Aegidium atlanticum Frolov, Grossi

Frolov, Andrey V., Grossi, Paschoal C. & Vaz-De-Mello, Fernando Z., 2015, A new species of Aegidium Arrow (Coleoptera: Scarabaeidae) from the Atlantic forest ecoregion in South America, Zootaxa 4007 (3), pp. 437-439 : 437-439

Aegidium atlanticum Frolov, Grossi , & Vaz-de-Mello, new species

Figs. 1–3.

Type material. Holotype, male: “ BRAZIL: RJ 1500 m Nova Friburgo Macaé de Cima [22.375291°S, 42.493974°W] 13.II.2000 P.Grossi” (Insect Collection, Federal University of Mato Grosso, Cuiaba, Brazil).

Holotype description. Male (Fig. 1). Body length 13.5 mm, width of elytra 6.5 mm, width of pronotum 6.0 mm. Upper side of body shiny, color uniform dark brown.

Clypeus symmetrical, with straight anterior margin and rounded anterior angles. Head surface densely punctate with round punctures separated by 1–2 puncture diameters on clypeus becoming denser and coarser on frons near eyes. Head without traces of medial horn or tubercle. Mandibles symmetrical, protruding past anterior margin of clypeus. Labrum rounded, small, slightly protruding past clypeus (in dorsal view).

Pronotum 1.25 times wider than long, widest at middle. Anterior margin with a border interrupted medially by a tubercle. Lateral margins crenulate. Base not bordered. Disc of pronotum excavated in middle. Surface irregularly punctate: with rather sparse, round punctures anterolaterally, somewhat coarser round punctures posterolaterally, irregular coarse punctures on disc and a row of longitudinally elongate punctures along base.

Scutellum elongate, rounded apically, about 1/12 length of elytra, smooth.

Elytra of typical Aegidium shape—moderately convex on disc with maximum width approximately at middle. Humeral and apical humps distinct. Elytra with 2 longitudinal ridges (smooth elevated areas) on disc between suture and humeral hump. First (sutural) elytral interval somewhat elevated on disc similar to longitudinal ridges. Striae almost indistinct. Elytra densely punctate with coarse, irregularly shaped punctures arranged in longitudinal rows on disc. Base of elytra not bordered.

Wings fully developed.

FIGURES. 1–2, Aegidium atlanticum , holotype: 1—habitus; 2—aedeagus in lateral and dorsal view. 3—locality map of the known distribution of Aegidium (▲— A. atlanticum , ●—other species of Aegidium ; basemap ecoregion legend: 1—tropical and subtropical moist broadleaf forests, 2—tropical and subtropical dry broadleaf forests, 3—tropical and subtropical coniferous forests, 4—temperate broadleaf and mixed forests, 5—tropical and subtropical grasslands, savannas, and shrublands, 6—flooded grasslands and savannas, 7—montane grasslands and shrublands, 8—mediterranean forests, woodlands, and scrub, 9—deserts and xeric shrublands, 10— mangroves).

Protibiae with 3 outer teeth and a smaller inner tooth. Lateral margin basad of outer teeth slightly crenulate. Apex and internal margin of tibia with a few slender setae. Protarsi about 1/2 length of protibiae. Claws 1/3 length of tarsomere 5, which is somewhat longer than tarsomeres 3 and 4 combined, and somewhat thicker than other tarsomeres. Tarsomere 1 as long as tarsomeres 2–4 combined. Ventral surface of femora punctate with rounded punctures.

Mesolegs and metalegs similar in shape; metafemora and metatibiae about 1.2 times longer than mesofemora and mesotibiae. Femora sparsely punctate with rounded punctures. Tibiae somewhat triangular, with two apical spurs. Upper tibial spur somewhat shorter than tarsomeres 1–3 combined; lower spur a bit shorter than tarsomeres 1–2 combined. Claws 1/3 length of tarsomere 5, which is relatively slender, as long as tarsomere 2 and twice as short as tarsomere 1.

Abdominal sternites punctate with coarse irregularly shaped punctures. Sternite 8 medially about 2 times wider medially than sternites 4–7.

Pygidium triangular, convex, partly hidden under elytra, irregularly punctate with transverse punctures.

Aedeagus. Phallobase 1.5 times longer than parameres, tube-shaped, with a deep triangular excavation venrtobasally. Parameres strongly curved downward, at acute angle to the phallobase (in lateral view); of complex shape (Fig. 3). Apices of the parameres are separated by a constriction and there are long feebly sclerotized processes bazad of the constriction on each paramere.

Female. Unknown.

Diagnosis. The new species can be easily separated from the other described congeners by the shape of the parameres having three apical processes.

Etymology. From Latin, “ atlanticum ” for Atlantic rain forest distribution.

Distribution and habitat. The new species is known from a single specimen collected during the day from under a dead log. The site where it was collected belongs to the State Park of Três Picos, called Macaé de Cima, within the altitude range of about 700 to 2200 m. From 1500 m and up the forest is called Upper Montane Rain Forest, or Cloud Forest, with the fog occurring during the most part of the day and the high humidity level during the year. The life cycle of the species remains unknown. Despite almost two decades of collecting in this area by P.C.G., no other specimens were found. This might be a result of a very short flying period and cryptic, probably geobiont, life style.

Remarks. The shape of the parameres of the new species is distinct from that of the other species of Aegidium (see Paulian 1984) and remarkably similar to that of the recently found monotypical genus from the Andean cloud forest ( Frolov & Vaz-de-Mello 2015). The other characters (shape of the mandibles, sculpture of the body, characteristic longitudinal elevated areas on the elytra), however, agree well with the diagnosis of Aegidium . The both taxa occur in the cloud forests at high altitudes—biocenoses that are known to preserve more archaic faunal elements than the other types of tropical forests. The peculiar complex shape of the parameres of Ae. atlanticum sp. n. might be a plesiomorphy inherited from the common ancestor of the two taxa but lost at the very beginning of the Aegidium diversification.

When handled, the live beetle uttered a noise of a rather high frequency produced apparently by the coxa-abdominal stridulatory apparatus.