Mecodema florae Britton, 1949

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 : 46-48

Mecodema florae Britton, 1949 .

Figure 27 .

Diagnosis: Distinguishable from other North Island Mecodema species by having: 1, vertexal groove shallow, defined entirely by obsolescent punctures; 2, overall shape of pronotum ovate, prothoracic carina setae to sinuation; 3, proepisternum with numerous punctures in short grooves (deep wrinkles); 4, distinctive shape of apical portion of the penis lobe ( Fig. 27 PL).

Description: Length 17.5–19.5 mm, pronotal width 3.9–5.1 mm, elytral width 4.7–6.1 mm. Colour of body dorsally matte black, may be reddish-brown, ventrally dark reddish-brown.

Head: Narrow and flat ( Fig. 14C ). Vertex with wrinkles laterally and posteriorly, obsolescent punctures present posterad vertexal groove; vertexal groove shallow, well-defined entirely by obsolescent punctures ( Fig. 27 ); small supraorbital puncture bearing 4–5 setae; 2–3 shallow supraorbital grooves; frons with a shallow groove each side of midline, obsolescent punctures anterad vertexal groove, otherwise smooth; frontoclypeal suture narrow and well-defined the entire length, tentorial pits ( Fig. 9 ) indistinct; anterior area of clypeus with poorly defined but broad grooves, 1 setose puncture each side bearing 2 setae. Labrum rectangular, anterior edge straight with 2 proximate central setae, 2 setae each side evenly spaced. Mentum lobes squared ( Fig. 12G ), mentum process short and broad (especially at the base), slightly angled upward (15°), moderately indentate ( Fig. 12B ); mentum setae present. Submentum sclerite constriction narrow with 6 evenly spaced setae. Stipes with 2 basal setae. Gula pits ( Fig. 8 ) small, suture well-defined, gula flat with fine transverse lines variably present or absent. Gena with rugose lines forming an isodiametric pattern across entire area.

Prothorax: Prothoracic carina narrow the entire length, moderately crenulated with 6–9 setae along each side of carina almost to sinuation ( Fig. 27 ), extended beyond anterior angle; posterior lateral sinuation indistinctly carinate, inwardly angled; pronotum narrow and moderately deflected, almost ovate in shape; midline slightly impressed, anterior medial triangular impression and posterior medial diamond-shaped impression present, fine transverse wrinkles across entire disc, obsolescent punctures may be present proximate the anterior edge ( Fig. 27 ); pronotal foveae narrow and shallow (may be indistinct); anterior edge inwardly curved, posterior edge straight. Prosternum ( Fig. 2 ) weakly convex with fine transverse lines; proepisternum with numerous punctures in short grooves (deep wrinkles). Procoxal setae absent; protibia distally expanded and shovel-like ( Fig. 10B ).

Elytra: Narrow and deflected laterally, ovate in shape ( Fig. 27 ); humeral angle anteriorly convergent ( Fig. 6A ); basal margin distinctly perpendicular to humeral angle and gently sloped to base, interval 1 extended to scutellum; lateral carina narrow the entire length (broadened slightly in apical ¼), extended to humeral angle; humerus with 2 long setae proximate within angle, 1 double-spaced posterad; suture well-defined, often more so than striae; striae with irregularly spaced (may be joined), obsolescent asetose punctures, star-like lines radiate from punctures in apical area ( Fig. 27 ); intervals weakly convex, not well-defined; interval microsculpture present as fine lines; 7 th strial setal pattern with 3–4 setose punctures in anterior ½, 6–7 setose punctures in posterior ½, setose punctures small.

Ventral surface: Mesepisternum ( Fig. 2 ) with numerous punctures in short wrinkles, spilling onto lateral mesosternum; metepisternum without microsculpture; setose punctures present on mesocoxae (2) and metacoxae (2–3). Abdominal ventrites 1 and 2 with sparse obsolescent punctures; ventrites 2–5 with 1 setose puncture (some specimens may have 2 setose punctures) each side of midline; ventrite 6 setae present ( Fig. 2 ): ♂ with 1 seta each side, apical edge bluntly curved, ♀ with 1 pair of setae each side, apical edge a rounded point; ventrites 3–5 foveate. Anterior metaventrite process a short triangle with a very broad and well-defined 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 ); apical ventral process formed by a very shallow and broadly rounded curve, that then curves dorsad symmetrically forming dorsal process, that is a flattened but broad and rounded hook with a small point above the shaft ( Fig. 27 PL), ventral edge of penis lobe slightly curved to right (VV), shaft of penis lobe narrow the entire length but broadened forming apical portion ( Fig. 27 PL); 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 long and narrow; setal (scales) coverage of the apical plate moderate (26–75%); size of left setose flange small; size of right setose flange small (endophallus structures the same in all populations). Left paramere basal lobe a short rectangle, extended from articulation at right angle, dorsal hump absent, very steeply sloped (60°) to arm; arm very narrow and short, steeply sloped to indistinct terminal lobe; apical tuft with a few very sparse setae ( Fig. 27 LP); setal fringe along apical portion of ventral edge absent; ventral edge of basal lobe straight. Right paramere narrow and rectangular ( Fig. 27 RP), gradually narrowed to terminus, apical ⅓ curved inwardly across penis lobe; medium length setae extended along apical ¾ of ventral edge.

Female genitalia: Basal gonocoxite 1 short and broad, ventral surface smooth, especially apically, flattened, internal dorso-lateral carina with 1 seta placed medially of short edge. Gonocoxite 2 short and bluntly rounded triangular. Ramus ( Fig. 5 ) long and narrow, broadened slightly apically.

Comments: Mecodema florae is a North Island species that is also found in the northwest Nelson region (South Is.). Even though it is widely distributed geographically, it is mainly restricted to higher altitudes in the North Island, e.g. in Boundary Stream this species was only collected above 700 m.

Distribution: New Zealand, North Island, Taranaki, Gisborne, Hawke’s Bay, Rangitikei, Taupo; South Island: Buller, Northwest Nelson.

Holotype: not viewed, BMNH ( Britton 1949).

Material examined: 1♀, NEW ZEALAND HB Boundary Stream Mainland Island , Bell Rock PTs 1.4.3, 15 Dec 2008 – 15 Jan 2009, DoC ; 1♂, Beech forest Nth Moawhango Taihape 5.4.85 J.I. Townsend [hw] / J.I. Townsend Collection / NZAC04009692 ; 1, NEW ZEALAND TK Pouakai Ra. Ahu Kawakawa Track 1010m 12 Jan 1978 J.C. Watt [hw] / ex dead Libocedrus bidwillii [hw] ( NZAC) ; 1♂ (abdomen only), NEW ZEALAND HB Kaweka FP, Makahu Saddle , Ngahere Loop tk 1000m 22.II and 1.III 1996 Larivière. Larochelle / Mtn beech for.: wet, rich soil. Under and in rotten embedded logs / Death feigning ( NZAC); 1, NEW ZEALAND TK Pouakai Ra 1–13 Jan 1978 J.C. Watt Pit trap / NZAC04004801 .

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 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 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.