Irenimus Pascoe, 1876

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 : 5-7

Irenimus Pascoe, 1876

Irenimus Pascoe, 1876:54 . Synonymised with Catoptes Schönherr by Sharp, 1886:422. Reinstated by Kuschel, 1969:799. Type species: Irenimus parilis Pascoe, 1876:54 , by monotypy. Gender: masculine.

Diagnosis. Integument densely covered with round or oval appressed scales. Rostrum short and stout, around 1.5 times longer than wide; subparallel proximally. Epistome indistinctly differentiated from frons. Scrobes lateral. Ventral curvature of head angulate. Elytra without tubercles or protuberances. Metanepisternum narrow, suture complete. Metafemora without sharp demarcation between scaled and unscaled regions on posterior surface. Metatibiae with a narrow to wide corbel and a distinctively shaped, angulate apical comb ( Figures 29–33 ). Penis with a sclerotised dorsal membrane.

Differential diagnosis. Species of Irenimus can be distinguished from other New Zealand weevils by the combination of characters given above. The indistinct epistome and angulate ventral head curvature distinguishes them from Catoptes , which have a distinctly demarked epistome and a rounded ventral head curvature, with the angle between head and rostrum approximately 140°. The complete metanepisternal suture and the form of the metatibial apex distinguish Irenimus from Chalepistes , which has the metanepisternal suture invisible, a simple metatibial apex, and a sharply demarked bare area on the posterior surface of the metafemora. The convex elytral disc and lack of elytral tubercles or prominences distringuish Irenimus from Inophloeus villaris Pascoe and allied species which have a flat elytral disc, formed by a subcarinate interstriae 7, and strong protuberances on interstriae 5 above the declivity. The wide, readily visible metanepisternum and the discrete appressed scales on the elytra distinguish Irenimus from Protolobus , which has a very narrow metanepisternum that is often obscured by the lateral margin of the elytra and has dull, strongly overlapping, inseparable appressed scales on the elytra. The proximally subparallel rostrum and laterally situated scrobes distinguish Irenimus from Haplolobus and Nicaeana , both of which have proximally expanding rostra and dorsally situated scrobes.

Description. Body length ranging from 3.2 mm to 6.9 mm. Densely covered with scales on all surfaces. Rostrum. Subparallel proximally, abruptly widened at antennal insertions. Epistome plurisetose, slightly raised above frons but indistinctly differentiated. Epifrons with longitudinal medial carina, lacking sulci; continuous with occiput, without distinct dorsal separation between head and rostrum. Antennae. Sockets dorsolateral, sited in apical 1/3 of rostrum. Scape clavate, reaching to or exceeding the middle of the eye. Funicular segments clavate, subspherical or oblately spheroid, moderately to loosely articulated, segment 7 almost as wide as club. Club two times longer than wide, tapering apically. Head. Width of vertex between eyes greater than width of rostrum. Eyes large, lateral, flat, ovate to subcircular with long axis vertical, parallel with sagittal axis. Ventral curvature of head and rostrum angulate, approximately 90°. Pronotum. Disc smooth, evenly convex. Postocular lobes poorly to well developed, vibrissae present. Elytra. Approximately parallel-sided in anterior 2/3. Elongate scales arising from interstriae. Elytral declivity rounded. No interstriae formed into tubercles, at most a slight swelling on interstria 3 above the elytral declivity. Ventral margin sinuous, highest point around level of metacoxae. Thorax. Procoxae contiguous. Prosternum visible behind procoxae as a raised tubercle (“prosternellum”). Metaventrite with medial suture visible only as a small, circular fovea posteriorly. Abdomen. Ventrites 1 and 2 fused, ventrites 3 to 5 free. Ventrite 1 and 2 subequal in length at midpoint; ventrites 3 and 4 subequal in length, approximately 0.5 times length of ventrites 1 and 2; ventrite 5 approximately equal in length to ventrites 1 and 2. Suture separating ventrites 1 and 2 curved anteriorly at midpoint, other sutures straight. Wings. Absent. Legs. Uniformly and densely covered with appressed scales and setae, except for the posterior surface of the metafemora. Femora unarmed, maximum depth around distal 1/4. Tibiae with indistinct denticles along ventral margin of protibiae and mesotibiae; mucrones present on protibiae and mesotibiae; protibiae wider in distal 1/3 than proximal 1/3, incurved at apex; metatibiae with subparallel dorsoventral margins; apical comb angulate with pale setae; corbel present, narrow to wide, bare. Tarsi with long, coarse setae on dorsal surface, without appressed scales; underside with short, dense setae forming pads. Claws simple, separate, diverging. Male genitalia. Hemisternite 8 divided, with a paired membranous lobe on the anterior margin of the membrane joining the two halves. Penis tubular, strongly curved; lateral lobes separated dorsally by sclerotised dorsal membrane extending from ostium to anterior margin ( Figure 41 , dm); temones longer than penis. Endophallus moderate in length, usually reaching anterior 1/3 of temones when in repose; armed with large aggonoporial sclerite, other sclerites variably present. Tegmen with ring complete; parameroid lobes well-developed; manubrium shorter than temones. Female genitalia. Sternite 8 with spiculum ventrale over 2.5 times as long as blade. Gonocoxite divided into two parts; proximal gonocoxite around 2.6 times longer than distal gonocoxite, largely unsclerotised except for strongly sclerotised rod; distal gonocoxite lightly sclerotised. Bursal sclerites present or absent, numbering 2 if present.

Distribution. All species found in Canterbury and Otago, South Island, New Zealand, with a disjunct population of I. parilis in the central North Island.

Etymology. Pascoe (1876) did not explain how the name was derived. It may have come from the Greek eirene, meaning ‘peace’, and the Latin suffix -imus meaning ‘having the quality of’.

Remarks. The extensive dorsally sclerotised membrane of the penis is a strong apomorphy for Irenimus . However, all external characters that distinguish the genus are considered plesiomorphic.

Figures

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 41 – 46. Genitalia of Irenimus aniptus. 41, penis, dorsal view, al—anterior lobe of aggonoporial sclerite, dmsclerotised dorsal membrane, pl—posterior lobe of aggonoporial sclerite; 42, aedeagus, lateral view; 43, tergite 8, dorsal view; 44, ovipositor, dorsal view; 45, ovipositor and spermatheca, lateral view; 46, sternite 8, ventral view. Scale bars = 0.5 mm; 4 1, 42 at same scale; 43 – 46 at same scale.