Anthonaeus, HORN, 1879

Cline, Andrew R. & Audisio, Paolo, 2010, Revision of the New World Short-Winged Flower Beetles (Coleoptera: Kateretidae). Part I. Generic Review and Revision of Anthonaeus Horn, 1879, The Coleopterists Bulletin 64 (3), pp. 173-186 : 176-179

REVISION OF ANTHONAEUS HORN, 1879

Anthonaeus Horn 1879: 273 ; gender - masculine Type Species: Colastus agavensis Crotch 1874: 76

(by monotypy)

Adult Diagnosis. D i ff e r s f r om a l l o t h e r Kateretidae by the following combination of characters: body dorso-ventrally compressed; mandible with prominent subapical tooth; prosternum elongate,>1.5× the length of the prosternal process.

Adult Description. Body overall dorso-ventrally compressed; elongate, widest near visible abdominal tergite 1; body densely punctate and finely setose; setae light brown to golden in color; pronotum and elytra fimbriate.

Head broadly triangular, wider than long, narrower than pronotum; vertex transverse; frontoclypeal region with transverse, shallow sulcus; occipital line well developed medially. Temples short and posteriorly arcuate. Eyes well developed, moderately protruding laterally, finely faceted, interfacetal setae absent. Clypeus with anterior margin moderately to deeply concave; lateral anterior angles acute. Labrum transverse, anterior margin concave with visible portion appearing moderately bilobed, antero-lateral lobes broadly rounded, strongly setose on anterior margin ( Fig. 2A ). Mandibles well developed; broadly widened basally; apex acuminate; distinct subapical tooth present; lateral setigerous furrow present with elongate setae; ventro-medial articulation dicondylic; mola not well developed with faint, short, oblique lines; prostheca indistinct ( Fig. 2C ). Maxilla with galea and lacinia elongate and narrow; cardo and stipes well developed, subequal in length; stipes with lateral margin lunate; galea with apical third densely setose with short and elongate setae, apex moderately hook-shaped, lacinia thinner than galea and subequal in length, palp 4-segmented with terminal segment conical and equal in length to segments 1–3 combined ( Fig. 2D ). Mentum transverse, well developed, clearly demarcated from submentum and gula; anterior margin with deep concavity in medial third ( Fig. 2B ). Labium with 3-segmented palp, palpi well separated at base by width of basal segment, terminal segment obovate and slightly longer than segment 2 ( Fig. 2B ). Antennal grooves absent on ventral side of head. Antennae 11-segmented; scape moderately enlarged, 1.8–2.0× length of pedicel; segments 2–8 similar in shape, becoming dilated apically; segments 9–11 forming a loose club, 9–10 similar in size and shape, segment 11 subequal to 9–10 combined, apex acuminate and appearing appendiculate.

Pronotum moderately transverse, narrower than bases of elytra, finely fimbriate, anterior angles broadly rounded but distinct, posterior angles indistinct. Prosternum relatively elongate, ∼ 1.5× longer than prosternal process, demarcated from proepisternal by well defined suture. Prosternal process narrow, parallel-sided, extending slightly beyond posterior margin of procoxal cavities, not expanded laterally behind procoxal cavities, apex truncate to broadly evenly convex, in lateral view with posterior margin rounded with no vertical face. Procoxal cavities externally narrowly open. Mesonotum with scutellum visible, large, hemispherical with apex rounded. Mesosternum large and conspicuous, flattened, at same level as metaventrite, posterior mesosternal process twice as wide as prosternal process and extending to midway between the mesocoxal cavities with truncate posterior margin. Metaventrite transverse, subequal to 2× length of mesosternum; discrimen present along posterior two-thirds of midline only, not apparent in anterior third. Metendosternite of cucujoidhylecoetoid type, anterior tendons arising medially from furca, sclerotized lateral arms of furca welldeveloped with blunt apices, lateral parts of ventral process of furca obliquely oriented to base of furca, stalk of furca short and lyriform with heavily sclerotized ventral median flange, base of furca wide and broadly attached to metaventrite ( Fig. 3 ).

Elytra abbreviated, not covering last two visible abdominal tergites; epipleuron broad in basal half, then dramatically narrowing in apical half; lateral margins not explanate; apical margins broadly evenly rounded; humeral angles vaguely indicated, not prominent; sutural striae visible; pubescence fine and short, fimbriate. Visible abdominal ventrite 1 projecting between metacoxae, with broadly rounded apex. All ventrites with fimbriate margins. Male pygidium with deeply concave posterior margin exposing “anal sclerite”.

Legs normal, i.e. no sexual dimorphism apparent, with all femora shallowly caniculate for reception of tibiae; widest near middle. Tibiae with paired unequal apical spurs. Tarsi 5-5-5; tarsomere 4 small and situated between weekly bilobed tarsomere 3, tarsomeres 1–3 weakly bilobed with dense setose pad; tarsomere 5 moderately elongate, equal to length of tarsomeres 1–2 combined; claws simple.

Male genitalia with tegminal parameres not fused to each other or phallobase, symmetrical. Median lobe (penis) asymmetrical. Female genitalia with coxites slightly diverging apically and possessing short apical lateral styli.

