Austrolimnius uncatus, Miranda, Gustavo Silva De, Sampaio, Brunno Henrique Lanzellotti & Passos, Maria Inês Da Silva Dos, 2012

Miranda, Gustavo Silva De, Sampaio, Brunno Henrique Lanzellotti & Passos, Maria Inês Da Silva Dos, 2012, Two new species of Austrolimnius Carter & Zeck (Insecta: Coleoptera: Elmidae) from Southeastern Brazil, Zootaxa 3389, pp. 14-24 : 15-20

Austrolimnius uncatus sp. nov.

( Figs.1 a,b–2a,c,d,f,g)

Diagnosis. Austrolimnius uncatus sp. nov. has long setae on the apical 2/5 of the tibiae and the tarsomeres of the median leg. Median expansion on the hind tibiae, with spines on the apical 2/3, prominent from before the medial expansion and a fringe of tomentum on the apical 2/5. Median lobe and parameres prominently curved ventrally on the apical third, resembling a hook; long setae in ventral direction on the second third of parameres.

Description. Holotype: male. Total length 2.10 mm; head width 0.70 mm, length 0.43 mm; pronotum width 1.15 mm, length 1.02 mm; elytra width 1.60 mm, length 2.72 mm. Body ( Figs. 1 a,b) short and oval with surface dark brown; antennae, mouth parts and legs reddish brown.

Head. Without distinct impressions. Surface with punctures smaller than the facets of the eyes, separated by the distance of their diameter. Eyes small and not prominent. Filiform antennae with 11 antennomeres of subequal length and with inconspicuous setae. Clypeus slightly broader and shorter than labrum with anterior margin truncate and lateral angles rounded. Labrum with anterior margin truncate and lateral angles rounded; lateral margins with short pale setae except at the median portion near the anterior margin. Maxillary palpus and labial palpus with four and three palpomeres, respectively.

Thorax ( Figs. 1 a and 2a). Pronotum slightly wider than long; anterior margin feebly rounded and narrower than the posterior margin; punctures of surface much smaller than the facets of the eyes, separated by twice their diameter on the posterior half and by one diameter on the anterior half; a pair of complete sublateral carinae present; pronotal disc with median longitudinal impression well marked from the posterior margin of the pronotum (in front of scutellum), where it is deep and wide, to the anterior margin, where it is narrow and shallow. Impression surface with punctures similar to those of the pronotal disc. Elytra longer than wide with micropunctures separated by 3–4 times their diameter; seven rows of punctures; four punctate stria between internal margin of elytra and inner sublateral carina; area between inner sublateral carina and outer sublateral carina with two punctate stria; area between outer sublateral carina and lateral margin of the elytra with one punctated stria; all surface of the elytra with punctation of equal diameter; outer sublateral carina extending up to the second abdominal ventrite; inner sublateral carina extending from the base of the elytra to the middle of the fourth abdominal ventrite; area among the stria smooth. Epipleura with tomentum and one row of granules. Oval scutellum ( Fig. 1 a) slightly convex.

Prosternum longer than wide, with anterior margin convex and wider than the posterior margin. Prosternal process ( Fig. 1 b) as wide as the concavity of the forecoxae, with a rounded apex. Mesosternum with deep and feebly wide groove. Median area of meso- and metasternum and abdominal ventrites with smooth surface, but lateral areas with tomentum. Fore femur with fringe of tomentum on the basal 2/3 on the anterior surface; fore tibiae with fringe of tomentum on the apical 2/5 of the anterior surface. Middle femur with tomentum similar to that of the fore femur, on the posterior surface; middle tibiae with row of large setae on the apical 2/5. Hind tibiae with a median expansion with spines on the apical 2/3, prominent since before the median expansion; fringe of tomentum on the apical 2/5. Tarsi with five tarsomeres, tarsomeres I–IV subequal in length; tarsomere V as large as the other four proximal together; tarsomeres of middle tarsus with numerous long setae on ventral surface ( Figs. 1 b and 2c).

Genitalia ( Figs. 2 f,g). Median lobe and parameres subequal. In lateral view median lobe and parameres prominently curved on the apical third, forming a hook-like structure ( Fig. 2 g); on the second third of the parameres, a row of prominent ventral setae present; the basal setae are shorter than those in the middle, which are the larger; as soon as the middle of this third is reached, the setae decreases in size, fading near the apex. In ventral view, median lobe gets narrower in the apical fifth ( Fig. 2 f). Apex of the median lobe rounded and the parameres slightly acuminate.

Type material.

