Bidessus anjozorobe, Bergsten & Ranarilalatiana & Biström, 2020

Bergsten, Johannes, Ranarilalatiana, Tolotra & Biström, Olof, 2020, A new species of Bidessus from Anjozorobe-Angavo and a review of Malagasy Bidessus (Coleoptera, Dytiscidae), European Journal of Taxonomy 720, pp. 1-18 : 8-9

Bidessus anjozorobe sp. nov.

urn:lsid:zoobank.org:act:C6F11BD1-C6DC-41B6-8994-35C58E062999

Figs 1C , 3C

Diagnostic characters

Head slightly posterior to frontal edge with a shallow, transverse depression, which medially is vague. Pronotum discally with broad area with fine, sparse and irregular punctures. Pronotal striae at base strongly impressed; angled (not smoothly curved). Basal striae of elytra medium long, straight (close to base, strongly curved outwards); at base quite strongly impressed. Sutural lines close to frontal edge of elytra distinct; posteriorly lines gradually fade away. Female with outline of elytra posteriorly smooth (minor process absent). Penis in lateral view curved, medially slightly straightened. Penis apex with a long and slender extension ( Fig. 3C ), a feature which separates B. anjozorobe from all other Bidessus species known from Madagascar. Considering morphology B. anjozorobe most resembles B. perrinae Bistr ̂m, 1985 thus far known from Angola. The two species are separated as follows: elytra almost unicolored dark, black to dark piceous in B. anjozorobe while distinctly bicolored in B. perrinae , elytra being brownish to dark ferrugineous with distinct testaceous markings. Furthermore, body slightly larger and more robust in B. anjozorobe than in B. perrinae (length of body 1.6 mm). See original description in Bistr̂m (1985).

Etymology

Named after the type locality Anjozorobe forest, part of the Anjozorobe-Angavo protected area. The epithet is a noun in apposition (ICZN 11.9.1.2).

Type material

Holotype

MADAGASCAR • 1 ♂; Antananarivo former province, Analamanga region, 10 km E of Anjozorobe, Anjozorobe-Angavo protected area, marsh next to the stream in Saha forest ; 18.4128° S, 47.9439° E; 1320 m a.s.l.; 23 Nov. 2014; J. Bergsten, R. Bukontaite, S. Holmgren, J.H. Randriamihaja and T. Ranarilalatiana leg.; collecting event MAD14-78; forest marsh; NHRS-JLKB000025033.

Paratypes

MADAGASCAR • 1 spec.; same collecting data as for holotype; NHRS-JLKB000025034 • 27 specs (preserved in ethanol); same collecting data as for holotype; NHRS-JLKB000025027 • 5 specs; same collecting data as for holotype; FMNH • 5 specs; same collecting data as for holotype; BMNH • 5 specs; same collecting data as for holotype; PBZT / MBC • 5 specs; same collecting data as for holotype; DEUA • 1 ♂; Antananarivo former province, Analamanga region, 10 km E of Anjozorobe, Anjozorobe Angavo protected area, Antsahabe , circuit bamboo; 18.41266° S, 47.9438° E; 1341 m a.s.l.; 5 Apr. 2016; T. Ranarilalatiana leg.; collecting event MAD16-40; marsh and stream pool; NHRS-JLKB000065489 • 1 ♀; same collecting data as for preceding; NHRS-JLKB000065490 .

Type locality

Madagascar, Antananarivo, Analamanga, Anjozorobe-Angavo Protected Area, Saha forest (18.4128° S, 47.9439° E) ( Fig. 5 ).

Description

Male

BODY. Length 1.7–1.8 mm. Dorsal aspect as in Fig. 1C . Angle between pronotum and elytra indistinct.

HEAD. Dark brown to dark piceous. Frontally between eyes not margined. Slightly posterior to frontal edge with a shallow, transverse depression, which medially is vague. Shiny although covered with fine, slightly indistinct reticulation; meshes when distinguished are isodiametric. Posterior to cervical line reticulation indistinct; surface is shagreened. With fine, sparse and somewhat irregular punctures. Posterior to cervical line impunctate. Antenna with basal segments 1–4 pale, testaceous; segments 5–11 darker; brown to piceous.

