Metallactus quadriophthalmus, Sassi, 2015

Sassi, Davide, 2015, Two new species of Metallactus from Bolivia and Brazil (Coleoptera: Chrysomelidae: Cryptocephalinae), Acta Entomologica Musei Nationalis Pragae 55 (2), pp. 703-712 : 708-711

Metallactus quadriophthalmus sp. nov.

( Figs 4–6, 8 , 12–14, 17 , 20–21, 23 )

Type locality. Bolivia, Department of Santa Cruz, Andrés Ibañez Province, Reserva Privada Potrerillo del Guenda (10 km (air) NW of Teverinto), 17°40.26′S, 63°27.45′W, 370 m a.s.l.

Type material. HOLOTYPE: J, ‘ Bolivia Santa Cruz dpt. Andrés Ibañez pr. 18.-25.xi.2011 Potrerillo del Guenda 17°40.26’S, 63°27.45’W 370m at light L. Sekerka & D. Windsor lgt.’ [white label, printed] // ‘ Metallactus quadriophthalmus sp. nov . Holotypus D. Sassi des.’ [red, printed] ( NMPC). PARATYPES (51 specimens): 13 JJ 18 ♀♀, same data of the holotype ( NMPC, LSPC, DSCI, MNKM, MSNM, USNM) ; 1 J, 1 ♀ ‘ Bolivia, Santa Cruz Andres Ibanez Prov. Potrerillo del Guenda 6-8 December , 2011’ [white label, printed] // ‘ 17°40 S 63°20 W Wapes, Lingafelter Morris & Woodley’ [white, printed] ( JWAT, MNKM) ; 1 J, ‘ Bolivia Santa Cruz Potrerillos del Guendà 40km Santa Cruz 17°40.3‘ S 63°27.4‘ W 22-xi-12-xii-2005 coll. B.K. Dozier’ [white label, printed] ( FSCA) ; 1 J 1 ♀, ‘ Bolivia Santa Cruz Reserva Privada Potrerillos de Guendà 17°40.26‘ S 63°27.44‘ W 400m 9/ 28-xi 2006 B.K. Dozier coll.’ [white label, printed] ( FSCA) ; 1 J, ‘ Bolivia Santa Cruz Amboro National Park Los Volcanes c. 1000m S 18°06‘ W 63°36‘ 20/xi-12/xii/2004 ’ [white label, printed] // ‘MV light Sheet Barclay, M.V.L. & Mendel, H. BMNH(E) 2004-280’ [white label, printed] ( BMNH) ; 1 ♀, ‘ Bolivia Santa Cruz dpt., Andrés Ibañez pr.: Los Jubas Hacienda „Peta“ 10.xii.2011 17°52.31‘S, 62°51.60‘W 370m on vegetation D. Windsor & M. Perez lgt.’ [white label, printed] ( NMPC) ; 1 ♀, ‘ Bolivia Santa Cruz dpt. Ñuflo de Chávez pr. 28.xi-5.xii.2011 Conceptión-FCBC Alta Vista 16°08.1‘S, 61°56.1‘W 425m beating of vegetation L. Sekerka & D. Windsor lgt.’ [white label, printed] ( NMPC) ; 1 ♀, ‘ Bolivia Santa Cruz 4-6k sse Buena Vista F&f Hotel Oct 22-31 2002 Wappes & Morris’ [white label, printed] ( TAMU) ; 5 ♀♀, ‘ Bolivia Santa Cruz 3.7km sse Buena Vista Hotel Flora & Fauna 405m 5-15-xi-2001 17°29.949‘ S 63°33.152‘ W M.C.Thomas & B.K. Dozier tropical transition forest’ [white label, printed] ( FSCA) ; 1 J, ‘ Bolivia Santa Cruz, 3.7 km sse Buena Vista Hotel Flora & Fauna, 430m. ’ [white label, printed] // B.K.Dozier collector 14- 28-x-2000 ’ [white label, printed] ( FSCA) ; 1 ♀, ‘ Bolivia Santa Cruz 500m 12.V.1955 Zischka’ [white label, printed] ( ZSM) ; 1 J 1 ♀, ‘ Bolivia Santa Cruz 500m 5.XII.1960 Zischka’ [white label, printed] ( ZSM) ; 2 JJ 1 ♀, ‘ Brazil Rondônia 62 km SW Ariquemes nr Fzda Rancho Grande 8-20-XI-1994 JE Eger Black Light Trap’ [white label, printed] ( FSCA). All paratypes provided with additional label: ‘ Metallactus quadriophthalmus sp. nov . Paratypus D. Sassi des.’ [red, printed].

