Chrysomelinae, Latreille, 1802

Leschen, Richard A. B., Reid, Chris A. M. & Nadein, Konstantin S., 2020, Generic Review of New Zealand Chrysomelinae (Coleoptera: Chrysomelidae), Zootaxa 4740 (1), pp. 1-66 : 5-6

Chrysomelinae

Diagnosis. Body subovoid to ovoid, sides of body somewhat parallel-sided to rounded, dorsum generally glabrous. Head partly concealed but not covered entirely by pronotum, not constricted behind eyes. Antennal grooves on head present or absent. Antennal insertions not approximate. Pronotum with lateral carina; procoxal cavities open or closed behind. Procoxae ovate and weakly transverse. Tergite VII hidden or almost completely hidden in dorsal view.

Description. Length 1.5–8.0 mm. Body shape predominantly subovoid to ovoid; prothorax and elytra often forming a continuous outline in dorsal view; tergite VII hidden or almost completely hidden in dorsal view. Dorsum brightly uni- or bicoloured or dull, glabrous. Dorsal surfaces usually smooth; pronotal disc often with non-uniform punctation coarser at the base. Head prognathous rarely forming a short muzzle with genae extending a short distance beyond level of antennal and maxillary insertions, retracted into prothorax, not covered entirely by pronotum, not strongly constricted behind eyes; deep grooves absent on the vertex, but postantennal calli and postclypeal lines may be present. Eyes almost circular to strongly transverse-oblong, with or without anterior emargination; flat to strongly protuberant. Clypeus transverse to trapezoidal, anterior margin straight. Genae usually short and not extended greatly beyond mandibular insertions (long in some species of Nanomela ). Antennal insertions exposed from above, and widely separated, postantennal calli present or absent; when not delimited by a line, pale cuticular spots may be present; subantennal grooves absent or present. Frontoclypeal suture present or absent; lateral postclypeal lines present or absent, medial postclypeal line absent. Antennae 11-segmented, filiform, subfiliform, or clavate. Mandibles with two incisors, terebral edge with ( Nanomela ) or without serrate edge, prostheca setose. Pronotum transverse, length usually 2.3–2.5x its width, usually widest at base, lateral pronotal carinae complete, with margin or bead visible from above; each anterior and posterior angle with or without trichobothrium. Procoxal cavities transverse-ovate or rounded, externally open, narrowly opened or closed. Scutellary shield usually triangular and anteriorly rounded (sometimes reduced or absent). Elytra in combination varying in shape from almost circular to elongate, irregularly punctate or with as many as 16 distinct puncture rows; elytral apices concealing all abdominal tergites. Hind wings absent or present but often reduced. Metaventrite with or without subcoxal lines, discrimen and transverse metaventral (metakatepisternal) suture present or absent. Legs with globular to transverse procoxae that are not projecting; femora fusiform to claviform; tibial apices generally widened or clubbed and sometimes weakly dimorphic (e.g., male tibiae are slightly more robust and elbowed); tibial spurs absent; tarsi 5-5-5 or 4-4- 4 ( Nanomela and smaller species of Aphilon lacking tarsomere 4 or tarsomeres 4 and 5 fused) with tarsomere 3 apically bilobed or truncate, first tarsomeres often expanded in males; tarsal claws simple, bifid or appendiculate. Abdomen with five ventrites, free and lacking deep impressions, ventrite 1 generally about twice as long as 2, with or without postcoxal lines; tergite VII usually forming sclerotised pygidium, usually completely hidden by elytra in dorsal view. [Based on Reid 2014]

Comments. The diagnosis and short description above will distinguish New Zealand members of the chrysomelines from other subfamilies occuring in the Pacific region. There are approximately 130 genera, with over 3,000 species, worldwide ( Reid 2017). Two tribes are recognised by Reid (2014), Timarchini and Chrysomelini , the latter variously subdivided into 4–12 subtribes ( Seeno & Wilcox 1982; Daccordi 1994; Bouchard et al 2011), with all of the New Zealand endemic genera being placed into the Phyllocharitini of Daccordi (1994). Details of the composition of the endemic genera are below. The few introduced members of the the mainly Australian subtribe Paropsina (sensu Daccordi 1994) feed on exotic Acacia and Eucalyptus and are ovate with epipleura completely hidden in lateral view ( Fig. 17B , D–F).

Chrysomeline larvae and adults are generally external feeders on plants, feeding on leaves, rarely flowers, and usually, not on pollen. Their plant hosts are usually core eudicots, rosids and asterids, but a few species feed on Bryophyta ( Reid 2017). The host associations of New Zealand endemic species are poorly known because most species are cryptic, ground-dwelling and probably nocturnal. Attempts to obtain additional specimens of poorly collected forest-dwelling taxa by sifting mostly mosses during summer 2018 in the South Island, resulted in additional geographic records but few specimens (i.e., Maurodus ornatus (Broun) and Zeaphilon marskeae , nov. sp.), but confirmed that many species are bryophyte specialists. Larvae are rarely collected and have not been described. The larvae of Aphilon have oddly fused terga and have been collected feeding on liverworts. The single illustration of an undetermined Chalcolampra larva (as Allocharis in Reid [1995] ) shows an individual with a well sclerotised circular plate formed from terga VII–IX indicating burrowing habits and is the same species that has been recorded by Wardle et al. (1971) feeding on the composite Olearia colensoi .

Included genera. Aphilon Sharp, 1876 (endemic), Caccomolpus Sharp, 1886 (endemic), Chalcolampra Blanchard, 1853 (= Allocharis Sharp, 1882 , = Cyrtonogetus Broun, 1915 , syn. nov., = Eualema Broun, 1903 ) (Southeast Asia, Australia and New Zealand), Chrysolina Motschulsky, 1860 (introduced for biological control), Maurodus gen. nov. (endemic), Dicranosterna Motschulsky, 1860 (introduced), Gonioctena Chevrolat, 1836 (in- troduced), Nanomela gen. nov. (endemic), Paropsis Olivier, 1807 (introduced), Paropsisterna Motschulsky, 1860 (introduced), Peltoschema Reitter, 1888 (introduced), Zeaphilon gen. nov. (endemic), Trachymela Weise, 1908 (introduced).

Figures

FIGURES 17A–K. Dorsal habitus of introduced chryomelines and their structures; A, Chrysolina hyperici, length 5.5 mm; B, Dicranosterna semipunctata, length 9.9 mm; C, Gonioctena olivacea, length 3.4 mm; D, Paropsis charybdis, length 10.3 mm; E, Peltoschema mansueta, length 3.2 mm; F, Trachymela sloanei, length 8.0 mm; G, Dicranosterna semipunctata, lateral view of maxillary palpus; H, Paropsis charybdis, ventral view of maxillary palpus; I, Trachymela sloanei, ventral view of palpus; J, Paropsis charybdis, ventral view of prosternum; K, Paropsis charybdis, left lateral view of pronotum.