Irenimus minimus Brown

Brown, Samuel D. J., 2017, A revision of the New Zealand weevil genus Irenimus Pascoe, 1876 (Coleoptera: Curculionidae: Entiminae), Zootaxa 4263 (1), pp. 1-42 : 18-20

4. Irenimus minimus Brown , new species

Figures 7, 8 , 21, 22 , 29 , 59, 60, 61, 62, 63, 64 , 85

Diagnosis. Small species, oval, grey to dark brown. Scape with appressed scales. Pronotum broadly subquadrate, lateral margins subparallel medially. Elytra with elongate scales setiform, erect; appressed scales tessellate. Females with ventrites simple, ventrite 5 swollen medially. Posterior face of metafemora covered with metallic scales.

Description. Body length 3.16 mm to 3.56 mm (X = ̄ 3.33 mm, s = 0.20, n = 4). Integument black. Dorsum densely covered with light reddish brown appressed scales, with scattering of pale scales on disc of elytra; inconspicuous darker maculae on interstriae 3 at top of elytral declivity. Femora with distal 1/4 paler than proximal 3/4. Tarsi integument deep orange. Rostrum. Length 0.64 mm to 0.67 mm (X = ̄ 0.66 mm, s = 0.01, n = 4), width 0.43 mm to 0.47 mm (X = ̄ 0.45 mm, s = 0.02, n = 4), length/width ratio 1.40 to 1.56 (X = ̄ 1.46, s = 0.07, n = 4). Epifrons with appressed scales tessellate; elongate scales setiform, erect, neutral; medial and lateral carinae not evident. Dorsal carina not arched over antennal insertions. Lateral area ventrally of antennal insertions with fine setae, without appressed scales. Antennae. Scape when in repose reaching hind margin of eye; covered with appressed scales and setae. Funicular segments moderately articulated; segment 1 clavate, 1.3 times longer than segment 2; segment 2 clavate, around 2 times longer than segment 3; segments 3 to 4 clavate, subequal; segments 5 to 7 subspherical, subequal. Head. Eyes subcircular. Pronotum. Length 1.05 mm to 1.16 mm (X = ̄ 1.12 mm, s = 0.05, n = 4), width 1.10 mm to 1.32 mm (X = ̄ 1.22 mm, s = 0.10, n = 4), length/width ratio 0.88 to 0.95 (X = ̄ 0.92, s = 0.04, n = 4); widest in middle, lateral margins abruptly broadening to anterior 1/4, subparallel until posterior 1/4, abruptly constricting to base. Anterior margin entire, posterior margin evenly curved. Disc topography evenly convex; appressed scales tessellate, dull, domed; elongate scales setiform, erect, neutral. Postocular lobes poorly developed. Anterior transverse groove weak beyond level with ventral margin of eye. Posterior transverse groove weak. Lateral posterior margin evenly curved. Elytra. Length 2.05 mm to 2.36 mm (X = ̄ 2.21 mm, s = 0.15, n = 4), width 1.40 mm to 1.78 mm (X = ̄ 1.62 mm, s = 0.17, n = 4), length/width ratio 1.28 to 1.50 (X = ̄ 1.36, s = 0.10, n = 4). Anterior margin strongly curved posteriad, with humeral angles rounded. Disc with appressed scales tessellate; elongate scales setiform, erect, dark on disc, pale laterally and posteriorly. Striae shallowly impressed; interstriae flat. Thoracic ventrites. Mesoventral process rounded in male, acutely rounded in female. Metaventrite densely covered with pappolepida medially, appressed scales laterally. Abdomen. Ventrites with inner vestiture composed roughly equally of pappolepida and appressed scales, pappolepida predominant medially, appressed scales predominant laterally; ventrites 1 and 2 sparsely clothed, ventrites 3 to 5 increasingly sparse. Males with ventrite 1 depressed medially, ventrite 5 shallowly concave. Females with ventrite 1 flat, ventrite 5 flat. Apex of abdomen rounded. Legs. Metafemora with posterior face entirely scaled. Metatibiae with corbel present, narrow, bare; ventral margin of apex slightly emarginate. Male genitalia. Figures 59, 60 . Penis with apex truncate; dorsal plate not narrowed medially. Endophallus possessing numerous small toothed proximal sclerites sited in the penis when in repose; aggonoporial sclerite lacking anterior lobes, posterior lobe fused. Female genitalia. Figures 61–64 . Sternite 8 with blade broad. Styli stout. Vagina sclerotised. Bursa copulatrix short, sclerites absent. Spermatheca slender. DNA Sequences: COI. KX 191228 , KX 191248 , KX191422 . 28S. KX191784 , KX191813 , KX191996 . ArgK. KX191512 , KX191534 , KX191703 . CAD. KX 191152 .