Description of male. Habitus in Figs 4–6, 8 . Body length: 3.85–4.25 mm; interocular distance: 0.24 ± 0.02 mm (5.9 % of total body length). Body cylindrical, slender, elongate. Head entirely pale yellow, only mandibles distinctly blackish on apical half. Vertex impunctate with dull surface; longitudinal weakly impressed and fainty pigmented line extended along frons and upper part of clypeus; clypeal area not delimited, i.e. frontoclypeal suture blurred; frontoclypeal surface fairly lustrous, with punctures arranged in two irregular and divergent rows extended from superior ocular margin to antennal insertions, further transverse arcuate row of punctures within antennal insertions. Ocular lines very distinct, long, punctate, extended down to ocular notch. Eyes bulging, in dorsal view distinctly protruding along sides of head; antennae yellow, apex of antennomeres brownish, length ratio of antennomeres: 100: 50: 90: 100: 140: 130: 120: 120: 90: 90: 100.

Pronotum yellow with barely visible reddish patch along median line; sides regularly arcuate, punctation on disk coarse, sparse, slightly denser along sides; lateral margins narrow, anterior half not or barely visible from above, anterior and posterior angles slightly protruding; faint shallow impression along posterior margin not extended beyond its inner half.

Scutellum yellow, raised, slender, arcuate laterally, with truncated apex.

Elytra almost parallel-sided, distinctly wider than pronotum, reddish, with two rounded spots on apex and in middle of disk, small elliptical periscutellar patch and subtriangular spot partly covering humera light yellow; sides slightly converging towards apex; postscutellar area slightly but perceivably raised in shape of small tubercle ( Fig. 8 ), punctation similar in size and shape to that of pronotum, arranged in quite regular rows, slightly less impressed towards apex; interstices flat.

Legs normally shaped, yellow, only apical half of unguicles bright black; tibiae sparsely covered with whitish setae; tarsi not particularly enlarged.

Ventrites and pygidium yellow with sparse, whitish setae. Prosternal process ( Fig. 17 ) broad, 1.5–1.6 times longer than wide, surface densely and coarsely punctate and pubescent, strongly impressed in middle, with lateral margins abruptly raised and slightly arcuate, posterior margin fairly raised and regularly rounded. Fifth abdominal ventrite with faint, moderately transverse impression, posterior margin not notched.

Male genitalia ( Figs 12–14 ): median lobe with maximum width in the distal half, apex triangular-shaped, setose on sides, with strong, clear-cut apical tooth; ventral surface raised in stout, strongly protruding swelling, faintly bilobate on apex; ostium transverse, basally delimited by couple of frenula separated apart by well sclerotized median lamina; protruding swelling particularly apparent in lateral view and apex almost straight.

Females differ from males in: stouter body, body length 4.10–5.13 mm, interocular distance: 0.59 ± 0.04 mm (12.6 % of total body length), prosternal process broader than in males, 1.30–1.40 times longer than wide, parallel-sided, surface slightly impressed along sides and with lateral margins moderately raised, posterior margin regularly rounded.Antennae shorter and almost totally black. Anal ventrite with deep circular pit extending across whole length of ventrite.