Brazil, São Paulo, São José do Barreiro municipality, Serra da Bocaina National Park - Holotype. Male, tributário do Rio Mambucaba, Córrego Barra Branca, cascalho, 05/VIII/2004, Henriques-Oliveira, A.L. leg. ( DZRJ 5566). Paratypes. 2 males, same data as holotype, Henriques-Oliveira, A.L. leg. ( DZRJ 5568); 1 male, Fazenda Barreirinha, tributário do Rio Mambucaba, pedra, 05/VIII/2004, Henriques-Oliveira, A.L. leg. ( DZRJ 5570); 1 male, same data, cascalho, 06/VIII/2004, Henriques-Oliveira, A.L. leg. ( DZRJ 5567); 1 male, same data, cascalho, 07/VIII/2003, Henriques-Oliveira, A.L. leg. ( DZRJ 5569); 1 female, Fazenda Barreirinha, cascalho, 07/VIII/2003, Henriques-Oliveira, A.L. leg. ( DZRJ 5577); 1 female, same data as holotype, pedra, 05/VIII/2004, Henriques- Oliveira, A.L. leg. ( DZRJ 5582). Brazil, Rio de Janeiro, Nova Friburgo municipality — 1 male, tributário do Rio Santiago, pedra, 22º20,884’S; 42º23,620’W, 25/VII/00, Nessimian & Huamantico leg. ( DZRJ 5221); 2 males, same data, 25/VIII/00, Nessimian & Huamantico leg. ( DZRJ 5222).

Etymology. Species name is a Latin adjective uncatus (hooked), referring to the shape of male genitalia.

Comparative notes. The body shapes of Austrolimnius species are very similar. Among the species with one row of epipleural granules ( A. laevigatu s, A. bocainensis sp. nov. [described subsequently] and A. pilulus ), A. uncatus sp. nov. shares with these three species the short and oval body form. Additionally, A. uncatus sp. nov. resembles A. laevigatus and A. pilulus due to the presence of long setae on the middle tarsus. But, there are features of the hind tibiae that are useful for separating the species: A. uncatus sp. nov. has an expansion at the medial portion with spines on the distal half, without a concavity; A. laevigatus also has an expansion at the median portion, but with a concavity on the distal margin with spines; and A. pilulus has an expansion on the basal 2/5 with a smooth concavity on the posterior surface of the tibiae. Without careful observation, A. uncatus sp. nov. can easily be misidentified with A. laevigatus since both species have setae on the middle tarsus, and a median expansion and spines on the distal half of the hind tibiae. But, A. uncatus sp. nov. does not have setae on the antennomeres, which are present on A. laevigatus , a key character to differentiating these species. Moreover, the male genitalia of A. uncatus sp. nov. has a unique morphology among the Brazilian species. Austrolimnius uncatus sp. nov. has long ventral setae on the parameres, and the parameres and the median lobe prominently curved ventrally, characters that are not present in any other species of the genus in the region.

The new species can be easily distinguished from Austrolimnius eris Hinton , A. formosus , and A. pusio Hinton by the number of rows of granules on the epipleura. Austrolimnius uncatus sp. nov. has just one row while the other species have two. Austrolimnius uncatus sp. nov. can also be differentiated from A. formosus by two other characters: the body being short and oval in the new species, while it is fusiform in A. formosus ; and the male genitalia, which has a hook-like shape, and the parameres and median lobe are subequal length in the new species, whereas in A. formosus the male genitalia does not have any curvature and the parameres are much longer than the median lobe. Austrolimrius eris and A. pusio can also be easily distinguished from the new species by the absence of the longitudinal impression on the pronotum, a feature that is present on A. uncatus sp. nov.

Figures

FIGURE 1. Austrolimnius uncatus sp. nov. a—Dorsal habitus. b—Ventral habitus; the arrow on the left indicates the spines on the hind tibiae, and the arrow on the right indicates the fine long setae of the middle tarsus. Austrolimnius bocainensis sp. nov. c—Dorsal habitus. d – Ventral habitus (Scale bars: 1 mm).

FIGURES 2. a— Austrolimnius uncatus sp. nov. dorsal view of pronotum. b— Austrolimnius bocainensis sp. nov. dorsal view of pronotum. c— Austrolimnius uncatus sp. nov. mid-tarsus. d— Austrolimnius uncatus sp. nov. hind tibiae. e— Austrolimnius bocainensis sp. nov. hind tibiae. f and g — Austrolimnius uncatus sp. nov. male genitalia: f—Ventral view. g—Lateral view. h and i — Austrolimnius bocainensis sp. nov. male genitalia: h—Ventral view. i—Lateral view. (Scale bars of figures f, g, h and i: 0.1 mm)