Metallactus planipennis Suffrian, 1866

Sassi, Davide, 2022, Revision of the Metallactus taeniatellus species group (Coleoptera: Chrysomelidae: Cryptocephalinae), Zootaxa 5125 (3), pp. 251-282 : 264-266

Metallactus planipennis Suffrian, 1866

( Figs 5 ; 15 )

Metallactus planipennis Suffrian, 1866: 268 . Clavareau, 1913: 93 (catalogue); Blackwelder, 1946: 641 (catalogue).

Types. Suffrian (1866) did not mention the number of specimens under study but stated that no males were available for study. He reported the name of a single collector (“Sello”), a single locality (“Caasapava”) and MNHUB as single type location (depository), where 3 female syntypes were found. A lectotype is here designated as follows: lectotype (by present designation): ♀, pinned // “23947” [white label, printed] // “ planipennis Suffr. * Cassap: Sellow.” [blue label, handwritten] // “ Metallactus planipennis Suffrian, 1866 LECTOTYPUS D. Sassi des.” [red label, printed] // (MNHUB). Paralectotypes: 2f ♀, pinned, no labels on the pins, but they obviously belong to the same series of the LT. Label information and the number of syntypes match the registration data from the old catalogue of the MNHUB (“23947 Metallactus planipennis Suffr. * 3. Cassapava, Sello”). Both paralectotypes labeled as follows: // “ Metallactus planipennis ( Suffrian, 1866) PARALECTOTYPUS D. Sassi des.” [red label, printed].

Type locality. Caçapava ( Brazil). Unfortunately, the available data are ambiguous, and it is impossible to say which one must be considered the exact provenance of the specimens ( Caçapava in São Paulo or Caçapava do Sul in Rio Grande do Sul) .

Additional material examined. ARGENTINA: Corr [ientes] 24 Km SE of Ità-Ibaté 20.I.1989 C.W. & L. O’Brien & G. Wibner (2, BYU) ; Chaco de Santa Fé Las Garzas Bords du Rio Las Garzas 25 KM W d’Ocampo (1, MNHN) . BRAZIL: Paranà Vila Velha 12.I.1969 (1, BYU) . PARAGUAY: 7 Km N. B. Acerval 12.X.1968 at night C.W. & L. O’Brien (1, BYU) .

Distribution. Argentina (new), Brazil, Paraguay (new).

Diagnosis. In the available specimens the black dorsal pattern is generally more extensive than in the other species studied and the longitudinal light pattern is always absent. Overall, only M. quadrinus seems to share a similar colour pattern, but in this latter species the pronotum is more transverse and more lightly punctured in males. Males are usually stouter in M. quadrinus , and the aedeagal shape is different, with the apex larger and with angulate sides.

Description of male. BL = 3.9 mm, BW = 2.3 mm, PL = 1.4 mm, PW = 1.9 mm. Interocular distance 7.7 % of BL.

Head black with blunt triangular yellow spot on frontoclypeal area. Labrum brownish. Surface with few, small punctures, short semi-erect setae, distributed mostly on vertex, along ocular edges and between antennal sockets. Mid-cranial suture narrow but well detectable from vertex to yellow spot on frontoclypeus. Ocular lines narrow, strictly adhering to ocular rim, marked by a line of punctures slightly departing from ocular rim just beside ocular canthus, whose surface is almost impunctate. Ocular canthus deep, rounded with few, short setae. Antennae ( Fig. 5h ) brownish. First five antennomeres sublucid, 3-5 rod-shaped, 6-11 dull, flattened and more diffusely setose.

Pronotum black with two yellow stripes covering lateral margins. Pronotal outline rather lengthened, elliptical, almost regularly convex on middle and anterior part of disc, fairly flattened towards base. Lateral margins thin, not visible in dorsal view, regularly curved reaching maximum width at middle. Surface shining with well impressed, regularly distributed punctation. Posterolateral impressions obliterated.

Scutellum black, distinctly raised, finely setose and very minutely punctured. Apex slightly rounded.

Elytron black with a yellow spot on outer humeral area, extended to lateral margin. Second rounded yellow spot covering apical clivus up to posterior margin. Epipleuron yellow. Elytral outline almost parallel-sided. Elytron very weakly flattened on disc. Lateral margin narrow, barely visible in dorsal view. Elytral surface matt, covered with well-impressed punctures arranged in irregular rows. Intervals slightly raised and connected here and there by faint transverse wrinkles. Postscutellar area slightly raised. Humeral callus prominent, impunctate. Epipleuron smooth, impunctate, convex.

