere basal lobe rectangular with a very pronounced dorso-anterior hump (70–80°) angle sloping to arm; arm very narrow and continued to terminal lobe (not distinguishable from arm), apical tuft without setae, sparsely scattered setae along apical ⅓ of ventral edge ( Fig. 23 LP); ventral edge of basal lobe straight. Right paramere triangular with a pronounced anterio-dorsal hump ( Fig. 23 RP), arm longer than basal lobe, a double row of long setae reducing in number along apical ¾ of ventral edge.

Female genitalia: Basal gonocoxite 1 long and broad with ventral surface smooth, internal dorso-lateral carina with 3 short setae. Gonocoxite 2 ( Fig. 5 ) a rounded triangle, paddle-like, ventral surface with numerous sensilla. Ramus long and narrow.

Comments: There is some variation inpronotal and elytral characters among North Island populations, but the umbilitical setose punctures of humerus are stable. Mecodema crenaticolle is widespread from the Wellington Region to the Hunua Range, Auckland, with the western populations of Whanganui and Mt Taranaki showing the most morphological variation. Mecodema crenaticolle can be distinguished from its sister species, M. crenicolle (South Island) by having large, star-shaped, asetose punctures medially, and the ventral surfaces are defined by rugose wrinkles and punctures.

Distribution: New Zealand, North Island, Auckland, Coromandel, Bay of Plenty, Waikato, Taupo, Taranaki, Rangitikei, Wanganui, Wellington.

Holotype: (not viewed). Type in the Museum of Natural History, Vienna.

Paratypes ( Mecodema crenaticolle ): BMNH, male labelled. 2594. ♂ [hw] / Type [round label with red border] / New Zealand [red underline] Broun Coll. Brit Mus. 1922—482 / Ligar’s Bush. Papakura [hw] / Mecodema lineatum [hw] / Mecodema crenaticolle Redt. [hw] Compared to type E.B.B.; BMNH. Type [round label with red border] / 1322 / New Zealand [red underline] Broun Coll. Brit Mus. 1922—482 / Taranaki / card-mounted male genitalia / Mecodema rugicolle [hw].

Material examined: 1 ♀, NZ WO 7 km W Karamu 14.XI.1992 A. Larochelle. M-C Larivière / Totara and tree fern for., under pieces of wood ( NZAC) ; 1, NEW ZEALAND. TK. Mt Taranaki, Lower Lake Dive Tk , 28 Mar 2106, D.S. Seldon, F.R. Schnitzler, M. Dickison. / Low broadleaf canopy, log rolling, S39°19’17.2 E174°05’50.1 984 m ( WMNZ) ; 2, NEW ZEALAND. TK. Mt Taranaki, Sir Eds Seat Tk , 28 Mar 2106, D.S. Seldon, F.R. Schnitzler, M. Dickison. / Very low broadleaf canopy, under logs, S39°19’16.4 E174°05’44.8, 1013 m ( WMNZ) .

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 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 23. Mecodema crenaticolle 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.