Type material examined. Holotype. Female ( NZAC). Specimen mounted on card teardrop; abdomen removed, dissected and mounted in DMHF on white card below specimen. Labelled ‘ NEW ZEALAND CO / Aldinga Cons. Area / Alexandra / 1 Nov 2012 / SDJ Brown’ [printed, off-white card], ‘ Blower vac sample from / grassland / 45.286°S 169.314°E’ [printed, off-white card], ‘ Irenimus taxonomy / and systematics / SDJ Brown / PhD Thesis 2012–2015 / IRE4861’ [printed, off-white card], ‘ HOLOTYPE / Irenimus / minimus / Brown 2016’ [printed, red card]. Genomic DNA extract from enzyme digestion of abdomen E286 ( NZAC) . CAD sequence KX 191152 ; COI sequence KX191422 ; ArgK sequence KX191703 ; 28S sequence KX191996 .

Paratypes. A total of 3 specimens (1 males, 2 females) designated as paratypes, bearing blue paratype label. Paratype specimens deposited in BMNH, LUNZ.

CO: Clyde Lookout [-45.1942, 169.3044, R], 3 Nov 2012, Brown SDJ, Blower vac sample from herbfield (BMNH: 1, LUNZ: 1); Conroys Rd [-45.2789, 169.3347, R], 1–4 Nov 2012, Brown SDJ, Pitfall trap (LUNZ: 1).

Distribution. South Island:—/ CO /—( Figure 85 ).

CO: Alexandra; Clyde.

Elevational range. Label data: no elevation data recorded. Georeferenced data: 293 m to 323 m (X = ̄ 312 m, s = 13, n = 4).

Etymology. From the Latin minimus , ‘least’, in reference to is small size, being the smallest known species of Irenimus .

Biology. Specimens were collected from short grassland, Raoulia cushionfield, and herbfield dominated by thyme ( Thymus vulgaris L., 1753).

Remarks. This species can be distinguished from other similarly sized entimine weevils in the same locality by the combination of the complete metanepisternal suture, setiform elongate scales on the elytra and pronotum, the dull, domed, appressed scales on the pronotum and the subquadrate shape of the pronotum.

Figures

FIGURE 85. Distributions of Irenimus aniptus (circles), I. crinitus (squares), I. minimus (triangles) and I. stichus (stars).

FIGURES 1 – 8. Habitus photographs of Irenimus males. 1, 2: I. aniptus. 3, 4: I. crinitus. 5, 6: I. stichus, holotype. 7, 8: I. minimus. Scale bars = 1 mm.

FIGURES 15 – 22. Habitus photographs of Irenimus females. 15, 16: I. aniptus. 17, 18: I. crinitus. 19, 20: I. stichus. 21, 22: I. minimus. Scale bars = 1 mm.

FIGURES 29 – 34. Left metatibia, anterior view. 29, Irenimus minimus; 30, Irenimus parilis; 31, Irenimus parilis, apical view; 32, Irenimus duplex; 33, Irenimus duplex, apical view; 34, Chalepistes compressus. Abbreviations: cl – corbel; sc—setal comb; ve—ventral emargination. Drawings not to scale.

FIGURES 59 – 64. Genitalia of Irenimus minimus. 59, penis, dorsal view; 60, aedeagus, lateral view; 61, tergite 8, dorsal view; 62, ovipositor, dorsal view; 63, ovipositor and spermatheca, lateral view; 64, sternite 8, ventral view. Scale bars = 0.5 mm; 5 9, 60 at same scale; 61 – 64 at same scale.