Mecodema tibiale Castelnau, 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 : 123-126

Mecodema tibiale Castelnau, 1867 , comb. n.

Figure 60 .

Maoria tibialis Castelnau, 1867 (Puerua (Molyneux) River, SL).

Metaglymma tibiale Castelnau, 1868 , redescribed.

Metaglymma rufipes Broun, 1886 (nr. Outram, DN), synonymised by Britton 1949.

Metaglymma asperum Broun, 1893a (Taiera Beach, DN), synonymised by Britton 1949.

Metaglymma junctum Broun, 1893a (Strath-Taiera, CO), synonymised by Britton 1949.

Metaglymma calcaratum Broun, 1903 (Maniototo, CO), synonymised by Britton 1949.

Diagnosis: Differs from other Mecodema species by having: 1, ventrites 4 and 5 with multiple setose punctures each side of midline; 2, apical area of elytra with numerous setose punctures; 3, shape of basal lobe and setal distribution along ventral edge of left paramere ( Fig. 60 LP).

Description: Length 14.6–18.4 mm, pronotal width 4.3–5.5 mm, elytral width 5–6.4 mm. Colour of body dorsally matte reddish-brown to glossy black, ventrally matte to glossy reddish-brown on ventrites and legs.

Head: Broad and convex ( Fig. 14B ). Vertex smooth ( Fig. 60 ); vertexal groove slightly impressed laterally, absent medially; large supraorbital puncture bearing 3 setae; supraorbital grooves absent; frons with a small and shallow depression each side of midline (anteriorly); frontoclypeal suture ( Fig. 9 ) a well-defined groove, tentorial pits large and well-defined; anterior area of clypeus without microsculpture, 1 setose puncture each side bearing 1 seta ( Fig. 60 ). Labrum rounded, anterior edge outwardly curved with 3 evenly-spaced setae each side. Mentum lobes rounded ( Fig. 12F ), mentum process long and narrow, slightly angled upward (15°), indentation notched ( Fig. 12D ); mentum setae absent. Submentum sclerite constriction narrow with 6–8 setae, 3–4 clustered laterally. Stipes with 2 basal setae. Gula pits small, suture well-defined, gula ( Fig. 8 ) flat with very fine transverse lines. Gena with very fine wrinkles forming an isodiametric pattern across entire area.

Prothorax: Prothoracic carina broad the entire length, slightly crenulated with 5–8 setae each side ( Fig. 60 ), extended to anterior angle; posterior lateral sinuation indistinctly carinate, angled inward; pronotum broad and moderately deflected, overall shape cordate; midline well-defined, posterior medial diamond-shaped impression present, disc without microsculpture ( Fig. 60 ); pronotal foveae narrow and shallow; anterior edge straight and posterior edge inwardly curved medially. Prosternum flat and smooth; proepisternum without microsculpture. Procoxal setae absent; protibia distally expanded and shovel-like ( Fig. 10B ).

Elytra: Broad and moderately deflected, truncated length due to steep angle to apex; humeral angle anteriorly convergent ( Fig. 6A ); basal margin slightly curved and bevelled to base, interval 1 extended to margin; lateral carina narrow in anterior ¾, broadened posterior ⅓, extended to humeral angle; humerus with 4–5 setose punctures; suture ( Fig. 1 ) impressed; all striae with irregularly sized asetose punctures, stria 5 with asetose punctures 2x size of stria 6 asetose punctures; intervals 1–6 slightly convex, intervals 7–9 moderately convex; interval microsculpture present as lines; 7 th strial setal pattern with 2–3 setose punctures in anterior ½, 3–4 setose punctures in posterior ½, setose punctures large; numerous setose punctures in striae on steep slope to apex ( Fig. 60 ); row of many setae above and along length lateral carina.

Ventral surface: Mesepisternum with rugose wrinkles; metepisternum ( Fig. 2 ) without microsculpture; setose punctures on mesocoxae absent and present on metacoxae (1). All abdominal ventrites ( Fig. 2 ) finely lineate laterally; ventrite 3 with 2–4 setose punctures each side of midline (not laterally), ventrite 4 with 3–6 setose punctures each side of midline, may be near lateral margin, ventrite 5 with 5–9 setose punctures each side of midline to lateral margin; ventrite 6 setae present: ♂ with 2 setose punctures distantly spaced along straight apical edge, ♀ with 2 evenly spaced setose punctures each side of midline on bluntly rounded apical edge; lateral foveae absent. Anterior metaventrite process ( Fig. 2 ) a long and narrow triangle with a narrow carina the entire length (may be indistinct).

Male genitalia: Apical portion of penis lobe asymmetrically rounded with a distinct deflection to right of vertical axis (VV) ( Fig. 15A ), ventral edge of apex with symmetrical curve that is curved flatly upward to form slightly forward (of vertical axis) dorsal curve (LV) ( Fig. 60 PL); shaft of penis lobe broad and shortened, shaft straight (VV); 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 rounded; dorsal form of the apex of the central spicule short and narrow; relative extent of setae (scales) of the apical plate sparse (1–25%); size of left setose flange very small; size of right setose flange large. Left paramere basal lobe rounded, narrowly rectangular, short anterior slope to arm; arm long and narrow ( Fig. 60 LP); terminal lobe indistinct from arm, terminus narrowed with apical tuft of sparse medium-lengthed setae ( Fig. 60 LP); sparse short setae along strongly curved ventral edge for ¾ of length. Right paramere long, very narrowly rectangular, narrowed to terminus ( Fig. 60 RP) with a double row of long setae extended along apical ¾ of ventral edge.

Female genitalia: Basal gonocoxite 1 long and narrow, ventral surface with a few rugose wrinkles, internal dorso-lateral carina without setae. Gonocoxite 2 ( Fig. 5 ) long and narrow, bluntly, rounded triangle with egdes reflexed, ventral surface with numerous sensilla pits and short seta posterior to apex on ventral surface (near base of gonocoxite 2). Ramus short and narrow.

Comments: Mecodema tibiale seems to have the narrowest of distributions in comparison to the other former Metaglymma species, Mecodema aberrans and M. monilifer . This species was described by Castelnau who designated four syntypes, all of which were collected from the type locality, here we designate a lectotype and three paralectotypes from this material.

Distribution: New Zealand, South Island only, Central Otago (CO), Dunedin (DN), Southland (SL).

Lectotype: MCNG specimen labelled. Riv. Molyneux, N. Zelanda. Coll. Castelnau [hw, black square border] / Typus [red font, red square border] / Maoria tibiale Cast. [hw] / tibiale Cast. [hw, black square border] / SYNTYPUS Maoria tibalis Castelnau, 1867 [hw, red label] / LECTOTYPE Maoria tibialis Castelnau , Mecodema tibiale design. by DS Seldon, TR Buckley 2019 [red label] / Museo Civico di Genova.

Paralectotypes: 3, label data same as lectotype.

Material examined: 1, NCant. Dunedin N. Zeland Coll. Castelnau [hw, black square border] / Museo Genova Maoria tibialis [hw] Coll. Castelnau (MCNG); 1♂, 1♀, NEW ZEALAND CO, Cromwell-Alexandra terrace 16.NOV.1977, J.C. Watt [hw] / On ground at night [hw] ( NZAC); 1♂ , Kyeburn Ck, Naseby Otago 8 Nov 68 J.I. Townsend ( NZAC); 1♀ , Kyeburn Ck, Naseby Otago 8 Nov 68 J.I. Townsend / NZAC04004586 .

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 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 60. Mecodema tibiale 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.