Pygidium brownish with two hooked yellow spots along sides, smooth, matt, covered by sparse shallow minute punctures and short setae.

Ventral parts of thorax totally dark black. Abdominal ventrites dark brown with yellow border along sides. Hypomera shiny, bare, with scarce, scattered punctures. Mesoepimera and mesoepisterna with surface partly rugulose, bearing scattered setae and shallow punctures. Rest of ventral surface matt, shallowly punctured, with a covering of sparse, appressed setae. Prosternal process longitudinally grooved, sparsely punctured with long setae and flat, short apex. Legs totally brownish.

Median depression on fifth abdominal ventrite shallow but fairly delimited from the rest of ventrite surface, shiny, bare and impunctate. Ventrite posterior margin raised, straight. Median lobe of aedeagus ( Fig. 5c–e ) compressed laterally, with expanded apex, well differentiated from shaft, terminated by small median denticle. In lateral view apex slightly bent ventrally. Ventral outline fairly convex but roughly depressed in middle. Setose depressions deeply impressed, ear-shaped, separated by wide, blunt carina and bearing few, short, curly setae.

Endophallus ( Fig. 5f ) with sclerite I slender, well developed and pigmented, distinctly bent downward at middle, denticle apparent. Dorsal spicule not detectable. Sclerite II well developed, short and strongly pigmented. Arch of sclerite III sickle-shaped, short, regularly curved, with pointed apex. Branches of sclerite IV equivalent in length to sclerite III in folded-up structure, distinctly arched towards ventral direction, with shortly tapered apex and surface smooth.

Female. Habitus in Fig 5 a-b (LT). BL = 4.8–5.4 mm, BW = 2.8–3.2 mm, PL = 1.5–1.8 mm, PW = 2.4–2.8 mm. Interocular distance 14.6–14.8 % of BL.

Females differ in a stouter body, larger interocular distance, pronotal shape tronco-conical and with the lateral margins more convergent anteriorly, such that the maximum width is more towards the posterior margin. Additionally, the yellow marking on the frons is smaller and the yellow lateral stripe on the pronotum is generally more extended towards the midline or as in the lectotype, large and limited to the basal half.

The fifth abdominal ventrite in females has a large, rounded, impressed pit. The bottom of the pit is glabrous, covered with sparse shallow punctures. The vasculum of the spermatheca ( Fig. 5g ) is slender, moderately pigmented, S-shaped with a non-swollen proximal lobe and distal lobe abruptly tapering to a slender apex that is slightly bent downwards. The ampulla is not or scarcely pigmented, sitting just at the basal apex of the vasculum. The duct and sperm gland insertions are perceptibly distinct. The duct is robust and quite rigid beside the vasculum, forming a packed series of turns more than coils, then slender and almost straight. The turns of the duct vary from several (about 12 as in Fig. 5g ) to few (about 2-4). The insertion on the bursa copulatrix is robust, conical, strongly pigmented.

Remarks.

In one female from Brazil (Paranà) the pronotum is black with a large square yellow patch in the middle of the disc. This latter specimen is also more robust with a coarser covering of punctures on the forehead. The spermatheca is also different in that the vasculum is more robust and the duct forms more turns beside the vasculum. At present, the taxonomic significance of these differences, if any, is difficult to evaluate .

Figures

FIGURES 5–6. M. planipennis (5), M. quadrinus (6). 5a–b: habitus (LT); 5c–e: median lobe of aedeagus in ventral (c), dorsal (d) and lateral (e) view [0.7 mm]; 5f: sclerites of endophallus [0.4 mm]; 5g: spermatheca [0.3 mm]; 5h: antenna [1.1 mm]. 6a–b: habitus (LT); 6c–e: median lobe of aedeagus in ventral (c), dorsal (d) and lateral (e) view [0.6 mm]; 6f: sclerites of endophallus [0.4 mm]; 6g: spermatheca [0.3 mm]; 6h: antenna [1.0 mm]. scI–IV: sclerites I–IV of endophallus. Square brackets: length of scale segment.

FIGURES 15–18. Distribution maps for the Metallactus taeniatellus species group. M. planipennis (15); M. quadrinus (16); M. superbiens (17); M. taeniatellus (18). Striped squares: two possible (alternative) locations for the type locality of M. planipennis due to the ambiguous report in the original description (see text for further information).