Dasyus LePeletier & Audinet-Serville 1828
Creators: name: Fuhrmann, Juares
Publisher: name: Zenodo
Year: 2019
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Melolonthidae
Dasyus

description: Dasyus LePeletier & Audinet-Serville, 1828
Dasyus LePeletier & Audinet-Serville, 1828: 369; Latreille 1829: 562; Guérin-Méneville 1830: 85, 90; Erichson 1845: 655; Desmarest 1851: 68, 131; Rühl 1888: 74, 1889: 59.
Type species. Dasyus collaris LePeletier & Audinet-Serville, 1828 (designation: monotypy).
Diagnosis. Pronotum covered with thin setae (Fig. 24), prosternum with an anterior longitudinal carina (Fig. 40); limit of mesoscutum–scutellum angulate (Figs. 46, 51–52); protibia with two outer teeth and a spur (Fig. 41); medial area of mesotibia and metatibia as wide as apex (Figs. 42–44); protarsal claw bifid (Fig. 41), mesotarsal and metatarsal claws simple (Figs. 42–44); ventrite VI of males with a concavity (Figs. 25–26).
Description. Body (Fig. 24) length: 7.2–12.8 mm, greatest width at half of elytra: 3.8–5.8 mm; dorsal surface shiny and with hair-like setae. Sexual dimorphism evident, females slightly larger than males, ventrite VI of males with a concavity (Figs. 25–26) and abdominal venter of females convex. Head with small eyes in dorsal view; epistomal suture slightly sinuous or straight (indistinct in some specimens of D. collaris); frons with large and subcontiguous or confluent puncture. Clypeus rectangular or trapezoid, somewhat semicircular in females, wider than long (posterior width/length = 2.0–2.8), as punctate as frons; ventral area not vertically deflected; anterior and lateral margin slightly upturned; anterior and posterior angles rounded and slightly upturned or not, posterior angles not extended in front of canthus. Labrum horizontal and narrow. Epipharynx (Fig. 27) densely setose; anteromedial area with a transverse phoba; medial area with scarce small stout setae and scarce sensilla; posteromedial area with dense thin setae and some stout setae. Each side of preoral area (Fig. 27) with 4−6 anterior sensilla (3−4 contiguous), 3−4 inner sensilla, and 5−7 posterior sensilla. Mandible (Figs. 30–32) with incisor bearing an inwardly directed, wide tooth, dorsal area with two large punctures; molar (Figs. 33–34) transversely striated, distal striae of right molar with some minute teeth. Maxilla (Figs. 35–37) setose, cardus and stipes with some barbed setae (Fig. 35 detail), stipe with a large ventroproximal stout seta; galea bearing 8 inward directed teeth; lacinia with one tooth; palpomere I with a minute outer seta, III with about 5 long setae, IV with dorsoproximal striation. Labium (Figs. 28–29) longer than wide, submentum fused with gula; mentum with longitudinal groove; prementum fused with ligula and distal margin of ligula slightly emarginate, lobes of ligula separate from each other by a membranous line; palpus with three palpomeres. Dorsal area of ligula and hypopharynx (Fig. 28) densely setose, medial area with about 5 sensilla, lateral areas with a long outward directed seta, posterior area with a V-shaped phoba. Antennae with 9 antennomeres and 3 lamellae. Pronotum (Figs. 38–39) slightly wider than long (width/length = 1.1–1.3), widest at middle; distance between punctures 1–3 times longer than puncture diameter; anterior margin beaded, sometimes marginal bead medially indistinct, lateral margins beaded, anterior and lateral margins with some setae evidently longer than setae of disc, posterior margin not beaded; anterior and posterior angles obtuse, lateral angles rounded. Hypomeron separates from posterior fold of pronotum by an angulate margin (Figs. 39–40); dorsal area of posterior fold of pronotum separates from ventral area by an angulate margin (Fig. 39). Prosternum (Fig. 40) with a medial longitudinal carina; each precoxal area 2.5 times wider than long, smooth; posterior process (Fig. 39) rounded, wider than long and not prominent. Coxal cavities as wide as long (Fig. 40). Prothoracic leg (Fig. 41) with tibia bearing a spur and 2 outer teeth. Inner distal setae of tarsomeres I–IV similar to each other, inner setae of V similar to other area setae; claws bifid and abruptly curved; empodium short. Scutellum (Figs. 52–53) parabolic, about two times wider than long, limit of mesoscutum–scutellum angulate (Figs. 46, 51–52). Mesoventrite (Figs. 46, 50) with a raised transverse carina. Elytron punctate, elytral