Mecodema moniliferum Bates, 1867

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 : 74-76

Mecodema moniliferum Bates, 1867 , comb. n.

Figure 39 .

Metaglymma monilifer Bates, 1867 (Canterbury) .

Metaglymma rugipenne Broun, 1893a (Ashburton, MC), synonymised by Britton 1949.

Metaglymma minor Broun, 1905 (north Canterbury), synonymised by Britton 1949.

Diagnosis: Distinguished from other Mecodema species by having: 1, ventrites 4–5 bearing numerous setose punctures; 2, elytral striae defined anteriorly and laterally by large, irregularly spaced asetose punctures ( Fig. 39 ); 3, shape of basal lobe and setal distribution along ventral edge of left paramere ( Fig. 39 LP).

Description: Length 14.6–19.5 mm, pronotal width 4.2–6.2 mm, elytral width 5.1–7.1 mm. Colour of entire body matte reddish-brown to matte black.

Head: Narrow and flat ( Fig. 14C ). Vertex ( Fig. 9 ) smooth; vertexal groove narrow laterally, indistinct medially; large supraorbital puncture bearing 4–5 setae; 1 shallow supraorbital groove; frons with a small rounded depression each side of midline; frontoclypeal suture a distinctly narrow, straight groove between small tentorial pits; anterior area of clypeus smooth, 1 setose puncture each side bearing 1 seta ( Fig. 39 ). Labrum rounded, anterior edge outwardly curved with 2 proximate central setae, 2 setae each side evenly spaced. Mentum lobes squared ( Fig. 12G ), mentum process long and broad, slightly angled upward (15°), strongly indentate ( Fig. 12A ); mentum setae present. Submentum sclerite constriction narrow with 6 setae, large gap medially, evenly distributed laterally. Stipes with 2 basal setae. Gula pits large, suture poorly defined, gula flat with transverse lines. Gena ( Fig. 2 ) with fine wrinkles across entire area.

Prothorax: Prothoracic carina broad the entire length, moderately crenulated with 5–8 setae each side ( Fig. 39 ), extended to anterior angle; posterior lateral sinuation indistinctly carinate, slightly angled inward; pronotum broad and moderately deflected laterally, overall shape rounded; midline indistinctly impressed, posterior medial diamond-shaped impression only, disc with very fine wrinkles laterally ( Fig. 39 ); pronotal foveae broad and shallow; anterior edge slightly inwardly curved, posterior edge curved inwardly medially. Prosternum flat with very fine lines; proepisternum without microsculpture. Procoxal setae ( Fig. 2 ) absent; protibia distally expanded and shovel-like ( Fig. 10B ).

Elytra: Broad and moderately deflected, length truncated and steeply sloped to apex; humeral angle evenly convex ( Fig. 6B ); basal margin distinctly curved and bevelled to base, interval 1 extended to margin; lateral carina narrow the entire length, extended to humeral angle; humerus with 4–6 setose punctures within angle ( Fig. 39 ); suture impressed but no more so than striae; striae with small, regularly spaced, asetose punctures, striae 1–4 with obsolescent punctures, increasingly defined laterally ( Fig. 39 ); intervals 1–6 weakly convex, intervals 7–9 moderately convex; interval microsculpture present as transverse lines; 7 th strial setal pattern with 2–3 setose punctures in anterior ½, 5–6 setose punctures in posterior ½, setose punctures small.

Ventral surface: Mesepisternum ( Fig. 2 ) with a few rugose wrinkles; metepisternum without microsculpture; setose punctures present on mesocoxae (1) and metacoxae (2). All abdominal ventrites finely lineate laterally (sparse); ventrite 3 with 1–2 setose punctures each side of midline, ventrite 4 with 3–4 setose punctures each side of midline, ventrite 5 with 6–8 setose punctures each side of midline; ventrite 6 setae present: ♂ with 2 setose punctures at junction of straight apical edge and curve anterad, ♀ with 2 setose punctures, distantly spaced at junction of bluntly rounded apical edge and curve anterad; ventrites foveate laterally. Anterior metaventrite process ( Fig. 2 ) a long narrow triangle without a carina.

Male genitalia: Apical portion of penis lobe asymmetrically rounded with a distinct deflection to right of vertical axis (VV) ( Fig. 15A ), apex curve flat and slightly forward of vertical axis ( Fig. 39 PL); shaft of penis lobe broad and short with curve of ventral edge to left (VV); overall length of penis lobe without curve ventrally (straight). Structures of the endophallus ( Fig. 4 ): lateral form of the apex of the central spicule rounded; dorsal form of the apex of the central spicule short and narrow; setal (scales) coverage of the apical plate sparse (1–25%); size of left setose flange small; size of right setose flange large. Left paramere basal lobe ovate, dorsal hump absent with short slope to arm; arm long and narrow; terminal lobe not defined, apical tuft of long setae ( Fig. 39 LP); very short setae along arm ventral edge, long setae along basal lobe ventral edge; ventral edge slightly curved, setae along entire length. Right paramere long and narrowly rectangular, slightly narrowed to apex, setae extended along apical ¾ of ventral edge ( Fig. 39 RP).

Female genitalia: Basal gonocoxite 1 short and broad, ventral surface with a few rugose wrinkles; internal dorso-lateral carina with 2 setae. Gonocoxite 2 short and broad, ovate in shape; 1 short seta at base near junction with gonocoxite 1 (ventral surface). Ramus ( Fig. 5 ) long and broad.

Comments: Although Mecodema moniliferum is only found in the braided river systems of the South Island, analyses show that it nested within the monophyletic curvidens species group.

Distribution: New Zealand, South Island, Kaikoura (KA), north to south Canterbury (MC, NC, SC).

Holotype: not viewed. Type in the R. Oberthür Collection at Rennes, Muséum of National d’Histoire Naturelle , France. Type locality near Christchurch; collected by Mr Fereday ( Britton, 1949).

Material examined: 1♀, Moyunau I. 1–5.xii.67 / Pit traps A. Whittaker / Metaglymma monilifer Bates Det. J.I. Townsend 18.I.68 [hw] ( NZAC) ; 2, Waikuku Beach, Rangiora, 2 Dec 1941, D. Spiller [hw] ( NZAC) ; 1♂, 1♀ [card mounted], Mt Algidus, 2000’, 2– 13.12.59, J.I.Townsend ( NZAC) .

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 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 39. Mecodema moniliferum 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.