Mecodema godzilla, Seldon & Buckley, 2019

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 : 51-53

Mecodema godzilla sp. n.

Figure 29 .

Diagnosis: Can be distinguished from other North Island Mecodema species by: 1, its size (34–36 mm long and 11.5–13 mm wide); 2, elytra truncated by steep apical slope; 3, lateral carina broad and reflexed upward the entire length.

Description: Length 34.3–36.4 mm, pronotal width 10.1–11.2 mm, elytral width 11.7–12.9 mm. Colour of head and pronotum black to glossy black, elytra matte reddish-brown to matte black, ventrally (including legs) brown to matte black.

Head: Very broad, slightly deflected laterally. Vertex smooth, except for very fine lines forming an isodiametric pattern laterally; vertexal groove defined by shallow depressions and punctures laterally ( Fig. 29 ); small supraorbital puncture bearing 4–5 setae; supraorbital grooves absent; frons ( Fig. 9 ) medially convex with a large and shallow depression each side of midline, grooves may be present; frontoclypeal suture and tentorial pits indistinct; anterior area of clypeus with 3 shallow and broad grooves, 1 large setose puncture each side and 1 medial puncture all bearing 2 setae. Labrum rectangular, anterior edge outwardly curved with 2 proximate central setae, 2 setae each side evenly spaced. Mentum lobes rounded ( Fig. 12F ), median process short and very broad, upward angle absent, very strongly indentate ( Fig. 12A ); mentum setae absent. Submentum sclerite constriction broad with 4–6 setae evenly spaced. Stipes with 2 basal setae. Gula pits small, suture indistinctly impressed, gula flat with fine transverse lines. Gena ( Fig. 8 ) with fine wrinkles forming an isodiametric pattern across entire area.

Prothorax: Prothoracic carina ( Fig. 11 ) broad the entire length (very broad and flattened at shoulder), slightly crenulated with 8–10 setae each side, extended beyond anterior angle; posterior lateral sinuation evidently carinate, angled outward ( Fig. 29 ); pronotum broad and flat but deflected laterally, overall shape broadly cordate; midline slightly impressed, anterior medial triangular impression and posterior medial diamond-shaped impression present, disc with closely-spaced transverse wrinkles laterally, anterior with a rolled-edge and fine-line microsculpture; pronotal foveae broad and deep (causing pronotum to appear pinched, especially at midline); anterior and posterior edges curved. Prosternum ( Fig. 2 ) concave with fine transverse lines laterally; proepisternum without microsculpture. Procoxal setae absent; protibia distally expanded and shovel-like ( Fig. 10B ).

Elytra: Broad and moderately deflected (widest at midpoint), shortened with steep slope to apex, overall shape ovate; humeral angle evenly convex ( Fig. 6B ); basal margin slightly curved and gently sloped to base, interval 1 extended to base; lateral carina broad and reflexed upward the entire length, extended to humeral angle; humerus with 2–3 setose punctures within angle ( Fig. 29 ); suture slightly impressed; striae 1–4 with very small, regularly spaced asetose punctures, slightly increased in size laterally; intervals 1–4 flat, intervals 5–9 moderately convex; intervals with strong transverse lines, especially laterally; 7 th strial setal pattern with 3–4 setose punctures in anterior ½, 4 setose punctures in posterior ½, setose punctures small.

Ventral surface: Mesepisternum and metepisternum with wrinkles and sparse punctures; setose punctures present on mesocoxa (2) and metacoxa (3). All abdominal ventrites ( Fig. 2 ) finely lineate, ventrites 1–3 with obsolescent punctures; ventrites 3–5 with 1 setose puncture each side of midline; ventrite 6 setae present: ♂ with setose punctures absent and a straight apical edge; ♀ with 3–4 setose punctures each side, 2 proximate medially, 2 close to junction of blunt-rounded apical edge and curve anterad; lateral foveae absent. Anterior metaventrite process a long pointed triangle with a well-defined and narrow carina the entire length.

Male genitalia: Apical portion of penis lobe asymmetrically hooked with a deflection to right of vertical axis only pronounced (moderately) in dorsal process (VV); ventral process a short and bluntly rounded point (perpendicular to shaft), apex curved flatly upward to form the dorsal process that is a short and broad hook with a brief and bluntly recurve to shaft ( Fig. 29 PL); penis lobe shaft is narrow the entire length, ventral edge moderately curved to right especially apically (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 rounded; dorsal form of the apex of the central spicule greatly expanded with projection; setal (scales) coverage of the apical plate extensive (76–100%); size of left setose flange small; size of right setose flange absent. Left paramere basal lobe ovate and relatively small with very steep slope (90°) to arm; arm short and broad, narrowed towards terminal lobe ( Fig. 29 LP); terminal lobe short and narrow, only a few very short setae at apex; medium length comb of setae at midarm, sparse short setae extend along apical ⅓ of ventral edge; ventral edge curved. Right paramere a relatively broad triangle, gradually narrowed to apex, a double row of long setae extended along apical ¾ of ventral edge ( Fig. 29 RP).

Female genitalia: Basal gonocoxite 1 short and broad, apically flattened, a few deep broad grooves present on ventral surface, internal dorso-lateral carina with 2 setae. Gonocoxite 2 ( Fig. 5 ) short and broad, squared triangular, exterior edge straight (90°), apically curved upward. Ramus long and narrow.

Comments: The left and right parameres of M. godzilla and M. validum (Mt Ruapehu type locality) are very similar, but the apical portion of the aedeagus is significantly different.

Distribution: New Zealand, North Island, Mt Ruapehu, Lake Surprise.

Holotype: AMNZ male labelled. Ruapehu 7000–8000ft 18.IV.1964 D. Faram [hw] / M.B. Paterson Collection / HOLOTYPE Mecodema godzilla n. sp. design. DS Seldon, TR Buckley 2018 [red label] / AMNZ 40839 [green label] .

Paratype: LUNZ female labelled. NEW ZEALAND , TO, Mt Ruapehu, L. Surprise 1370m 15.xii.85 / R.M. Emberson P. Syrett under log Nothofagus solandri / LUNZ00002704 .

Etymology: Named for the giant mythical monster of Japan. Godzilla is a non-latinised word so spelling remains invariant.

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 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 29. Mecodema godzilla 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.