Rapthius 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

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https://doi.org/ 10.1649/0010-065X-70.4.715

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scientific name

Rapthius Lord and Ivie

gen. nov.

Rapthius Lord and Ivie , new genus ( Figs. 19 View Figs , 21 View Figs )

Type Species. Tarphius peruvianus Franz, 1969 .

Etymology. Anagram of Tarphius Erichson, 1845 , the original genus in which this species was described. Masculine.

Diagnosis. Rapthius shares the elongate first tarsomere concealing the smaller second tarsomere with Monoedus Horn, 1882 , but can be easily distinguished by the much narrower first tarsomere, 10-segmented antennae (as opposed to 9-segmented in Monoedus ), antennal club of a different shape, body more oval and dorsally convex ( Fig. 19 View Figs ), and vestiture consisting of long, thin, erect setae. Rapthius superficially resembles the New Zealand genus Heterargus Sharp, 1886 and can be distinguished from this and all other genera by the combination of 3-segmented tarsi, a 1-segmented antennal club, and the presence of labial palpi.

Description. Size small (TL = 2.1 mm), body convex-oval (TL/EW = 1.2), rounded; golden to light brown; habitus as in Fig. 19 View Figs . Dorsal surface granulose; vestiture consisting of long, erect, hairlike setae. Ventral surface granulose; vestiture consisting of short, sparse, hair-like golden setae. Head: Subquadrate (HW = 0.5 mm), broadest at eyes, without temples, head not abruptly constricted behind eyes, apical margin arcuate, apico-lateral margins swollen, raised anteriad eyes. Dorsal surface with large, round to ovoid granules, each bearing a thin, short seta. Frontoclypeal suture absent. Anterior margin of clypeus fringed with long, thin setae. Eyes small, reduced to a few large facets, interfacetal setae absent. Ventral surface: antennal groove absent. Subgenal brace weakly developed. Antennae: Moderately short, extending to middle of pronotum. Antennae 10-segmented, ending in an abrupt, 1-segmented club. Scape barrel-shaped, slightly longer than wide; pedicel abruptly narrowed at base, slightly longer than scape; antennomere 3 narrow basally and slightly and gradually expanding apically, longer than 4 but not as long as 4+5; antennomeres 4–9 short, irregular, nearly spherical, subtly increasing in size; antennomere 10 enlarged, ovoid, slightly asymmetrical, longer than wide, forming an abrupt club, apex with constriction (apparent fusion with antennomere 11), antennomere 10 slightly shorter than 7–9 combined. Antennomeres 2–9 each with a ring of fine setae, setae about as long as segment; antennomere 10 with intermittent thin, long setae and short, dense pubescence at apex. Mouthparts: Labrum with anterior margin evenly curved, fringed with row of long, thin setae. Mandible bidentate; maxillary palpi 4-segmented, terminal palpomere fusiform; galea and lacinia of normal form; mentum subquadrate, anterior margin concave medially; labial palpi 3-segmented, terminal palpomere fusiform, widest near base; labial palpi inserted ventrally. Prothorax: Pronotum transverse, widest at middle (PW = 1.1 mm, PL = 0.7 mm, PL/PW = 0.7), convex (lateral margin on lower plane). Lateral pronotal margins slightly explanate, granulose; anterior angles distinct, angulate, slightly projecting, reaching near basal margin of eye. Anterior margin evenly arcuate, depressed/notched/excavated just inside of anterior angles. Posterior margin evenly arcuate, fringed with row of short, fine setae, directed posteriormedially; posterior angles indistinct, acute, projecting baso-laterally. Pronotal disc convex, granulose (granules smaller than those on elytra), covered with subequal round to ovoid granules, granules distinctly separate from one another, each bearing a moderately long, thin, erect seta. Prosternum/hypomeron without excavations forming antennal cavities. Prosternum rugose, with distinctly separated, irregular granules on the hypomeron. Anterior margin of prosternum fringed with row of short, fine setae, directed anteriorly. Prosternal process nearly parallel-sided, slightly narrowing anteriorly, slightly expanded near apex, apex with slight emargination medially; 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 greater than width of visible portion of procoxa, internally separated by less than ½ coxal diameter. Hypomeral extensions angulate, posterior margin fringed with row of short, fine setae, directed posterio-medially. Mesothorax: Scutellum apparently absent. Mesoventrite: Short, tightly fitting with metaventrite. Rugose with random pits/ fovea. Apical margin straight to slightly sinuate. Mesoventral process slightly narrowed apically. Mesocoxal cavities broadly closed, mesocoxal separation moderate, about ½ width of coxal diameter (visible coxa, not accounting for countersunk portion). Elytra: Oval, widest at middle (EL = 1.4 mm, EW = 1.1 mm, EL/EW = 1.2), narrowing gradually to rounded apex. Humeral angles not distinct, rounded, with few granules at outer margin. Anterior margin straight, slightly concave at middle; lateral margins not explanate. Scutellary striole absent; With 7 puncture rows becoming confused around elytral tubercles. Surface with slightly raised granules/tubercles between punctures (granules larger than those on pronotum), each granule bearing a moderately long, thin, erect seta near elytral puncture. Epipleuron present, weakly defined, gradually narrows, ending near junction of abdominal ventrites IV and V. Metaventrite: Short, about as long as or slightly longer than abdominal ventrite I; rugose with random pits/fovea. Without obvious setae. Discrimen absent, area between metacoxae not impressed. Metacoxae oval, moderately separated, separation about ½ of coxal diameter. Metanepisternum apparently fused to metaventrite. Metacoxal cavities closed. Metendosternite not examined. Abdomen: Ventrites I–III connate; ventrite I slightly shorter than II; intercoxal process nearly parallel-sided, apex broadly rounded. Abdominal ventrite II slightly longer than other ventrites; ventrites III–IV subequal in length. Abdominal ventrite V slightly shorter than III+IV, rounded at apex, lacking preapical groove, but with slightly swollen apical border. Ventrites I–II with large granules, ventrites III with few large granules near lateral margins; ventrites IV–V lacking granules. Legs: Trochanters present, visible, trochanterofemoral attachment strongly oblique. Femora simple, narrowest near base, expanding at basal ⅓, with sparse, short setae. Tibiae simple, with slight excavation at distal end on dorsal surface and sparse, short setae. Tibial apex ringed with short, stout setae. Tarsomere 1 swollen, elongate-oval, concealing tarsomere 2, slightly wider than tarsomeres 2 and 3; tarsomere 2 small, barely visible; tarsomere 3 longer than 2; setation on ventral surface of tarsomeres 1–3 moderately long (setae about as long as tarsomere 2); tarsomere 4 elongate, slightly longer than 1– 3 combined, slightly expanded apically, setation sparse; tarsal claws simple. Metathoracic wing: Not examined, but presumed absent. Aedeagus: Not examined. Ovipositor: Not examined.

Distribution. This genus is only known from the type locality in Peru.

Biology. Nothing is known about the habits of the only known species in this genus. It is presumed to be a soil-dwelling species, and therefore likely a detritovore or fungivore like many other members of the Synchitini . As this is presumably a flightless species, it is assumed nearly all specimens will be taken by litter sifting and Berlese extraction.











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