Variation. Some specimens may possess lighter colored elytra than the body, or the entire body may appear uniformly colored.

Larval Diagnosis. Due to the scarce knowledge of New World Kateretidae larval forms, in particular Neotropical taxa, there is great difficulty in ascertaining the true affinities of Anthonaeus solely based on immature forms. However, original observations based on Nearctic taxa, including an upcoming description of Amartus larvae, suggest that a relationship to Amartus can be supported by the following shared characters: frontal sutures distant at base; epicranial stem absent; sensory appendage on antennal segment three-fourths length of terminal segment; spiracles annular-biforous; inner margin of mandible with three or more well developed subapical teeth; mandibular mola with one or more tooth-like projections; and tarsi without adhesive lobe. Inclusion of Neotropical genera such as Neobrachypterus and Cercometes would greatly advance our understanding of this genus and New World taxa in general; however, immatures from these genera remain unknown.

Mature Larval Description (3 rd Instar).

Length 3.5–5.5 mm, width 0.8–1.1 mm across abdominal segment 3. Body elongate, subparallel, moderately convex, widest near A3, urogomphi and pregomphi absent. Overall, body almost circular in cross-section. Only head well sclerotized, T1 with faint rugosities anteriorly and laterally, legs moderately well sclerotized, remainder of body integument pale whitish/cream colored and overall lightly to unpigmented with some faint scale-like sculpturing present. Dorsal body setae short, simple, scattered, and erect, not borne on short tubercles ( Figs. 4A and 4B ).

Head ( Fig. 5A ). Prognathous, narrower than T1, not concealed by prothorax, surface mostly smooth with faint rugose areas antero-medially. Dorsal posterior margin of capsule deeply indentate medially. Clypeus bearing 2 pairs of macrosetae, each pair near antero-lateral angles, other microsetae may be present; clypeofrontal protuberances absent. Frontoclypeal suture distinct. Epicranial stem absent, frontal sutures “V-shaped” but separate from each other. Median endocarina absent. Four stemmata present on each side of head, but weakly developed. Antenna 3-segmented with relative antennomeral lengths from base to apex 1.0:1.2:0.8. Antennal base broad, pseudorectangular to somewhat globular. Segment 1 simple, somewhat rounded laterally, asetose. Segment 2 transverse, 2–3 macrosetae present apically, and with a sensory appendage 0.75× length of segment 3. Segment 3 cylindrical, smaller than either of preceding 2 segments, bearing 1 long apical

A) Ventral view, B) Lateral view. macroseta.Labrum free, moderately large, transverse. Hypostomal rods long, diverging posteriorly. Mandibles symmetrical, apical tooth with grooved dorsal cutting margin; typically 3 subapical teeth present along medial margin; prostheca absent; mola with tooth-like projection and granular grinding surface; base of mandible broadly widened with strongly dicondylic articulation ( Fig. 5B ). Ventral mouthparts retracted. Maxilla with bluntly rounded undeveloped asetose mala. Maxillary palp 3-segmented, segments 1 and 2 subequal, segment 3 slightly smaller than 1 or 2 and possessing terminal sensory setae. Mentum/ submentum moderately transverse; ligula not well developed. Labial palpi simple, short, widely separated, 1-segmented with terminal seta.

Prothorax narrower and longer than meso- and metathorax, and with more distinct granular surface sculpturing. Length ratio of prothorax/mesothorax/ metathorax 1.5:1.0:1.0. Meso- and metathorax equal in length, with metathorax somewhat wider. All thoracic terga with widely scattered short, elongate macrosetae. Legs well developed, widely separated, 2 tarsungular setae present. Ten abdominal segments total ( Figs. 5 C-E), moderately lobed laterally. Abdominal segments 1–8 similar in shape; A9-10 smaller and more globular in shape; A10 broadly with apical margin broadly evenly convex. Spiracles annular-biforous, not borne on tubercles. Pregomphi and urogomphi absent. Anal opening “Y-shaped”, with superior slits appearing lyriform, not angulate.

Notes. Horn’ s original description (1879: 273), albeit short and somewhat generalized, provided an adequate differentiation of Anthonaeus from the rest of the New World Kateretidae fauna. However, the first robust assessment and thorough description of the genus was completed by Parsons (1943) in his treatment of the entire Nearctic Nitidulidae and Kateretidae (= Parsons’ Cateretinae ).

Figures

Fig. 2. Mouthparts of Anthonaeus agavensis. A) Labrum, dorsal view, B) Mentum and labium, ventral view, C) Left mandible, dorsal view, D) Left maxilla, dorsal view.

Fig. 3. Metendosternite of Anthonaeus agavensis. A – lateral arms of furca, F – ventral flange of furca, ST – stalk of furca, T – anterior tendons of furca.

Fig. 4. SEM images of Anthonaeus agavensis 3rd instar.

Fig. 5. Larval features of Anthonaeus agavensis 3rd instar. A) Ventral view of head, B) Ventral view of right mandible, C) Dorsal view of left-hand portion of abdominal tergite 5, D) Lateral view of abdominal segments 9-10, E) Dorsal view of abdominal tergite 9.