Rectal apparatus ( Figs 20–21 ) with two dorsal and one ventral sclerites; dorsal sclerites narrow, subrectangular, more pigmented on its anterior part, apodemes large, hyaline, bent upwards and leaning against rectum, thus barely visible in dorsal view; transverse connection across dorsal fold sinuate in middle; ventral sclerite ribbon-like, arcuate with concave anterior margin, with rounded apodemes wider than rectum and fairly more pigmented on apex; lateral fold very narrowly pigmented, devoid of sclerotizations.

Spermatheca ( Fig. 23 ) sickle-shaped, slightly pigmented; basal part not swollen; base slightly bent backwards, with gland and ductus insertions not pigmented but enlarged and well sclerotized, thus that base of spermatheca seems bifurcated; ductus quite short, slender and not coiled, its insertion on bursa copulatrix neither enlarged nor pigmented.

Variability. Specimens from Rondônia show slight differences compared to those from Bolivia: 1) punctures on frontoclypeal area are denser and more impressed; 2) median elytral yellow spot is more transverse; 3) aedeagus is more parallel-sided; 4) the apical aedeagal denticle less pronounced and distinct; 5) aedeagal ventral bump more deeply sulcate.

Differential diagnosis. In size and body shape the new taxon resembles some species of the first group of SUFFRIANʼs (1866) system, in particular M. nobilis Suffrian, 1866 , from which it distinctly differs by completely different colouration, the latter being rufous with four black elytral spots. The new species is also somewhat similar to M. semirufus Suffrian, 1866 regarding to the colour pattern. The latter is considerably smaller in size (3.20 mm in total length, compared to 4.10–4.70 mm of the new species). The new species also shows a remarkable chromatic dimorphism ( Figs 4–6 ), existing in both sexes. Five males, out of 22, and four females (out of 30), have the dorsal surface entirely yellow (‘pale form’) without reddish pattern. The perceivable raised area on the elytra, situated posteriad to the scutellum and shaped in the form of tubercle ( Fig. 8 ), is present also in other species currently attributed to Metallactus , such as M. peruanus Jacoby, 1907 . It is unclear, at present, if this character has phylogenetic significance.

Etymology. Named after the chromatic pattern of the ‘typical morph’ characterized by four rounded light spots on the elytra. The name is adjective.

Biology. Nearly all specimens from Potrerillo del Guenda were collected at lights (usually until 10 PM) during the early rainy season. Despite extensive collecting efforts in the type locality, the host plant associations of the new species remains unknown. The forest at the type locality and also at Hotel Flora & Fauna near Buena Vista is lowland semideciduous chiquitano forest (L. Sekerka, pers. comm.).

Distribution. Bolivia (Santa Cruz) and Brazil (Rondônia).

Figures

Figs 1–8. 1–3, 7 – Metallactus sekerkai sp. nov.: 1 – holotype; 2 – female, typical chromatic form; 3 – female, chromatic variation; 7 – holotype, lateral view. 4–6, 8 – M. quadriophthalmus sp. nov.: 4 – holotype; 5 – male, chromatic variation; 6 – female; 8 – holotype, lateral view. Abbreviation: psa = postscutellar area. All the figured specimens come from their respective type localities. Specimens are not figured to the same scale.

Figs 9–17. 9–11, 15–16 – Metallactus sekerkai sp. nov. 12–14, 17 – M. quadriophthalmus sp. nov. 9–14 – apex of median lobe of aedeagus (9, 12 – ventral, 10, 13 – dorsal, 11, 14 – lateral views); 15–17 – prosternal process: (15 – female; 16–17 – male).

Figs 18–23. 18–19, 22 – Metallactus sekerkai sp. nov. 20–21, 23 – M. quadriophthalmus sp. nov. 18–21 – female rectal apparatus (18, 20 – dorsal, 19, 21 – ventral views); 22–23 – spermatheca.