Metallactus patagonicus Suffrian 1866
Creators: name: Sassi, Davide
Publisher: name: Zenodo
Year: 2018
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Chrysomelidae
Metallactus
Metallactus patagonicus

description: Metallactus patagonicus Suffrian, 1866
(Figs 10; 32)
Metallactus patagonicus Suffrian, 1866: 353; Clavareau, 1913: 93; Blackwelder, 1946: 641; McFayden, 1987: 329.
Type material. According to Suffrian (1866), the type series had been constituted only by females and one specimen should have been housed in MNHUB. However, a thorough investigation did not produce any positive result, so that the Berlin syntype must be considered lost. On the other hand, two syntypes were traced in BMNH. The typification has been made as follows. LECTOTYPE: ♀, pinned, // “125” [white label, handwritten] // “67.56” [white label, handwritten] // “a D. Suffrian determinat.” [white label, printed] // “ patagonicus Guer. ” [blue label, handwritten] //” Metallactus patagonicus Suffrian, 1866 LECTOTYPUS D. Sassi des.” [red label, printed] // (BMNH). The second female, same data, was labelled as paralectotype: 1♀, pinned, // “ Metallactus patagonicus Suffrian, 1866 PARALECTOTYPUS D. Sassi des.”[red label, printed] // (BMNH).
Type locality. “ Patagonien ” (Argentina).
Further material examined. ARGENTINA: Cordoba Fanti Sierra de Cordoba 11.I.1966 (1♂, HNHMB); Cordoba dept. Calamuchita “El Sauce” XII.1938 (1♀, USNMNH).
Distribution. Argentina.
Diagnosis. Unfortunately, because of their poor conditions, type specimens provide a limited amount of information in order to identify the very peculiarities of the species. In the original description Suffrian himself claimed: “ Actually, I have a fair number of specimens but all of them are poorly preserved so that the description will be completed in the future...”. However, after some hesitation, I decided to attribute two rather fresh specimens, a male and a female, to the present species. The following redescription of the taxon is mostly based on this new material.
The size is remarkable, and the tronco-conical pronotum is clearly distinguished from the more transverse one of M. albipes and relatives having comparable size. Besides, the pronotal black pattern of both the type specimens is clearly different in comparison with the other taxa, but it is impossible to evaluate the real effectiveness of this trait, being the pronotal coloration fairly variable within most of the species. Antennae are characteristically elongated in male. In the examined female specimens antennae are missing or strongly damaged, but they seem not to be as lengthened as in males. Similar antennal male elongation is also present in M. kollari, M. pollens and M. longicornis. Besides, in the latter two species the pronotum is more or less as clearly lengthened as in M. patagonicus, but it is possible to distinguish all these species to each other on the basis of dorsal coloration and, above all, comparing aedeagus and endophallus shape, which is remarkably different (see the respective descriptions and the identification key). As a matter of fact, being fairly bulging beneath apex, with apex clearly bent ventrally, aedeagus is very characteristic and diagnostic in M. patagonicus. Endophallus is rather typical as well because of the strong development of dorsal spicule. Similar shape in dorsal spicule is also present in M. rileyi. However, the latter species shows stouter antennae in male and aedeagal apex more distinct from tube, which is fairly different also in lateral view. Besides, in M. rileyi pronotal color pattern is more extensively black and abdominal ventrites almost completely yellow. Interestingly, dorsal spicule with comparable morphology are present in species belonging to the different and provisionally established “ M. hamifer species-group”, characterized by a clearly different external habitus (Sassi, in preparation).
Description of male. BL = 5.6 mm, BW = 3.2 mm, PL = 1.8 mm, PW = 2.7 mm. Interocular distance 9.8% of BL.
Head yellow with vertex and antennal insertion black. Labrum brownish, sometimes partly yellow. Surface dull with scattered, shallow punctures, denser on clypeus and close to inner ocular rim, sparser and shallower on vertex. Mid-cranial suture apparent, reaching upper part of vertex. Setosity sparse, more developed on clypeus, labrum and close to ocular rim. Antennae characteristically lengthened. First five antennomeres mostly black with only apex somewhat lighter and the subsequent totally darkened, dull and more diffusedly setose.
Pronotum yellow with posterior margin narrowly blackish. Six black paired spots transversally arranged on disc. Inner pair subelliptical, median one dumbbell-shaped, outer one small, rounded to slightly elliptical. Pronotal shape subconical with lateral margins narrow, almost straight. Posterolateral impressions almost obliterated to barely visible, so that posterior margin only faintly swollen on sides. Surface moderately lustrous with very sparse, moderately impressed, uneven punctures, somewhat obliterated on posterior middle part of disc.
