Research Article |
Corresponding author: Shawn M. Clark ( shawn_clark@byu.edu ) Academic editor: Alexander Konstantinov
© 2020 Keezhpattillam Viswajyothi, Shawn M. Clark.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Viswajyothi K, Clark SM (2020) Prathapanius fortis, a new genus and new species of Galerucinae from Ecuador (Coleoptera, Chrysomelidae). ZooKeys 968: 111-126. https://doi.org/10.3897/zookeys.968.54228
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Prathapanius Viswajyothi & Clark, gen. nov., is described and illustrated. The genus is placed in the chrysomelid section Diabroticites Chapuis (subtribe Diabroticina Chapuis, tribe Luperini Chapuis, subfamily Galerucinae Latreille). It is monobasic, containing Prathapanius fortis Viswajyothi & Clark, sp. nov., from Ecuador. The new genus is briefly compared with Acalymma Barber, Isotes Weise, and Zischkaita Bechyné.
Diabroticina, Diabroticites, leaf beetles, Luperini, Neotropics, sexual dimorphism
Over the last half century, the prevailing classification of the chrysomelid subfamily Galerucinae Latreille has largely followed the catalogues of
In the present study, we follow a middle-of-road approach, provisionally accepting the combining of Alticinae with Galerucinae, but retaining all the tribes of the former Galerucinae at tribal rank. This approach was also followed in works such as by
Following
Phylogenetic studies do not entirely support the above classification, even at the level of tribe (
In anticipation of the eventual publication of a key to the New World genera of Galerucinae (exclusive of Alticini), we have examined examples of nearly every genus of the subtribe Diabroticina. Beyond studying authoritative determined material, we have also attempted identification of many thousands of previously unidentified specimens. We discovered specimens that clearly do not match any of the described genera, and we herein propose a new genus to accommodate them. The single included species has remarkably modified legs in the male.
Strange morphological modifications are common in the chrysomelid subfamily Galerucinae. Although some are present in females, most are secondary sexual characters present only in males. They involve the head, antennae, pronotum, elytra, legs, etc. In many instances, their function is unknown. However, some of them may be related to mate recognition, pheromone dispersal and detection, sound production, or grasping during mating (
All specimens studied were adults. Genitalia extractions and preservation largely followed the methodology described by
Specimens are deposited in the Monte L. Bean Life Science Museum, Brigham Young University (Provo, Utah, U.S.A.;
This genus is easily recognized by the remarkable male characters. The front femora are enormously enlarged (Figs
Using the key to genera by
Body narrow, oblong (Fig.
The name of this new genus honors K. D. Prathapan, renowned chrysomelid systematist and advisor to the senior author. The enormous front femora of the males are comparable to the strong personality and scientific prowess of Dr Prathapan. The genus name should be treated as a masculine noun.
This genus clearly belongs in the galerucine section Diabroticites (Luperini, Diabroticina), as evidenced by the absence of basal spurs on the aedeagus, the absence of a rectangular lobe at the apex of the male abdomen, and the presence of bifid tarsal claws. However, the relationships within this section are debatable. The short setae along the lateral margin of the pronotum, as well as the longer setae on the elytral disc, suggest a relationship to Acalymma Barber and Zischkaita Bechyné. However, these genera have short genae. The large genae of Prathapanius suggest a relationship with Isotes. This is reinforced by the fact that some (but not all) species of Isotes have a small keel on the aedeagus, although not nearly as large as the dorsal fin of Prathapanius (
This new genus currently includes a single species. However, future investigation may prove that Zischkaita serrana Moura also belongs here, although it is a much less slender beetle. The male front legs of Z. serrana exhibit modifications very similar to those of Prathapanius, except that the femoral enlargement is not nearly as dramatic (
Body narrow, oblong, 5.1 mm long, 1.6 mm wide (Fig.
