Plistonax albituberculatus Silva Júnior & Souza, 2019

Júnior, José Osvaldo Silva, Haseyama, Kirstern Lica Follmann & Souza, Diego De Santana, 2019, New species and new combination in the genus Plistonax Thomson, 1864 (Cerambycidae, Lamiinae, Acanthoderini), Zootaxa 4679 (2), pp. 392-396 : 393

Plistonax albituberculatus Silva Júnior & Souza , sp. nov.

Type locality. Brazil, Rio de Janeiro: Rio de Janeiro, Grajaú, Serra dos Três Rios .

Description. Holotype male ( Figs. 1–7 ). Body in general covered with yellowish-brown setae, with white setae in some parts. Head. Frons with sparse punctation, more concentrated at center and between ocular lobes; antennal tubercle obtuse; lower ocular lobe rounded at inner and anterior margins, outer and posterior margins slightly transverse; upper ocular lobe semi-oval, with outer margin most rounded than inner. Gena shorter in length than lower ocular lobe, with sparse decumbent setae. Antenna. Scape and pedicel covered with white setae. Pedicel approximately a quarter of the scape length. Antennomere III subequal to scape in length, antennomere IV slightly shorter than antennomere III, antennomeres V–XI gradually decreasing in length. Two brown stains on antennomeres III and IV, one near base, another near apex; a single apical brown stain on antennomeres V-XI. Antenna reaching elytral apex at antennomere VIII or IX. Prothorax. Pronotum transverse, with a pair of conical lateral tubercles, covered with white setae; with two obtuse tubercles at middle-center region; median longitudinal crest present, from anterior margin to about posterior quarter; with a row of coarse punctation near anterior and posterior margins, shallower at median region. Prosternal process curved, slightly expanded toward apex, with slight expansions on lateral margins of median region; apical region expanded on both sides around procoxa, with median depression.

Mesothorax. Scutellum oblique, with straight apex, same color of elytra. Mesoventral process width shorter than diameter of mesocoxa, slightly narrowed toward apex; apex bifid; basal tubercles slightly prominent. Elytra. Convex, approximately four times length of pronotum; humeri rounded and protuberant. Median-basal crest starting at base, reaching approximately middle of elytra; crest with small black ridges in upper anterior region. White setae covering median-basal region; three pairs of brown stains (one at anterior region, two at posterior region) before elytral slope; slope with a track of white setae; margin with stains of whitish setae. Punctation with single semi-erect white seta inserted internally; elytral apex truncate. Legs. Femora club-shaped, covered with white setae; tibiae surrounding by two brown stains, with the subapical stain incomplete on the ventral face. Tarsi distinctly smaller than tibiae; protarsi flattened, with fringes of black setae; meso- and metatarsi with tarsomere I subequal in length to tarsomeres II–V together. Tarsi I and V covered with white setae, II–IV covered with brown setae. Abdomen. Segment V subequal in length to III and IV together. Segment V narrowed toward apex, with apex truncate.

Female ( Figs. 8–9 ). Antenna reaching elytral apex at antennomere X or XI. Abdominal segment V rounded, slightly truncate at apex, with short longitudinal middle-basal sulcus.

Variations. The shape of white stains on elytra can vary. Some of pairs of post-median brown stains of elytra may be indistinguishable from widespread yellowish-brown setae. Basal tubercles of mesosternal process can be absent.

Type material. Holotype (♂): Distrito Federal [ Brazil, Rio de Janeiro], Serra dos Três Rios, Grajaú, 28.X.54 [1954], Newton Santos col. Plistonax albituberculatus Silva Júnior & Souza, 2019 (Holotype ♂) . HOLOTYPE ( Fig. 6 ) ( MZSP) . Paratypes (1 ♀, 4 ♂): 1 ♂, Brazil, Bahia, Ilhéus , CEPEC, 09.XI.66, A. Gomes col., 1540 ( MZSP) ; 1 ♂, Brazil, Bahia, Ilhéus , CEPEC, 24.II.1967, A. Gomes col., 1885 ( MZSP) ; 1 ♀, Distrito Federal [ Brazil, Rio de Janeiro], Serra dos Três Rios, Grajaú, 25.X.54 [1954], Newton Santos ( MZSP) ; 1 ♂, Distrito Federal [ Brazil, Rio de Janeiro], Serra dos Três Rios, Grajaú, 28.X.54 [1954], Newton Santos, 330, UFMG-ICO 1902647 ( CCT-UFMG) ; 1 ♂, Brazil, Rio de Janeiro, Dec., Acc. No. 2966 ( MZSP) .

Measurements (mm). Holotype: total length, 9.9; length of pronotum, 1.9; width of pronotum, 3.2; humeral width, 3.8; length of elytra, 6.8. Paratypes male: total length, 9.0–11.1; length of pronotum, 1.8–2.3; width of pronotum, 3.0–3.7; humeral width, 3.6–4.7; length of elytra, 6.3–7.7. Paratype female: total length, 10.7; length of pronotum, 2.1; width of pronotum, 3.6; humeral width, 4.3; length of elytra, 7.

Etymology. The specific epithet is allusive to the stain of white setae covering the lateral tubercles of the pronotum ( Fig. 5 ), which is the main feature that distinguishes Plistonax albituberculatus sp. nov. from other species of the genus.

Comments. The new species is similar to Plistonax bialbomaculatus (Zajciw, 1964) and Plistonax rafaeli Martins & Galileo, 2006 in general appearance, body size, and by having elytral apex truncate and median-basal crests reaching approximately half of the elytra. However, P. bialbomaculatus and P. rafaeli are only known from the Amazon region. Plistonax albituberculatus sp. nov. can be differentiated from all species of the genus by having, together, the lateral tubercles of the pronotum and tarsomeres I and V densely covered by white setae, and abdominal tergite V without sexual dimorphism related to its length.

Figures

FIGURES 1–7. Plistonax albituberculatus Silva Júnior & Souza sp. nov., holotype male.1. Dorsal habitus; 2. Ventral habitus; 3. Lateral habitus; 4, Head, frontal view; 5. Prothorax, dorsal view; 6. Labels; 7. Elytra, detail of punctation and setae.

FIGURES 8–9. Plistonax albituberculatus Silva Júnior & Souza sp. nov., paratype female. 8. Dorsal habitus; 9. Ventral habitus.