Tomoxia bucephala A. Costa, 1854

Naczi, Robert, Androw, Robert A. & Rosenfeld, John, 2022, Tomoxia bucephala A. Costa (Coleoptera: Mordellidae), a Palearctic tumbling flower beetle established in North America, Insecta Mundi 2022 (939), pp. 1-15 : 5

Tomoxia bucephala A. Costa, 1854

Figures 1–4 , 5A–B , 8A , 9

Diagnosis. Antenna, legs, and body uniformly very dark brown or black; elytra unstriped or with relatively short stripes that extend from base toward medial region, but do not extend beyond it; pronotum with pale pubescence along the margins and with two pale longitudinal stripes in medial region (often faint) but no additional stripes or spots.

Description. Length. Length of beetle in repose (head resting against bases of front legs), from vertex to elytral apices 5.3–6.0 mm, from vertex to apex of pygidium 6.2–7.6 mm. Ground color. Uniformly very dark brown or black, including head, antennae, elytra, venter, and legs. Antenna. Reaching nearly to base of pronotum when extended posteriorly in repose; antennomeres I–IV comprising narrowly cylindrical portion of antenna, antennomere I cylindrical, about 2× as long as wide, 1.25× as long as II; antennomere II subcylindrical, only slightly longer than wide, the shortest antennomere; antennomeres III–IV cylindrical, each 3–4× as long as wide, III about as long as IV, each nearly 2× as long as antennomere II; antennomeres V–X comprising serrate portion of antenna, each antennomere subtriangular with distal portion the widest, antennomere V about 0.75–1× as long as IV, antennomere VI as long as V, antennomeres VI–X successively and gradually diminishing in length and width; antennomere XI 2.2× as long as wide, about as long as antennomere IV, antennomere body narrowly triangular, one margin projecting distally as finger-like lobe with obtuse apex, lobe about 0.25× as long as antennomere XI. Eye. Reaching posteriolateral margin of head, finely hairy, hairs moderately dense. Pronotum. Transverse, wider than elytra, widest at about middle; lateral margins evenly and gradually curved from base to apex, basal angles obtuse, basal margin with truncate lobe occupying central third, basal margin gradually anteriorly curved laterad to basal lobe; lateral margins covered with pale, golden or gray hairs; with median pair of golden or gray stripes running from base to apex, stripes often faint, space between stripes covered by dark brown hairs, portions laterad to each stripe covered with golden or gray hairs to a varying extent and a dark brown patch of varying size and shape, sometimes pale hairs nearly fill this area and sometimes dark brown hairs fill all but the pale stripes at margins. Scutellum. Transverse, 1.5–1.8× as wide as long, posterior margin shallowly and broadly emarginate, entire surface covered with golden and/or gray hairs. Elytra. Each 3.9–4.4 × 0.9–1.2 mm, both elytra 2.0– 2.5 mm wide at base; covered with dark brown hairs, except for the following areas covered with pale brown or pale gray or whitish hairs: along suture from base to a point 85–95% of elytral length, most of area in distal 15–20% of elytra, one suborbicular spot in medial region of each elytron between suture and lateral margin that often merges with pale hairs along suture, within an area at base just mesad to humeri that extends mesally to suture and extends obliquely from base toward suture in medial area of elytra, this basal pale area sometimes with 1–2 dark brown oblique stripes within it that parallel the oblique margin of the pale basal area; apices evenly and widely rounded from margins to suture. Pygidium. Widely conical, dorsally covered with golden or gray hairs in basal 35–40%, remaining portion covered with very dark brown hairs; apically truncate, microctenidiate at apical margin; 1.8–2.5× as long as hypopygium. Venter. Uniformly covered with golden or grayish hairs. Mouthparts. Terminal maxillary palpomere triangular, scalene, lateral side the longest, mesal side the shortest, apical side with sulcus spanning its length. Legs. Pro-, meso-, and metatibiae 0.9× as long as corresponding pro-, meso-, and metafemora; protibia 1.1–1.3× as long as protarsus, mesotibia 0.8–0.9× as long as mesotarsus, metatibia 0.6–0.7× as long as metatarsus; first metatarsomere 0.7–0.8× as long as metatibia; metatibia with apical ctenidium spanning tibial width and closely adjacent subapical ctenidium spanning about 0.25 of tibial width, metatibia with fine dorsal ridge spanning nearly entire tibial length, first metatarsomere with apical ctenidium spanning its width, first metatarsomere with fine dorsal ridge spanning nearly its entire length; metatibial apical spurs very dark brown, outer 0.5× as long as inner; claws toothed, with 3–4 teeth per claw, each tooth 0.3–0.5× as long as adjacent untoothed portion of claw at base of teeth.

Figures

Figure 1. Tomoxia bucephala, aspect of living beetle, Allegheny County, Pennsylvania, U.S.A. A. Dorsal view. B. Dorsolateral view. C. Ventral view. Scale bars for all images = 1.0 mm. See text for complete voucher specimen collection data.

Figure 2. Tomoxia bucephala, aspect of museum specimen, Essex County, New Jersey, U.S.A. A. Dorsal view. B. Dorsolateral view. C. Lateral view. Scale bars for all images = 1.0 mm. See text for complete voucher specimen collection data.

Figure 3. Tomoxia bucephala, aspect of museum specimen, Union County, New Jersey, U.S.A. A. Dorsal view. B. Dorsolateral view. C. Lateral view. Scale bars for all images = 1.0 mm. See text for complete voucher specimen collection data.

Figure 4. Tomoxia bucephala details of museum specimen, Essex County, New Jersey, U.S.A. A. Lateral view of portion of hind leg, with “a” indicating dorsal tibial ridge and “b” indicating dorsal ridge on first tarsomere. B. Dorsal view of distal portion of mesotibia and mesotarsus. Scale bars for all images = 0.5 mm. See text for complete voucher specimen collection data.

Figure 5. Pronota and adjacent portions of heads and elytra of Tomoxia species. A. T. bucephala, Essex County, New Jersey. B. T. bucephala, Union County, New Jersey. C. T. inclusa, Lamar County, Texas. D. T. lineella, Rockbridge County, Virginia. Scale bars for all images = 1.0 mm. Voucher specimen collection data: A—see text; B—see text; C—Texas. Lamar Co.: Camp Maxey National Guard, Powderly, 3.5 km S, 16−20 Jun 2009, J.C. Abbott (UTIC); D—Virginia. Rockbridge Co.: 0.7 km N of Fairfield, 21 Jun−14 Jul 2017, D. Heltzel, BSF# 74567 (CMNH).

Figure 8. Antennae of Tomoxia species. A. T. bucephala, Essex County, New Jersey. B. T. inclusa, Lamar County, Texas. C. T. lineella, Bronx County, New York. Scale bars for all images = 0.5 mm. Voucher specimen collection data: A—see text; B—as for Fig. 5C; C. New York. Bronx Co.: New York Botanical Garden Forest, 16−25 July 2012, E. Rivera and R. Naczi (RNC).

Figure 9. Map of known occurrences of Tomoxia bucephala in North America. Areas of heavier shading indicate metropolitan regions of New York City and Pittsburgh.