Helonoton tripartum 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

Helonoton tripartum Lord and Ivie , new species ( Figs. 17 , 23 )

Diagnosis. Helonoton tripartum most closely resembles H. bituberculatum , but differs in the 3-segmented antennal club, head with distinct temples, head abruptly constricted behind the temples, scutellary striole apparent, central ridge on pronotal disc evenly raised throughout, anterior lobes of lateral pronotal margin less strongly produced, basal ⅔ of lateral pronotal margin gradually narrowed basally, with a small denticle, with only a single pair of mid-lateral pronotal tubercles, and elytral tubercles densely setose, approaching hirsute.

Description. Size small (TL = 2.6 mm), body convex-oval (TL/EW = 1.8), subparallel; unicolorous, light brown; habitus as in Fig. 17 . Head: Transverse (HW = 0.6 mm), with distinct temples, abruptly constricted behind temples. Antennae: 11-segmented, ending in an abrupt, 3-segmented club; antennomeres 9–11 forming distinct club, antennomere 10 transverse, trapezoidal to slightly asymmetrical, narrowest at base; antennomere 11 truncate at base, transverse, rounded apically. Prothorax: Pronotum subquadrate (PW = 1.1 mm, PL = 0.8 mm, PL/PW = 0.8), widest at apical ⅓, narrowest at base. Lateral margins of pronotum sinuate, widening apically, anterior ⅓ produced into moderate arcuate lobe, posterior ⅔ of lateral pronotal margin with small lobe or denticle; anterior angles distinct, slightly projecting forward to about level of anterior margin; posterior angles present, small. Pronotal disc with complex patterns of ridges and depressed areas; central portion with strongly depressed area, bordered laterally by sinuate ridge, ridge equally raised throughout; central portion bordered anteriorly by paired, short, parallel ridges that become confluent with anterior margin and bordered basally by paired, baso-laterally directed ridges that end before posterior margin, creating sutriangular baso-medial depression; single pair of ovoid, mid-lateral tubercles present between lateral pronotal margin and basal half of central sinuate tuberculate ridge, slightly posterior to pronotal midline. Procoxal cavities open externally. Mesothorax: scutellum well-developed, visible, oval. Elytra: Elongate, parallel-sided, widest at middle (EL = 1.8 mm, EW = 1.4 mm, EL/EW = 1.3). Surface with series of well-defined tubercles and shallow carinae/ridges bearing dense setae, appearing hirsute. Sutural stria raised, beaded, diverging antero-laterally to form subtle scutellary striole. Each elytral base with a swollen tubercle at base of elytral interstrial interval 3, and an irregular swollen tubercle at humeral angle. Interval 9 without well-defined carina or tubercles. Remaining tubercles on middle portion of elytra large, elongateoval, subequal in size. Carinae present on elytral declivity, short, not extending nearly to apex. Epipleuron present, well-defined basally, incomplete to apex, ending at junction of abdominal ventrites IV and V. Metaventrite: Slightly shorter than or about as long as length of abdominal ventrite I; with paired sinuate grooves directly posteriad and bordering mesocoxae, also with paired, slightly curved grooves directly anteriad and bordering metacoxae. Discrimen short, extending only to basal ⅓ of metaventrite, strongly impressed between and anteriad metacoxae. Metacoxae transverse, narrowly separated. Metendosternite of apterous form (see genusgroup description). Abdomen: Intercoxal process of abdominal ventrite I triangular, apex broadly rounded, not acute. Only known from single female, but it is expected males will exhibit similar dimorphism in ventrites III and IV as found in other species. Metathoracic wing: Reduced.

Distribution. Mexico ( Fig. 23 ).

Biology. The holotype was collected by berlese of wet leaf/log litter in oak/pine/fir forest.

Etymology. Named after the 3-segmented antennal club, a diagnostic character for this species.

Type Material. 1 specimen. Holotype, female: (pointed, partially dissected, genitalia and abdomen in glycerine in genitalia vial pinned underneath specimen, CMNC): MEXICO: Guerrero, 10.3km.; S.W. Filo de Caballo , 2700m; 92-002, 13.VII.1992, R.S.; Anderson,oak/pine/fir Forest; (wet),leaf/log litt. Berlese [abdomen and genitalia dissected by NPL, in glycerine in genitalia vial pinned beneath specimen]

Figures

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. 23–24. Distribution maps of Helonoton species. 23) Species in Mexico, Guatemala, El Salvador, and Honduras;