striae inconspicuous; humerus convex; distal knob inconspicuous; outer, distal and inner distal margins beaded, laterodistal and distal margins with marginal membrane. Mesothoracic legs (Figs. 42–43) with femur long (length/width = 3.7–3.9). Tibia with carina I distinct and II distinct in females (Fig. 42) and reduced or indistinct in males (Fig. 43); inner area of males with long setal comb. Tarsomeres I–II of male with inner long setal comb (Fig. 43). Metanotum (Figs. 48, 52) 2.4 times wider than long. Metaventrite (Figs. 49–50) wide, with setae similar to dorsal surface setae, lateral setae longer than disc setae. Pterothorax pleuron (Figs. 46, 50, 54) with mesepimeron in contact with metaventrite, this contact separates the metespisternum from mesocoxal cavity. Metendosternite (Figs. 47, 49, 51) with anterior area prominent and acute in lateral view. Posterior wing (Fig. 57) with anterior margin setose, axillary sclerites as figured (Figs. 58–63). Metathoracic legs (Fig. 44) with coxa wide (length/outer width = 2.1) and contiguous, inner process rounded and wider than long (Fig. 9). Femur wide (length/width medial = 3.0–3.3), with two longitudinal carinae between trocanter apex and each femorotibial articulation. Tibia wide (length/medial width = 2.9–3.1), abruptly enlarged on first third, medial and distal areas with similar width, carina I slightly distinct, II reduced or indistinct; apex with 2 spurs (Fig. 45). Tarsomere IV with inner distal setae thicker than those of I, inner area of V with a raised carina and with some thin setae; pretarsal claws simple and gradually curved, empodium long. Abdomen (Figs. 55–56). Pygidium of males parabolic, that of females triangular, setose and punctate, puncture with lunular peripheral stria, females with posterolateral margins internally folded (Figs. 80, 83), fold as long as half of the external surface. Males with medial area of ventrite V as long as III–IV combined, that of females as long as II–IV combined (Fig. 56); males with medial area of ventrite VI two times longer than V, that of females as long as one-third of V (Fig. 56); males with ventrite VI bearing a concavity (Figs. 25–26); intersegmental membrane VII–VIII hidden or exposed in males when pygidium–ventrite VI are distended. Spiculum gastrale (Fig. 64) with proximal piece short; sternite IX narrow, transverse and with posterior setae. Aedeagus (Figs. 65–70) with phallobasis and its apodeme wide, apodeme with a ventral thickened area, dorsum with lateral oblique prominences; parameres with lateral concavity, apex acute and ventrally deflected, inner margins setose. Endophallus (Figs. 73–77) with a wide proximal piece and a narrow distal piece; proximal piece with a long dorsal lobe, a wide ventroproximal lobe, a small ventromedial lobe and a wide ventrodistal lobe; distal piece with 1 or 3 dorsal lobes. Female terminalia (Figs. 78–83) with proctiger membranous, indistinct, but with distal raspula (Fig. 78 detail); paraprocts articulate with internal fold of pygidium (Figs. 80, 83); gonocoxites long and setose. Internal genitalia (Figs. 81, 83) with spermatheca curved, duct opening posteriorly prominent, gland of spermatheca large and connected to the distal area of the duct.
Remarks. The genera Calodactylus Blanchard, 1850 and Dasyus are similar to each other, they are distinguished by mesotibial and metatibial enlargements: Calodactylus has a medial enlargement (Fuhrmann & Vaz-de-Mello 2017: fig. 7E) and Dasyus has medial and distal areas with same width (Figs. 42–44). An evident characteristic of these genera is the simple mesotarsal and metatarsal claws, which also occurs in male Pectinosoma Arrow, 1913 and some species of Ancistrosoma Curtis, 1835, Barybas Blanchard, 1850, Ceraspis LePeletier & Audinet-Serville, 1828, and Faula Blanchard, 1850. Other conspicuous characteristic to both genera is the ventrite VI of males with a medial concavity (Figs. 25–26; see Fuhrmann & Vaz-de-Mello 2017: fig. 7B); that ventrite ornamentation is also found in males of Chariodema Blanchard, 1850 (Fuhrmann & Vaz-de-Mello 2017: fig. 9A).
description: Published as part of Fuhrmann, Juares, 2019, Taxonomy of Neotropical genera Compsodactylus and Dasyus and notes on claw movement in Macrodactylini (Coleoptera: Scarabaeidae: Melolonthinae), pp. 139-163 in Zootaxa 4679 (1) on pages 142-144, DOI: 10.11646/zootaxa.4679.1.9, http://zenodo.org/record/3466340