Paxillobitoma Lord and Ivie, 2016

Lord, Nathan P. & Ivie, Michael A., 2016, Several New Genera and Species of New World Synchitini (Coleoptera: Zopheridae: Colydiinae), The Coleopterists Bulletin 70 (4), pp. 715-753 : 715-753

Paxillobitoma Lord and Ivie , new genus ( Figs. 3 , 18 , 21 )

Type Species. Paxillobitoma clinei Lord and Ivie , new species.

Etymology. From the Latin “Paxillus” meaning “peg” as a modifier of “ Bitoma ,” a common and morphologically variable genus in Synchitini . This name refers to the sharp temple behind the eye and general similarities with the genus Bitoma Herbst, 1793 . Feminine.

Diagnosis. Paxillobitoma superficially resembles the genera Bitoma and Paha Dajoz, 1984 . Paxillobitoma can be distinguished from these genera by the distinctive shape of the 1-segmented antennal club, long antennal grooves that extend to or beyond the posterior margin of the eye, distinct, sharply acute temples projecting past the lateral margin of eye, and excavations in the antero-lateral corners of the prothorax for reception of the antennal club.

Description. Size small (TL = 2.4 mm) body elongate, subparallel, flattened (TL/EW = 2.3); dark to light brown. Dorsal surface simple, with few longitudinal carinae on pronotal disc and elytra; vestiture consisting of short, curved setae at apex of carinae and adjacent to elytral punctures. Ventral surface reticulo-punctate; vestiture consisting of short, sparse, curved setae. Habitus as in Fig. 18 . Head: Subquadrate (HW = 0.4 mm), broadest at eyes, with distinct, sharply acute temples, lateral apex of temple extends past lateral margin of eye, not constricted behind eyes, apical margin sinuate, apico-lateral margins slightly angulate ( Fig. 3a ). Transverse groove at base of eye; with paired, apico-laterally diverging sulci continuing nearly to margin, less distinct apically, connected basally by slight median depression, grooves result in swollen antero-medial and posterio-medial areas, and slightly raised lateral portion (frontal ridge) anteriad eyes. Head with distinct ridge dorsad eye (best seen in lateral view). Dorsal surface with small, round to ovoid granules, variable in size, each bearing short, thickened seta. Eyes entire, convex, facets large, interfacetal setae absent. Ventral surface: antennal groove distinct, long, curving around posterior margin of eye. Gena slightly inflexed basad mentum. Subgenal brace weakly developed, truncate anteriorly, extending past antennal pedicel (when antenna retracted into antennal groove). Antennae: Shorter than total length of head, not extending past junction of head and pronotum; 10-segmented, ending in an abrupt, 1-segmented club ( Fig. 3d ). Scape asymmetrical, constricted and then abruptly expanded at base to form an angulate, cupule-like socket, apical portion of scape swollen, nearly as wide as long; pedicel subspherical, slightly asymmetrical, about as large as apical portion of scape; antennomere 3 narrow basally and slightly and gradually expanding apically, about as long as 4+5; antennomeres 4–9 short, increasingly shorter and wider; antennomere 10 larger, forming an abrupt club, greatly expanding anteriorly, truncate at apex, with rounded setose apical field. Antennomeres 3–9 each with ring of fine setae, setae about as long as segment; antennomere 10 with few intermittent setae, apical margin fringed with short, dense setae, apical setose field with short, dense pubescence and few longer setae. Mouthparts: Labrum subquadrate, anterior margin arcuate, fringed with few sparse setae. Mandibles symmetrical, with distinct mola and

24) Species in Costa Rica and Panama.

