Geochus Broun, 1882

Leschen, Richard A. B., Davis, Steven, Brown, Samuel D. J., Brav-Cubitt, Talia & Buckley, Thomas R., 2022, The Enigmatic Dead-Leaf Miner Geochus Broun (Coleoptera: Curculionidae): Phylogenetic Placement, a New Species, and Lectotype Designations, The Coleopterists Bulletin 76 (1), pp. 1-35 : 8-12

Geochus Broun, 1882

Geophilus Broun 1880: 445 (non Leach, 1814; nee Schoenherr, 1823; nee Gistl, 1834; nee Selby,

1835; nee Koch, 1847). Type species: Geophilus inaequalis Broun, 1880 , by monotypy.

Geochus Broun 1882: 128 . Replacement name for Geophilus Broun, 1880 . Type species: Geophilus inaequalis Broun, 1880 , by provision of Article 67.8 of the ICZN.

Diagnostic Description. Adult. Rostrum short, inserting into a shallow impression on prosternum between procoxae. Mandible lacking deciduous scar. Metanepisternum partially to fully fused with metaventrite; without sclerolepidia. Mesoventral surface between mesocoxae on the same plane as metaventrite. Ovipositor entirely membranous. Aedeagus with reduced tegmen, with or without parameres. Tibiae lacking mucro, premucro and ascendant comb but having an uncus at the inner margin and apical setae. Onychium and tarsal claws absent or present (present only in a single species).

Larva. Body form flattened. Head with long endo- carinae and reduced chaetotaxy. Spiracles of abdominal segment VIII lateral.

Differential Diagnosis. Adult Geochus are similar to phrynixines but differ from them by having a weak prosternal groove, the meso-metaventrites are at different levels, and the tibiae are not mucro- nate. Tarsomere 5 is absent in all species, apart from the new species described below. Larvae are easily distinguished by the characters listed above (see also May 1993). From other adult Viticiini, Geochus can be distinguished by having an extremely short metaventrite, dorsal surfaces largely denuded and lacking pigmented or reflective scales, and by having a distinct, very compact body shape with the pronotum and elytra tightly joined.

