Laccodytes costae sp. nov., and new records for the genus from Brazil (Coleoptera: Dytiscidae)

. Laccodytes costae sp. nov., from Brazil, is described and illustrated; the new species is the third known member of the Laccodytes apalodes species-group. New records for Brazil: Laccodytes americanus Peschet, 1919, new for the country and Laccodytes rondonia Toledo, Spangler & Balke, 2010, new for the state of Pará. A modified version of the key from Toledo, Spangler & Balke (2010) is provided with new couplets to allow the identification of the new species as well as L. cobreinae Toledo, Megna & Alarie, 2011.


INTRODUCTION
Laccodytes Régimbart, 1895 is a Neotropical diving beetle genus, currently with 11 species, which inhabits running water (Nilsson & Hajek, 2019). The genus was characterized by Miller & Bergsten (2016) and included within the tribe Laccophilini by having: (1) metatibial spurs apically not bifurcated; (2) prosternal process moderately broad, apically simple and acuminately pointed, not laterally compressed; (3) posteromedial margin of the pronotum angulate; (4) posterolateral angles of the pronotum obtusely angulate to sharply pointed; (5) metacoxal lines somewhat divergent anteriorly. Toledo et al. (2010) reviewed the genus and divided it into the L. apalodes and L. phalacroides species groups. The first has two species and is characterized by having a long, needle-like prosternal process extended caudally past the mesocoxae for a third of its length; acute posterior pronotal angles; membranous expansion on the median lobe of the aedeagus and slightly dilated male pro-and mesotarsomeres 1-3. The L. phalacroides-group, including all other nine species, is characterized by a shorter tip of the prosternal process, not going beyond mesocoxae or very hardly so; rounded posterior angles of pronotum; median lobe of the aedeagus lacking membranous expansions; and male pro-and mesotarsi not dilated.
The new species described here has a color pattern inedited for the genus and belongs to the L. apalodes group, presently composed of only two species. We are also providing new geographic data for L. americanus Peschet, 1919 andL. rondonia Toledo, Spangler &. The identification key from Toledo et al. (2010) is herein updated and modified to accommodate all currently known species.

MATERIAL AND METHODS
The specimens were examined under a stereomicroscope with up to 150 times magnification. The measurements were obtained with the aid of an ocular grid with an accuracy of 0.01 mm, and specimens were preserved in tubes with 96% ethyl alcohol. The dissected genitalia were kept in glycerine and mounted on slides with coverslips for drawings and finally stored in microvials attached to the specimen. The terminology used in the descriptions and keys follows that of Toledo et al. (2010). The

Diagnosis:
This new species is distinguished from other species of the genus by the following combination of characters: total length 1.4 mm (both examined specimen); prosternal process with thorn-shaped tip, extended caudally beyond mesocoxae; posterior angle of pronotum produced backward, acute; head, pronotum and ventral side yellow; each elytron yellow with a pattern of dark longitudinal lines; apex of elytra rounded.

Coloration (Figs. 1, 3-4):
Head and pronotum yellow; each elytron yellow with five longitudinal dark lines (Fig. 4), alternating long and short lines: the three longer with the length going from the base to the final quarter of the elytron and the three shorter covering the middle third of the disc (Figs. 1, 4). Ventral side of head, epipleuron, legs and abdomen yellow; yellow prosternal process darkening to light brown at apex; metasternum light brown and metacoxae yellow darkening to light brown on the posterior margin (Fig. 3).

Sculpture (Figs. 2a-d):
Dorsal surface with microreticulation, consisting of small somewhat irregular cells and small punctures scattered on whole dorsal surface ( Fig. 2a-c). Line of punctures accompanying apical mar-gin of pronotum. Ventral surface with microreticulation, consisting of small somewhat irregular cells and small punctures scattered on whole surface (Fig. 2d).

Etymology:
The specific name is an homage to Dr. Cleide Costa, an important Brazilian Coleopterologist. The specific name stands as a noun in apposition to the generic name.
Geographic distribution: Only known from Amazonas State, Brazil.
Taxonomic notes: Laccodytes costae sp. nov., has an acute posterior pronotal angles and a long extended prosternal process caudally past the mesocoxae, very similar in shape to L. rondonia. Although the other two species of L. apalodes-group have a longer process extending caudally, past the mesocoxae for a third of its length, and L. costae sp. nov., for a fourth of its length, the similar shape of process and the acute pronotal angles indicate this new species is the third species to L. apalodes-group. Only females were found, but they have characteristics that are unique within the genus. The yellow color with longitudinal darker lines in the elytron is unique, as known members of the genus usually are darkly colored with clear wide transverse strips or maculae. In addition to coloration, this species is one of the smallest species of the genus, comparable only to L. olibroides Régimbart, 1985, a member of the L. phalacroides-group, which has nearly entire body with a dark patterning.   Braga, R.B. & Ferreira-Jr., N.: Laccodytes costae sp. nov., and new records of Laccodytes Pap. Avulsos Zool., 2020;v.60.special-issue: e202060(s.i.).17 3/4