Chanealtica, Konstantinov, Alexander S., 2016

Konstantinov, Alexander S., 2016, Possible living fossil in Bolivia: A new genus of flea beetles with modified hind legs (Coleoptera, Chrysomelidae, Galerucinae, Alticini), ZooKeys 592, pp. 103-120 : 105-106

Taxon classification Animalia Coleoptera Chrysomelidae

Chanealtica gen. n. Figs 1-5, 6-10, 11-12, 13-18, 19-25, 26, 27-31, 32-36

Description.

Body length: 2.59-3.29 mm; body width (widest point of elytra): 1.35-1.67 mm. Pronotum width to length ratio: 1.66-1.77. Width of elytra at base (in middle of humeral calli) to width of pronotum at base ratio: 1.20-1.21.

Body light ochre with last eight antennomeres, elytral apices (in Chanealtica cuevas ) and bases of metatibia dark brown.

Head with midcranial and frontal sutures absent. Supraorbital sulcus deep. Orbital sulcus visible, situated close to eye. Supracallinal sulcus absent. Supraantennal sulcus shallow, poorly developed. Midfrontal sulcus developed only dorsally, absent ventrally, antennal calli completely separated only dorsally, connected ventrally. Suprafrontal sulcus poorly developed. Frontolateral sulcus well developed. Antennal callus long, oblique, nearly triangular, entering interantennal space. Surface of antennal callus covered with fine, long, transverse wrinkles, situated slightly above surface of vertex. Vertex densely and evenly covered with deep, but poorly delineated punctures. Frontal ridge and vertex separated by antennal calli. Width of frontal ridge to width of antennal socket (including surrounding ridges) ratio 0.85 - 0.88. Frontal ridge short, in lateral view almost straight. Area below antennal socket concave. Orbit normally wide, nearly as wide as transverse diameter of antennal socket. Distance between eyes above antennal sockets to transverse diameter of eye in frontal view ratio 3.25 - 3.32. Sides of head below eyes converging ventrally. Labrum flat, with 2 pairs of long setae; anterior margin complete, with slight indentation on upper surface. Apical maxillary palpomere conical. Preapical maxillary palpomere wider than apical palpomere. Antennal sockets situated below middle of eye. Antenna filiform, with 11 antennomeres. Length of antenna over pronotum reaching beyond middle of elytron.

Pronotum wider than long, with sides slightly convex to nearly straight. Pronotal base slanted from posterolateral callosities, straight in middle. Lateral margin narrowly explanate, without setae. Anterolateral callosity relatively short, nearly perpendicular to lateral margin. Posterolateral callosity short, not protruding beyond lateral margin. Pronotal punctures relatively dense, shallow. Procoxal cavities open. Intercoxal prosternal process short, narrowing posteriorly, does not extend beyond procoxae, lateral sides straight, posterior end rounded.

Scutellum present. Elytron with punctation confused and few irregular poorly defined longitudinal ridges. Elytra at base wider than base of pronotum. Humeral calli well developed. Basal calli present, poorly separated from elytral disc. Epipleura slightly oblique outwardly, gradually narrowing from base to apex, reaching end of elytron side, but not apex. Mesosternum without elevated projection in middle, flat, in shape similar to intercoxal prosternal process. Metasternum anteriorly without elevated projection in middle and not projecting forward hiding mesosternum.

First adominal ventrite free. Abdominal ventrites about equally long. First abdominal ventrite between coxae without longitudinal ridges, with apex truncate. Last visible tergite without longitudinal groove in middle. Male last abdominal sternite with transverse ridge. In female ridge absent, instead last abdominal sternite forms posteriorly directed lobe with slightly converging sides.

