Chalepistes 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 : 34-35

Chalepistes Brown , new genus

Type species: Catoptes compressus Broun, 1880:429 , here designated. Gender: masculine.

Diagnosis. Integument densely clothed with appressed and elongate scales, appressed scales generally discrete. Rostrum short and stout, less than two times longer than wide. Epistome indistinctly differentiated from frons by sculptural differences. Frons with sparse setae, unscaled. Scrobes lateral. Ventral head curvature angulate. Eyes flat. Ocular lobes present, occasionally inconspicuous. Metanepisternal sutures absent. Posterior face of metafemora usually with large bare area proximally and sharp demarcation between this and the scaled area in the distal 1/4. Metatibiae with apex simple or with narrow, bare corbel; apical comb arcuate ( Figure 34 ). Penis with dorsal membrane unsclerotised.

Differential diagnosis. Chalepistes is very similar to Irenimus and the comparisons between Catoptes , Inophloeus villaris , Haplolobus and Nicaeana in the differental diagnosis to Irenimus given above apply also to Chalepistes . Although the complete absence of metanepisternal sutures in Chalepistes readily distinguishes the genus from Protolobus , the extremely narrow metanepisternum of the latter makes this character difficult to use in practice. The combination of small size (<3.5 mm), densely scaled posterior face of the metatibiae, barely separable elytral appressed scales, a scape densely clothed with large appressed scales and a densely scaled frons will distinguish Protolobus species from Chalepistes .

Description. Body length ranging from 2.5 mm to 9.5 mm. Densely covered with scales on all surfaces, appressed scales usually obvious, discrete, round, ribbed; but with variations in the degree of separability, size and sculpture. Rostrum. Subparallel proximally, abruptly widened at antennal insertions. Epistome plurisetose, slightly raised above frons but separation indistinct. Epifrons 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; clothed with setae and occasionally with small, inconspicuous appressed scales. 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 topography variable, usually 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 or angulate. Interstriae variably formed into tubercles above the elytral declivity, usually more pronounced in females; interstria 3 most frequently tuberculate, but tubercles can also be formed on the elytral suture and on interstria 5. Ventral margin sinuous, highest point around level of metacoxae. Thorax. Procoxae contiguous. Prosternum visible behind procoxae as a raised tubercle. 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. Males usually with ventrite 1 depressed to a greater or lesser extent, ventrites 4 and 5 simple. Females with ventrite 1 flat; the posterior margin of ventrite 4 usually entire, sometimes produced into a lamina that covers ventrite 5; disc of ventrite 5 often modified with swellings, tubercles or furrows. 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, mesotibiae and occasionally metatibiae; mucrones present on protibiae and mesotibiae, occasionally on the metatibiae in males; protibiae wider in distal 1/3 than proximal 1/3, incurved at apex; apical comb arcuate, with pale setae; corbel present or absent, narrow, bare or covered with scales. Tarsi with long, coarse setae on dorsal surface, without appressed scales; underside with short, dense setae forming pads. Claws simple, separate, diverging. Male genitalia. Penis tubular, strongly curved; lateral lobes usually separated dorsally, occasionally fused; dorsal membrane unsclerotised; 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 2.7 times longer than distal gonocoxite, largely unsclerotised except for strongly sclerotised rod; distal gonocoxite lightly sclerotised. Bursal sclerites usually present, numbering either 2 or 4.

Distribution. Found throughout New Zealand, with most species found occurring south of Canterbury.

Etymology. Derived from the Greek chalepos, ‘difficult, troublesome’, and the suffix -pistes, denoting agency, together forming ‘trouble bringer’ in reference to the convoluted taxonomic history of the genus.

Remarks. Chalepistes has few clear apomorphies not shared by other genera. The lack of metanepisternal sutures is the clearest external apomorphy uniting the members of the genus; however, this loss is frequently seen in apterous weevils and is an unreliable character for inferring higher relationships. The strongly demarked unscaled region on the metafemora also appears to be an apomorphic character, however this is not shared by all species of the genus.

Descriptions, type details, new species and a key to the species of Chalepistes will be the subject of a forthcoming monograph. In the interim, the following combinations and synonyms are proposed.

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.