Adult Description. Body compact, somewhat narrow to ovate, often partially dorsoventrally compressed. Color light to dark red-brown, sometimes dark brown to black and bicolored with elytral markings. Cuticle smooth to tuberculate, glabrous to subglabrous; generally with microsculpture; vestiture on dorsal and ventral surfaces absent or consisting of narrow to thickened setae or scales ( Figs. 2E–F , 3E , 4B ); not forming tufts. Head round- ed with genae present but not spinelike; scales on head and rostrum stellate to multi-fimbriate; rostrum relatively short, length shorter than prothorax, without distinct posterior margin, with or without lateral and medial carinae, dorsum of rostrum rugosely sculptured to varying degrees ( Figs. 1 , 2A–B , 3F , 4A , 5B–C , 6E–F ), width wider or narrower than lateral widths of eyes combined; scrobes deep, parallel to rostrum if rostrum long, or oblique and directed towards gular angle on short rostrum. Eyes small and coarsely faceted, lateral. Antennae ( Fig. 7A ) inserted subapically or at middle of rostrum (distal 1/3 or 1/2); extending to edge of pronotum or slightly shorter; consisting of 11 antennomeres, with scape reaching front margin of eyes, funicle with 7 antennomeres, antennomeres 2 and 3 equal or subequal in length; club 3-segment- ed and elongate, sutures distinct with apical segment short and conical. Mandible lacking deciduous scar ( Figs. 10C–D , 11C–D ); incisor lobe bi- or tridentate. Maxillary and labial palpi ( Figs. 10A–B , 11A–B ) with apical palpi 2× as long as penultimate palpi; prementum somewhat sub-circular. Pharyngeal plate slightly reduced with weak, anteriorly converging posterior arms, completely sclerotized (absence of any holes) with posteriorly projecting lateral margins ( Figs. 10E , 11E–F ). Proventriculus consisting of 6 lamellae. Pronotum narrower than greatest combined width of elytra, sides confluent with elytral outline or not, often constricted in middle or apical third but sometimes parallel-sided, widest at base; anterior margin not strongly constricted, nor extended apicad to form a hood; pos- tocular lobes absent; dorsal surfaces of pronotum and elytra at same level. Prosternum lacking a distinct groove or cephalic rest with sharp lateral edges, but a weak or a distinct depression present; notal projections completely fused or with distinct line. Mesonotum reduced ( Figs. 2C , 4C , 5D–F , 6B , 7B ); mesoscutellum highly reduced to a small bump or weak convexity. Metanotum reduced, weakly sclerotized and membranous. Elytra without humeral callus; with up to 9 deep to weakly impressed punctate striae, smooth or sometimes with distinct ridges or tubercles ( Figs. 2D , 4D , 5E , 6A, C , 7C ), wax duct openings sparsely scattered across surface ( Figs. 2F , 4E , 6D , 7D ). Hind wings highly reduced (brachypter- ous) ( Fig. 10F ). Mesoventrite lacking a rostral groove, length longer or shorter than width of mesocoxal cavity; ventral surface between mesocoxae on same plane as metaventrite. Metanepisternum partially ( Fig. 10F ) to fully ( Figs. 3D–E ) fused with metaventrite; metanepisternum with sclerolepidia absent ( Figs. 3D–E ), but in addition to mesepister- num, covered with stellate/tentacular setae ( Figs. 7E–F ). Metaventrite very short, length about as long as mesocoxal cavity, meso- and metacoxal cavities separated by 1/2 to 2/3 coxal widths.Abdomen long, length about 4 times longer than meso- and metaven- trites combined; ventrites 1 and 2 connate ( Fig. 1B ), transverse suture present or absent at middle; in- tersegmental membranes present between ventrites 2–5; abdominal ventrite 5 of female with or without an apical semicircular fovea. Male terminalia with tergite VIII not divided and very slightly exposed beyond abdominal ventrite 5, short setae present; sternite VIII ( Figs. 8C, E , 9C , 13C, F ) divided into two small elongate sclerites; sternite IX with median deep narrow concavity along posterior margin, forming two posterior lobes; spiculum gastrale ar- ticulate, elongate, weakly asymmetrical and lacking posterior arms, expanded apically, and extending to level of abdominal ventrite 1; aedeagus simple (pedal) ( Figs. 8B , 9A–B , 13A–B, D–E ) penis flattened, having two apical and articulated median struts (temones), struts less than half to slightly greater than half the length of median lobe; tegmen reduced, ring-like, with anterior strut (manubrium); parameres absent or present; ostiolar canal present, well-sclerotized, with two lobes; internal sac with armature in form of minute setiform and scale-like spines, sometimes with sclerotized flagellum. Female with sternite VIII subcircular ( Figs. 9D , 12A–B ), spiculum ventrale symmetrical, with deeply bifurcate base, apex extending to level of abdominal ventrite 2; ovipositor membranous, unsclerotized (lacking gonocoxites and styli), with bursa copulatrix present; spermatheca falciform ( Figs. 9D–E , 12C ), smooth to annular with short accessory gland. Rectal ring of hindgut not observed. Legs with trochanter asetose; femora at most tuberculate; tibiae lacking mucro, premucro, and ascendant comb, but having a spur (uncus) at inner margin and apical setae ( Figs. 3A , 5A ), and protibia sometimes elbowed or toothed. Tibiae not greatly expanded at apex and bearing a single apical spur. Tarsi linear and broad with tarsomeres 2 and 3 slightly wider than tarsomere 1, tarsal formula usually 3-3-3 ( Figs. 4F , 5A ), lacking apical tarsomeres and with tarsomere 3 entire; tarsal formula rarely 5-5-5 ( Figs. 3A–C ), with tarsomere 3 bilobed and tarsomere 5 equal in length to tarsomeres 2 + 3, with unisetose empodium and divergent claws.

Larval Description. See May (1993).

Remarks. A total of 27 species of Geochus has been described, one of which is described here. Most of these species are from New Zealand, including Stewart Island; however, no specimens have been collected from the Subantarctic or the Chatham Islands. Geochus howensis has been described from Lord Howe Island and is the only species known from an Australian territory. Several species remain to be described from New Zealand, including from the Three Kings Islands, a few from Lord Howe Island, and at least one new species from New Caledonia.

We recognize 13 species groups within the species described to date and provide a key to these groups following the species treatments below. Although we have examined all the types, in lieu of careful morphological examination and dissections of similar-looking species from disparate localities, we do not make formal decisions on synonymies between nominal taxa.