PRONOTUM. Broadest at posterior corners. Sides posteriorly straight; anteriorly clearly curved inwards. Bright testaceous; anteriorly and between striae with narrow blackish to dark brown, transverse area. At posterior corners with vague, darker spots. Discally with broad area with fine, sparse and irregular punctures. At pronotal edges punctures coarser and denser. Shiny, not reticulated.

ELYTRA. Black to dark piceous; apically with a vague, paler area. Basal striae medium long and straight (close to frontal edge strongly curved outwards for a short distance). Sutural lines close to frontal edge of elytra, distinct; posteriorly lines gradually fade away. Punctures fine to rather fine, somewhat sparse and with slightly irregular distribution. On each side of elytral stria, punctures of almost equal size and density. Towards apical region punctures become slightly finer. In frontal half of elytra with a lateral row of slightly irregular punctures. Row of punctures form a shallow but clearly discernible furrow which in posterior half disappears. Narrow area between furrow and epipleuron pale brownish and with finer and sparser punctures. Shiny, not reticulated. Epipleura pale brownish.

VENTRAL ASPECT. Pronotum testaceous, with lateral edges narrowly blackish. Metathorax, metacoxal plates and abdomen blackish to dark piceous. Rather shiny, reticulation absent. Punctures distributed as follows: metathorax medially with two rows of fine punctures and at frontal and lateral edge with a single row. Metacoxal plates medially with a few scattered punctures and at inner margin of metacoxal lines with a row of punctures. Abdomen at base with irregular coarse punctures and ventrite in apical half with dense, quite coarse punctures. Otherwise ventral aspect almost impunctate.

LEGS. Testaceous to brownish. Protarsi slightly enlarged; mesotarsi slender.

MALE GENITALIA. Fig. 3C .

Female

Similar to male but protarsi not enlarged, narrower than in male.

Distribution

Endemic to Madagascar and only known from the type locality in Anjozorobe forest, Central Highlands ( Fig. 4C ).

Collecting circumstances

The type locality is a vegetation rich marsh in a forest glade at an elevation of 1320 m a.s.l. ( Fig. 5 ). Small water pools were visible at the edges of the marsh during the visit at the end of November 2014 but mostly derived through stamping in the vegetation. Anjozorobe-Angavo forest corridor with its westerly location is a higher elevation forest and represents a transition type between typical eastern humid forest and sub-humid high plateau forest.

Figures

Fig. 1. Habitus photographs of Malagasy species of Bidessus Sharp, 1882. A. B. apicidens Bistr̂m & Sanfilippo, 1986, ♀, paratype, http://id.luomus.fi/GL.8408 (FMNH). B. B. cf. ceratus Guignot, 1941, http://id.luomus.fi/GC.2001 (FMNH). C. B. anjozorobe sp. nov., paratype (NHRS-JLKB000025034). D. B. cf. nero Gschwendtner, 1933 (NHRS-JLKB000025032).

Fig. 3. Male genitalia of the Malagasy species of Bidessus Sharp, 1882. For each subpanel from left to right penis in dorsal view, penis in lateral view and paramere in lateral view. A. B. apicidens Bistr̂m & Sanfilippo, 1986. B. B. cf. ceratus Guignot, 1941. C. B. anjozorobe sp. nov. D. B. cf. nero Gschwendtner, 1933. E. B. nesioticus Guignot, 1956. F. B. perexiguus Kolbe, 1883. G. B. longistriga Régimbart, 1895.

Fig. 5. Type locality [MAD14-78] for Bidessus anjozorobe sp. nov. in Anjozorobe forest in Anjozorobe- Angavo protected area on the Central Highlands. A glade in the rainforest with marsh vegetation. Multiple individuals of Bidessus anjozorobe sp. nov. were found by tramping in the vegetation at the edges of the marsh.

Fig. 4. Distribution maps of the Malagasy species of Bidessus Sharp, 1882. A. B. longistriga Régimbart, 1895. B. B. perexiguus Kolbe, 1883. C. B. cf. nero Gschwendtner, 1933 (circle), B. nesioticus Guignot, 1956 (square), B. anjozorobe sp. nov. (triangle). D. B. apicidens Biström & Sanfilippo, 1986 (square), B. cf. ceratus Guignot, 1941 (circle).