Irenimus thoracicus 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 : 24-25

7. Irenimus thoracicus Brown , new species

Figures 13, 14 , 27, 28 , 40 , 79, 80, 81, 82, 83, 84 , 86

Diagnosis. Medium to large species, lens shaped, grey. Scape with appressed scales. Pronotum widest anteriorly, lateral margins subparallel in posterior 1/4.

Distinguished from I. duplex by the shape of the pronotum ( Figure 40 ).

Description. Body length 5.21 mm to 6.27 mm (X = ̄ 5.79 mm, s = 0.42, n = 7). Integument black. Dorsum densely covered with light greyish brown appressed scales; elytral declivity occasionally slightly paler, lined anteriorly with an obscure darker line. Femora unicolorous, concolorous with elytra. Tarsi integument strong reddish brown. Rostrum. Length 1.16 mm to 1.36 mm (X = ̄ 1.26 mm, s = 0.09, n = 6), width 0.76 mm to 0.90 mm (X = ̄ 0.83 mm, s = 0.05, n = 6), length/width ratio 1.36 to 1.62 (X = ̄ 1.51, s = 0.10, n = 6). Epifrons with appressed scales overlapping, elongate scales claviform, decumbent, dark; medial and lateral carinae evident. Dorsal carina arched over antennal insertions. Lateral area of antennal insertions with thick setae and appressed scales. Antennae. Scape when in repose reaching hind margin of eye; covered with appressed scales and setae. Funcular segments loosely articulated; segments 1 and 2 clavate, subequal, 1.4 times longer than segment 3; segment 3 clavate, 1.3 times longer than segment 4; segments 4 to 7 clavate, subequal. Head. Eyes ovate. Pronotum. Length 1.67 mm to 1.90 mm (X = ̄ 1.78 mm, s = 0.08, n = 6), width 1.75 mm to 2.00 mm (X = ̄ 1.88 mm, s = 0.11, n = 6), length/width ratio 0.85 to 1.03 (X = ̄ 0.95, s = 0.07, n = 6); widest in anterior 1/3, lateral margins evenly curved in anterior 3/4, subparallel in posterior 1/4 ( Figure 40 ). Anterior margin entire, posterior margin evenly curved. Disc topography evenly convex, occasionally with slight postero-lateral depressions; appressed scales tessellate, domed; elongate scales setiform, semi-erect to decumbent, neutral. Postocular lobes moderately developed. Anterior transverse groove weak beyond level with ventral margin of eye. Posterior transverse groove poorly developed. Lateral posterior margin with obtuse inflection 1/3 of the way down. Elytra. Length 3.29 mm to 3.91 mm (X = ̄ 3.70 mm, s = 0.24, n = 6), width 2.11 mm to 2.85 mm (X = ̄ 2.52 mm, s = 0.32, n = 6), length/width ratio 1.35 to 1.66 (X = 1.48, s = 0.11, n = 6). Anterior margin curved posteriad, humeral angles rounded. Appressed scales narrowly overlapping. Elongate scales claviform, decumbent, largely neutral on disc, pale laterally and posteriorly. Striae moderately impressed; interstriae flat. Elytral apex square in males, ventrally produced in females. Thoracic ventrites. Mesoventral process truncate. Metaventrite densely clothed with appressed scales. Abdomen. Ventrites densely clothed with inner vestiture composed almost exclusively of appressed scales. Apex broadly rounded. Males with ventrite 1 slightly depressed medially, ventrite 5 shallowly concave. Female with ventrite 1 flat, ventrite 5 with medial furrow. Legs. Metafemora with posterior face entirely scaled. Metatibiae with corbel present, narrow, bare; ventral margin of tibial apex entire; males with long, silky hairs on distal half. Male genitalia. Figures 79, 80 . Penis with apex acute; dorsal plate narrowed medially. Endophallus long, reaching to temonal apex; possessing numerous large, toothed proximal sclerites; aggonoporial sclerite with short anterior lobes and long posterior lobes. Female genitalia. Figures 81–84 . Sternite 8 with blade elongate. Styli elongate. Vagina not sclerotised. Bursa copulatrix long, two large triangular sclerites present. Spermatheca slender; ramus slightly produced, divergent with corpus. DNA Sequences: No DNA sequences obtained.

Type material examined. Holotype. Male ( NZAC). Specimen entire, mounted on card triangle. Labelled ‘ Oamaru / 3.3.65 / J. Richards / Ryegrass’ [handwritten, white card], ‘ Irenimus taxonomy / and systematics / SDJ Brown / PhD Thesis 2012–2015 / IRE6259’ [printed, off-white card], ‘ NZ Arthropod / Collection , NZAC / Private Bag 92170 / AUCKLAND / New Zealand’ [printed, yellow card], ‘ HOLOTYPE / Irenimus / thoracicus / Brown 2016’ [printed, red card].

Paratypes. A total of 12 specimens (5 males, 7 females) designated as paratypes, bearing blue paratype label. Paratype specimens deposited in BMNH, LUNZ, NZAC.

DN: Oamaru [-45.0888, 170.9808, A], 3 Mar 1965, Richards J, Ryegrass (BMNH: 2, LUNZ: 2, NZAC: 8).

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

DN: Oamaru.

Elevational range. Label data: no elevation data recorded. Georeferenced data: 7 m to 7 m (X = ̄ 7 m, s = 0, n = 13).

Etymology. The species epithet refers to this species’ distinctive pronotal shape.

Biology. This species is only known from specimens taken in a single collecting event from ryegrass ( Lolium perenne L.).

Figures

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

FIGURE 86. Distributions of Irenimus duplex (circles), I. parilis (squares) and I. thoracicus (triangles).

FIGURES 9 – 14. Habitus photographs of Irenimus males. 9, 10: I. duplex. 11, 12: I. parilis. 13, 14: I. thoracicus, holotype. Scale bars = 1 mm.

FIGURES 23 – 28. Habitus photographs of Irenimus females. 23, 24: I. duplex. 25, 26: I. parilis. 27, 28: I. thoracicus. Scale bars = 1 mm.

FIGURES 39 – 40. Pronotum, dorsal view with head to top of image. 39, Irenimus duplex; 40, Irenimus thoracicus.

FIGURES 79 – 84. Genitalia of Irenimus thoracicus. 79, penis, dorsal view; 80, aedeagus, lateral view; 81, tergite 8, dorsal view; 82, ovipositor, dorsal view; 83, ovipositor and spermatheca, lateral view; 84, sternite 8, ventral view. Scale bars = 0.5 mm; 79, 80 at same scale; 81 – 84 at same scale.