Scutellum black, moderately raised, subsquared with truncated apex and surface quite coarsely punctured with sparse rather long whitish setae, in general with longitudinal median area bald and impunctate.
Elytra yellow with suture narrowly black and three pairs of transverse black rounded spots none of which reaching margins or suture and with no tendency to coalesce transversally in the examined specimens. Anterior outer spot covering humerus and placed slightly forward in respect of the inner one. Spots of the second pair lined up. Surface dull with minute rather sparse punctation mostly arranged in almost regular shallow striae, fairly confused only towards median line. Intervals flat.
Surface of pygidium yellow, smooth, covered by sparse weakly impressed small punctures and pale setae.
Inferior parts black with hypomera more or less extensively yellow on sides and an elliptical yellow spot on median part of metathorax. Abdomen black with sides of sternites yellow. Last visible abdominal sternite almost completely yellow with the exception of anal depression which is blackish. All ventral surface covered by scattered whitish rather long setae, regularly distributed except on hypomera and on sides of mesothorax. Punctuation regularly arranged and shallow, coarser on hypomera and sides of metathorax. Prosternal process longitudinally sunken with apex roughly triangular and slightly raised. Prosternal surface covered with long dense pale setae. Legs yellow with tarsi and apex of tibiae black.
Fifth abdominal ventrite with elliptical, shallow, smooth, bald, impunctate median depression and posterior margin fairly notched. Median lobe of aedeagus (Fig. 10 c–e) subcylindrical with surface smooth. Aedeagal apex triangular, fairly bent ventrally, marked by a pair of perceptible lateral thickenings towards base, with hairy dents apparent, minutely wrinkled, bearing few scattered whitish setae. Aedeagal ventral profile fairly bulging below apex in lateral view.
Endophallus (Fig. 10 f–g) with sclerite I well sclerotized, large, with a well-developed, robust, stout denticle placed close to upper rim of sclerite. Dorsal spicule strongly developed, twig-shaped, distinctly bent backwards. Sclerite II quite short, slightly bent at base. Sclerite III rather oblique so poorly projecting upwards, with arch slender and a long tapered apex. Branches of sclerite IV longer than sclerite III in the folded up structure, robust, with rounded, almost symmetrical apex and surface fairly microsculptured.
Female. Habitus in Fig. 10 a–b (LT). BL = 7.2 mm, BW = 4.3 mm, PL = 2.3 mm, PW = 3.4 mm. Interocular distance 14.1% of BL.
Fifth abdominal ventrite in females with a rather shallow, almost circular pit. Spermatheca (Fig. 10h) with lower branch of vasculum straight, evenly thickened. Upper branch swollen on its median part then regularly tapered towards apex, with tip roughly bent downwards. Duct tightly coiled in proximal and median part. Coils looser but apparent also in the last section. Insertion on bursa copulatrix rather protruding, pear-shaped. Rectal apparatus (Fig. 10 k–m) with dorsal sclerites stout, shortly and quite abruptly tapered towards median line and moderately large apodemes. Ventral sclerite deep, lighter on its median part, ribbon-like, tapered on sides, with rather large, protruding apodemes, fringed on rim.
Remarks. Among the fresh specimens used for redescription, the female fits well with the syntypes above all for the colour pattern, the size and the overall habit. The male is slender and quite small, and the pronotal puncturation is fairly more impressed, but it fits rather well with the syntypes for the pronotal shape and the very similar, and not observed in any other species, pronotal color pattern.
McFayden (1987) reported this species from Brazil and gave some information about its biology. However, Mc Fayden relied on Monrós to identify the material, and the only specimen labelled as M. patagonicus in Monrós's collection at the USNMNH is indeed a M. albipes. For this reason, I am inclined to assume McFayden's material to have been wrongly identified and it might actually belong to M. albipes. Accordingly, the occurrence of M. patagonicus in Brazil should be confirmed by further data.
description: Published as part of Sassi, Davide, 2018, Revision of the Metallactus kollari species-group with a new diagnosis of the genus (Coleoptera: Chrysomelidae: Cryptocephalinae), pp. 57-110 in Zootaxa 4413 (1) on pages 83-86, DOI: 10.11646/zootaxa.4413.1.2, http://zenodo.org/record/3066636