membranous prostheca; mandibular apex bidentate, with third, broader subapical tooth ( Fig. 3f ). Maxillary palpi 4-segmented, terminal palpomere conical ( Fig. 3c ); galea and lacinia of normal form, bearing numerous stout setae apically; lacinia with single, curved spine. Mentum subquadrate, truncate apically ( Fig. 3b ); ligula transverse, antero-lateral angles somewhat swollen and expanded, anterior margin slightly concave, fringed with row of short, dense setae; labial palpi 3-segmented, terminal palpomere conical to slightly fusiform, labial palpi inserted ventrally. Prothorax: Pronotum subquadrate, parallel-sided (PW = 0.8 mm, PL = 0.7 mm, PL/PW = 0.8). Lateral margins of pronotum straight, slightly explanate, granulate ( Fig. 3h ); anterior angles distinct, rounded, not reaching level of anterior margin. Anterior margin raised, sinuate, arcuate in medial portion, with beaded margin, depressed/notched/excavated just inside of anterior angles. Anterior margin without fringe of setae. Posterior margin slightly sinuate to straight, fringed with row of short, fine setae, directed posterior-medially; posterior angles distinct, at right angles. Pronotal disc with 2 pairs of subtle carinae, medial pair diverging antero-laterally from base until anterior ¼, then carinae converge antero-medially until ending at anterior margin; sublateral carinae converge medio-laterally from base until about middle of pronotum, then carinae diverge anterolaterally until ending at anterior margin; central portion between median pair of carinae slightly depressed. Surface granulose, covered with subequal round to ovoid granules, each bearing short seta; carinae crested with short, curved setae. Anterior inner angles of prosternum/hypomeron excavated to receive antennal club. Prosternal process nearly parallel-sided, slightly narrowing anteriorly, slightly expanded near apex, apex slightly trilobate; prosternal process slightly raised; procoxal cavities open externally, procoxae countersunk, prosternal process extending ventrad and concealing inner ¼ of procoxae from view. Procoxae round, externally separated by about width of visible portion of procoxa, internally very narrowly separated. Mesothorax: Scutellum well-developed, visible, oval. Mesoventrite: Apical margin of mesoventrite straight to slightly convex. Mesoventral process slightly narrowed apically, apex strongly notched medially ( Fig. 3i ), articulating with well-developed “nipple” at apex of metaventral process, forming locking mechanism. Mesocoxal cavities broadly closed, mesocoxal separation moderate, about ⅓ width of coxal diameter (visible coxa, not accounting for countersunk portion). Elytra: Elongate, parallel-sided, widest at apical ⅓ (EL = 1.7 mm, EW = 1.0 mm, EL/EW = 1.6). Humeral angles weakly produced. Anterior margin evenly concave, with fringe of sparse, thin, internally directed setae; lateral margins not explanate, weakly granulate, margined by row of short, curved setae. Apex rounded. Surface with subtle carinae on interstrial intervals 1, 3, 5, 7, and 9; sutural carina (interval 1) raised, beaded, diverging anterolaterally to form scutellary striole; carina on interval 3 extends from elytral base and becomes confluent with carina on interval 9 near apex, which then extends to apical margin; carina 9 ends just short of elytral base; carinae on intervals 5 and 7 extend from elytral base and become confluent near apex, basal to junction of carinae on intervals 3 and 9. With 9 puncture rows. Surface seriotuberculate, with evenly spaced, subequal round to ovoid granules, each bearing a short seta. Epipleuron present, weakly defined, gradually narrowing, but reaching elytral apex. Metaventrite: Longer than abdominal ventrite I. Discrimen present, short, strongly impressed between metacoxae. Metacoxae transverse, narrowly separated ( Fig. 3i ). Metendosternite as in Fig. 3g . Furca narrow, tapering posteriorly; laminae short, rounded; lateral furcal arms long, narrowing apically; anterior tendons narrowly separated; metafurcal ventral flange present, not strongly projecting ventrally. Abdomen: Ventrite I slightly longer than II (but not longer than II+III, length does not include intercoxal process) ( Fig. 3j ). Abdominal ventrites II–V gradually shorter, freely articulated, not connate. Intercoxal process narrow, acute. Abdominal ventrite V lacking groove, but with apical margin slightly thickened and bordered. Ventrites with short, curved setae, setation of ventrite V similar to ventrites I–IV. Legs: Trochanters present, visible, trochantero-femoral attachment strongly oblique ( Fig. 3e ). Femora simple, rugose, anterior margin slightly sinuate, posterior margin slightly arcuate, femora widest at middle; with sparse, short setae. Tibiae simple, very slightly expanded apically, external margin microtuberculate, each tubercle bearing a short seta. Tibial apex with paired, extremely short spines ventrally (difficult to see in uncleared specimens). Tarsomere 1 slightly longer than 2 (but not as long as 2+3), slightly narrowed at base, with longer, denser setation than remaining tarsomeres; tarsomeres 2–3 subequal in size; tarsomere 4 elongate, longer than 1–3 combined, slightly expanded apically, setation sparse; tarsal claws simple. Metathoracic wing: Fully developed. Aedeagus: Elongate, parallel-sided ( Fig. 3k ), extending nearly entire length of abdomen in situ; curved dorsally ( Fig. 3l ), cucujiform, tegmen lying dorsad medial lobe; anteroventral edge of segment IX with spiculum gastrale. Ovipositor: Terminalia with long, moderately thick spiculum ventrale, clubbed proximally. Ovipositor elongate ( Fig. 3m ), with weakly sclerotized segments. Tergite IX completely divided into 2 lateral paraprocts. Paraproct with long baculus, about 1.25X as long as gonocoxite. Tergite X weakly sclerotized, situated between paraprocts. Proximal and distal lobes of gonocoxite weakly separated; proximal lobe with weakly indicated transverse basal baculi; basal lobe short, cylindrical, more wellsclerotized than proximal lobe; with well-developed, palpiform gonostylus attached apically; gonostylus with few setae at apex. Female reproductive tract: Not examined.

Distribution. Known from Panama in Central America and French Guiana, Brazil, and Bolivia in South America.

Comments. The type series of P. clinei consists of eight specimens collected in French Guiana. There are an additional four specimens from Brazil, one from Bolivia, and one from Panama. Examination of this non-type material did not reveal any distinct morphological variation from the type series, but due to the limited number of specimens available for study, no dissections were performed. Therefore , we elect to describe this monotypic genus from the French Guianese material alone. It is possible the Panamanian , Brazilian and Bolivian members may prove to be distinct species, but until more material can be obtained, we refrain from describing additional taxa .

Figures

Fig. 3. Paxillobitoma clinei. a) Head, ventral view, b) Labium, ventral view, c) Maxilla, ventral view, d) Antenna, e) Fore leg, f) Mandible, ventral view, g) Metendosternite, ventral view, h) Prothorax, ventral view, i) Pterothorax, ventral view, j) Abdominal ventrites I–V, ventral view, k) Aedeagus, dorsal view, l) Aedeagus, lateral view, m) Ovipositor, dorsal view.

Figs. 17–20. Synchitine Colydiinae, dorsal habitus. 17) Helonoton tripartum, holotype (CMNC); 18) Paxillobitoma clinei, holotype (FSCA); 19) Rapthius peruvianus, paratype (NHMW); 20) Slipinskius chilensis (AMNH). Scale bars = 1 mm.

Figs. 21–22. Distribution maps. 21) Globotrichus harti in Costa Rica and Panama (Bolivian and Brazilian specimens not shown, see text), Paxillobitoma clinei in French Guiana (Bolivian, Brazilian, and Panamanian specimens not shown, see text), and Rapthius peruvianus in Peru; 22) Slipinskius chilensis in Chile.