Pro- and mesotibiae canaliculate dorsally. Protibial and mesotibial spurs absent. Metatibia strongly curved. Metatibia in cross section around its middle more or less triangular. Dorsal surface flat to concave. Bristles present on lateral and mesal sides of metatibiae. Metatarsomere 1 attached away from metatibial apex, distance between metatarsal attachment and metatibial apex about 0.3 of metatibial length. Apical spur of metatibia simple, wide, ending in one tooth, situated in middle, but directed medially. Metatarsomere 1 nearly round, longer than rest of metarsomeres together. Claws appendiculate.

Median lobe of aedeagus in cross section somewhat flat, with shallow impressions near apex.

Spermatheca with distinct border between receptacle and pump. Receptacle slightly longer than wide, much wider but about as long as pump, ovoid. Spermathecal duct very wide at base, curved, without coils. Vaginal palpi not fused medially, gradually narrowing posteriorly with a few bristles at apex. Tignum with narrow and relatively short base and wide and long sclerotization posterior.

Etymology.

I named the genus after the Chané, a native ethnic group of people, whose traditional lands are in the plains and valleys between the Gran Chaco and the Andes in Bolivia and also in northern Argentina and Paraguay. The name is feminine.

Type species.

Chanealtica cuevas Konstantinov, sp. n.

Host plant.

Tecoma stans (L.) Juss. ( Bignoniaceae ) (Figs 11, 12).

Remarks.

Chanealtica is markedly different from most known flea beetle genera. However, based on the general structure of the hind tibia and tarsi, Chanealtica is similar to extant Aphthonoides , Argopistes , Metroserrapha , Psylliodes , and extinct Psyllototus . Representatives of all these genera have their metatarsi attached not at the apex of the metatibia but before the apex (Figs 37-42). Many flea beetles of the subtribe Monoplatina have their metatarsi attached to the metatibia before its apex, but the distance from the place of the attachment to the apex is very short in Monoplatina compared to that of Aphthonoides , Argopistes , Chanealtica , Metroserrapha , Psylliodes , and Psyllototus . In addition Monoplatina are clearly different based on a number of phylogenetically important characters (such as globose fourth meso- and metatarsomere, densely setose dorsal surface of the body etc.).

Chanealtica can be easily separated from Aphthonoides based on a much larger size, metatibia much longer than metatibial spur, confused elytral punctures and numerous features of the head and thorax ( Aphthonoides has much smaller body, metatibia much shorter than metatibial spur, elytral punctures arranged into striae). Chanealtica clearly differs from Argopistes in having an elongate and flat body in lateral view, prognathous head, short frontal ridge, narrow and oblique outwardly elytral epipleura (in Argopistes body round and convex in lateral view, head opistognathous, frontal ridge long, elytral epipleura wide and oblique inwardly).

In the site of the metatarsal attachment and general shape, metatibia of Chanealtica is more similar to that of Metroserrapha and Psylliodes . In these genera, the metatarsi are attached at about basal 2/3 of the metatibia; the dorsal surface of the metatibia before the metatarsal attachment is flat or canaliculate with lateral margins lacking denticles; the dorsal surface posterior to the metatarsus is deeply channeled and lateral margins are covered with denticles or a row of stiff and short bristles; the metatibial apex is armed with a large, acute spur. Chanealtica can be easily distinguished from Metroserrapha and Psylliodes based on a large body flat in lateral view, confused elytral punctuation, short frontal ridge, anterolateral callosity relatively short, nearly perpendicular to lateral margin of pronotum. In addition, Chanealtica and Metroserrapha species have 11 antennomeres while all Psylliodes species have 10.

The last abdominal sternite contains the unique feature of Chanealtica . In male the apex of the sternite is swollen into a transverse ridge. In female the ridge is absent, instead the last abdominal sternite forms a posteriorly directed lobe, which is common in males of many other flea beetle genera (e.g. Longitarsus Berthold).

Based on the characters that are available for observation in amber preserved specimens, among all the flea beetles, Chanealtica is mostly similar to an extinct genus Psyllototus . They share two most vivid character states: structure of the hind leg and antennae with 11 antennomeres. Details of Psyllototus head and ventral side of the body are not available for study.