Figures

Fig. 2. SEM images, Geochus kuscheli, new species. A) Head (dorso-anterior aspect), B) Enlargement of frons and base of rostrum, C) Mesonotum, D) Left elytron, E) Enlargement of scales on elytron, F) Enlargement of scale, showing canal opening of the wax gland.

Fig. 3. SEM images. Geochus kuscheli, new species: A) Protarsus, showing presence of pretarsal claws (dorsal aspect), B) Protarsus, showing pretarsal claws (ventral aspect), C) Enlargement of spatulate setae on ventral surface of protarsus, D) Pro- and mesothorax, lateral aspect, showing partially fused meta- and metepisterna, E) Enlargement of metepisternum, showing stellate setae/fimbriate scales. F) G. inaequalis, head (dorso-anterior aspect).

Fig. 4. SEM images, Geochus inaequalis. A) Enlargement of frons and dorsal surface of rostrum, B) Enlargement of setae/scales on dorsal surface of rostrum, showing canal openings of wax glands (arrows), C) Mesonotum, D) Left elytron, E) Enlargement of scale on elytron, showing canal opening of the wax gland, F) Protarsus, the arrow indicating absence of pretarsal claw (dorsal aspect).

Fig. 1. Habitus photographs of Geochus kuscheli, new species. A) Dorsal view, B) Ventral view, C) Lateral view.

Fig. 5. SEM images. A) Geochus inaequalis, protarsus, the arrow indicating absence of pretarsal claw (ventral aspect). G. rufipictus: B) Head (dorso-anterior aspect), C) Enlargement of frons and dorsal surface of rostrum, D) Mesonotum, E) Left elytron. F) G. rugulosus, mesonotum.

Fig. 6. SEM images. A) Geochus rugulosus, left elytron. G. sulcatus: B) Mesonotum, C) Right elytron, D) Enlargement of elytron, showing canal openings of wax glands (arrows). G. tibialis: E) Head (dorso-anterior aspect), F) Enlargement of frons and dorsal surface of rostrum.

Fig. 7. SEM images, Geochus tibialis. A) Left antenna, showing apex of scape and funicular articles, B) Mesonotum, C) Right elytron, D) Enlargement of elytron, showing canal openings of wax glands (arrows), E) Pro- and mesothorax, lateral aspect, showing partially fused metaventrite and metepisternum, F) Enlargement of metepisternum, showing stellate setae/tentacular scales on mes- and metanepisterna.

Fig. 10. Geochus kuscheli, new species, confocal microscope images. Mouthparts: A) Labium, ventral view, B) Maxilla, ventral view, C) Left mandible, dorsal view, D) Right mandible, dorsal view. E) Dorsal view of the apicoventral portion of rostrum showing pharyngeal plate (arrow), F) Lateral view of meso- and metathorax showing reduced hind wing.

Fig. 11. Geochus inaequalis, confocal microscope images. Mouthparts: A) Labium, ventral view, B) Maxilla, ventral view, C) Left mandible, dorsal view, D) Right mandible, dorsal view. E) Ventral portion of rostrum apex with mouthparts (mandibles removed), showing pharyngeal plate (arrow), F) Pharyngeal plate showing the location of the anterior and posterior arms, and the fully sclerotized base of the plate (arrow).

Fig. 8. Geochus kuscheli, new species, male (A–C) and female (D–E) terminalia. A) Aedeagus, dorsal view, B) Aedeagus, lateral view, C) Sternites VIII (with spiculum gastrale) and IX, D) Spermatheca, E) Sternite VIII.

Fig. 9. Geochus kuscheli, new species, male (A–C) and female (D–E) terminalia, confocal microscope images. A) Aedeagus, dorsal view, B) Aedeagus, lateral view, C) Sternites VIII (with spiculum gastrale) and IX (arrow), D) Sternite VIII and spermatheca, E) Enlargement of spermatheca in D.

Fig. 13. Male terminalia, confocal microscope images. Geochus plagiatus: A) Aedeagus, dorsal view, B) Aedeagus, lateral view, C) Sternites VIII (with spiculum gastrale) and IX (arrow). G. rufipictus: D) Aedeagus, dorsal view, E) Aedeagus, lateral view, F) Sternites VIII (with spiculum gastrale) and IX (arrow).

Fig. 12. Geochus inaequalis, female terminalia, confocal microscope images. A) Sternite VIII and spermatheca, B) Enlargement of sternite VIII, C) Enlargement of spermatheca.