Mecodema antarctica Castelnau 1867, comb. n.

Mecodema antarctica Castelnau, 1867, comb. n.

Figure 17.

Brullea antarctica Castelnau, 1867.

Diagnosis: Mecodema antarctica is distinguishable from all other North Island Mecodema species by having: 1, greatly expanded protibia and mesotibia; 2, ventrites with numerous setose punctured; 3, pronotum and elytra truncated; all adaptations for a psammaphilous lifestyle.

Description: Length 20–28 mm, pronotal width 6.5–8.3 mm, elytral width 7.7–9.9 mm. Colour of entire body deep reddish-bronze to glossy black.

Head: Narrow and convex laterally (Fig. 14D). Vertex smooth, some very fine transverse wrinkles may be present laterally (Fig. 17); vertexal groove defined by broad and shallow depressions laterally, otherwise smooth; small supraorbital punctures bearing 2 setae; a single shallow supraorbital groove in front of eye, a few very small wrinkles mesad eye may be present; frons smooth; frontoclypeal suture a very narrow groove, very small tentorial pits; anterior area of clypeus with a very shallow depression each side of midline; clypeus with 1 setose puncture laterally, bearing a single seta. Labrum rectangular, laterally rounded with anterior edge straight to slightly outwardly curved with 2 proximate central setae, 2 setae each side evenly spaced. Mentum lobes squared, median process very short and broad, upward angle absent, deeply indentate (Fig. 12A); setose punctures variably present or absent. Submentum sclerite constriction narrow with 6 setose punctures evenly spaced. Stipes with 2 basal setae. Gula pits small in deep recess, suture very narrow (difficult to define on darker specimens), gula flat and smooth. Gena with a very fine isodiametric pattern laterally.

Prothorax: Prothoracic carina narrow the entire length, smooth to weakly crenulated with 3–4 setae each side (Fig. 17), extended beyond anterior angle; posterior lateral sinuation indistinctly carinate, parallel; pronotum broad and rounded laterally, edges angled inward laterally to head forming overall orbicular shape (truncated); midline (Fig. 11) well-defined, medial impressions absent, disc with fine transverse wrinkles laterally (Fig. 17); pronotal foveae broad and very shallow; anterior edge slightly inwardly curved, posterior edge curved postero-laterally forming a moderate curve medially. Prosternum flat and smooth; proepisternum without microsculpture; Procoxal (Fig. 2) setae absent; protibia greatly distally expanded and shovel-like (Fig. 10A), apical spur greatly dilated; profemur shortened and broad.

Elytra: Broad, rounded and truncated, almost ovate in shape, distinctly deflected laterally; humeral angle anteriorly convergent (Fig. 6A); basal margin slightly curved and bevelled to base (intervals and striae truncated at margin); lateral carina very narrow the entire length, extended to humeral angle, lateral carina setae in deep punctures (clearly visible); humerus with 1 anterior setose puncture, 2 evenly spaced posterad (some variation in number of setae present); suture defined by interval 1 extended to scutellum; striae 1–4 with obsolescent punctures, striae 5–6 punctures slightly increased in size, but indistinctly impressed, striae 7–8 with larger pits, (may be starshaped); intervals 1–3 weakly convex, increasingly convex laterally (intervals 4–9); interval microsculpture absent; 7 th strial setal pattern with 1–2 setose punctures in anterior ½, 3–4 setose punctures in posterior ½, all setose punctures in broad pits.

Ventral surface: Mesepisternum and metepisternum without microsculpture; setose punctures of mesocoxae (1) and metacoxae present (2), large shallow foveae present on metacoxae; mesofemur and metafemur shortened and broad, mesotibia shortened and apical spur dilated; metatibia shortened, greatly curved outwardly, apical spur dilated. Abdominal ventrites 1–5 smooth; ventrite 3 with 2 setose punctures in shallow depression each side (not laterally), ventrite 4 with 5–9 setose punctures in shallow depressions each side (midline to sides with gap), ventrite 5 with 9–10 setose punctures in shallow depression each side; ventrite 6 setae present: ♂ with 6–7 short grooves along straight apical edge, ♀ with 3–6 setae on each side along a rounded apical edge; ventrites foveate laterally. Anterior metaventrite process rounded at apex and deeply concave and without carina.

Male genitalia: Apical portion of penis lobe symmetrically rounded (Fig. 17 PL), evenly curved dorsally without a deflection to the right of vertical axis (VV); shaft of penis lobe broadened toward base (midpoint broader than base), moderately curved entire length (VV), overall length of penis lobe shortened and straight (LV) (Fig. 17 PL). 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 narrow and short; setal (scales) coverage of the apical plate is sparse (1–25%); left setose flange is small, right setose flange is large. Left paramere basal lobe rectangular with slight anterior hump, short slope forming a very broad arm that narrows gradually to a large terminal lobe (Fig. 17 LP), arm and lobe inwardly curved across penis lobe; terminal lobe with a tuft of long setae, short and sparse setae extended apically along ¾ of length; ventral edge of basal lobe straight (Fig. 17 LP). Right paramere curved, narrowly triangular (¾ width of left paramere), apex with tuft of long setae, short and sparse setae extended along apical ¾ along ventral edge (Fig. 17 RP), inwardly curved toward penis lobe.

Female genitalia: Basal gonocoxite 1 (Fig. 5) short and narrow, ventral surface glaborous, sensillar pits present; inner surface grooved, internal dorso-lateral carina with setae absent. Gonocoxite 2 paddle-like, apex bent outward, with sensillar pits present. Ramus long (over ½ length of gonocoxite 1) and broad.

Comments: The greatly distally expanded protibia and mesotibia are probably used for burrowing into sand. The shortened length of the abdomen and the increased number setae on the ventrites are presumed to reduce wear on the dragging abdomen. All are characters associated with species adapted to dwelling on sand dune systems.

Distribution: New Zealand, North Island: mostly west coast (but some east coast areas) sand dune systems from Northland, Auckland, Waikato, Gisborne, Taranaki, Wanganui, Wellington; South Island: Nelson, Westland.

Holotype: MCNG specimen labelled. Auckland Coll. Castelnau [hw, black square border] / Brullea antarctica Cast. [hw] / Typus [red font, red square border] / antarctica Cast. [hw, black square border] / HOLOTYPUS Brullea antarctica Castelnau, 1867 [hw, red label] / Museo Civico di Genova.

Material examined: 1♂, NEW ZEALAND ND Te Paki Res, Te Paki Stream 50m, 15.II.1995 Larivière, Larochelle / Sand-dunes: open, bare yellow soil; 1♀, NEW ZEALAND AK Helensville 14.II–18.III.1993 A. Larochelle. M-C Larivière / sandy vacant lot pittraps; 1, Waikawa Beach, S. of Levin, 20.X.96, J.I.Townsend [hw] / J.I. Townsend Collection / NZAC04006420; 1♀, In sand dunes Waitarere Beach 13.1.80 J.I.Townsend [hw] / J.I. Townsend Collection / NZAC04006409; 1♂, NEW ZEALAND Te Werahi Beach sand dune NZMS 260 MO2 957499 dead, Aug 1997 I.A.N. Stringer / J.I. Collection / NZAC04006392.