Vertex
black; antennal calli, frontal ridge, and anterofrontal region entirely pale (Figs
Antennae slender, filiform, extending to about middle of elytra, entirely covered with short setae, with a few longer setae present. Basal antennomere entirely pale yellow; second and third antennomeres pale yellow ventrally, dark brown dorsally; fourth through eleventh antennomeres dark brown. First antennomere widest, inflated, club-shaped; length ratios of antennomeres (comparisons to antennomere 1): 1.0, 0.5, 1.0, 1.3, 1.1, 1.0, 0.8, 0.8, 0.8, 0.7, 0.8; length to width ratios: 2.5, 2.5, 5.0, 7.0, 5.5, 5.5, 5.5, 4.5, 4.0, 4.0, 4.5; distal conical portion of eleventh antennomere separated by shallow groove, giving false appearance of additional antennomere.
Labrum
semicircular, nearly twice as wide as long, with anterior margin almost entire; color brownish black; six setae present, arranged in transverse row, three on either side of middle, arising from basal third of labrum, extending slightly beyond distal margin; distal margin with a few additional, minute setae, arranged in transverse row. Mandibles brown, tridentate, slightly exposed beyond edges of labrum in anterior aspect. Maxillary palpi pale, slender, with setae arising laterally; penultimate palpomere more setose than others, largest in length and width (Figs
Pronotum entirely pale; shape nearly quadrate, slightly wider just anterior to middle, with slightly sinuate lateral margins; greatest width 1.3 times more than that of head across eyes; surface glabrous, shiny, alutaceous, obsoletely punctate, with scattered punctures on disc visible only on close examination; distinct mesal depression present in basal half; lateral bead equipped with short setae along entire length; anterolateral seta-bearing pore obtusely angulate; posterolateral seta-bearing pore acutely angulate. Scutellum black, glabrous, impunctate, shiny, with alutaceous microsculpture.
Elytra
black, with lateral areas and epipleura uniformly pale (Fig.
Ventral
areas of prothorax pale, glabrous (Figs
Legs
mostly pale (Fig.
Median lobe of aedeagus (dorsal aspect) broad in distal tenth, shallowly incised at distal tenth, gradually narrowing from behind incisure to near mid-length (at mid-length, 0.6 times maximum width), slightly broadening from mid-length towards base; apex truncate in dorsal aspect, with small, median, knob-like projection (Fig.
The body varies from 4.8 to 5.6 mm long. The head may be almost entirely pale, with only a small brown marking on the posteromedial area of the vertex. This varies to an almost entirely black head, with only parts of the antennal calli and anterofrontal region pale. In some specimens, the region below the eyes and the antennal fossae are pale, while the frontal ridge and anterofrontal ridge are brownish black. In others, the frontal ridge is pale, the antennal calli and the entire area beyond the eyes and antennal fossae are brown, while the rest of the head is black. In some specimens, the dorsal surface of basal antennomere is distally or entirely brown. Rather than entirely pale, the pronotum may have a brownish black, irregularly shaped macula (Fig.
Although lacking the odd modifications of the legs, females are much like males. The antennomere length ratios are 1.0, 0.6, 1.0, 1.5, 1.1, 1.1, 1.0, 0.8, 0.8, 0.8, and 1.0. The length to width ratios are 2.5, 2.3, 3.0, 5.5, 4.3, 4.3, 3.8, 3.0, 3.0, 3.0, and 3.8. The female pronotum is almost evenly convex, but, upon close examination, two semicircular, very shallow depressions are noticeable, one on either side of the meson, near the mid-length of the disc. The front trochanter lacks a spine; the front femora are not unusually enlarged, but instead are more slender than the hind femora and only slightly broader than the middle femora; the pro- and metatibiae are similar to those of the middle legs; and the hind femora are not abnormally enlarged. Tiny tibial spurs are present on all legs (on only the middle legs of males). In the front legs of females, the basitarsus is slightly longer than and about as wide as the second tarsomere. In the middle legs, the basitarsus is 1.5 times longer than and the same width as the second tarsomere. The tarsal setation is the same in all three pairs of legs, the basitarsi of the front and middle legs are lacking adhesive pads. The posterior margin of last ventrite is entire (Fig.
The bursa copulatrix is adorned with a carina and sclerotized patches (Fig.
“Ecuador:GuayasProv. \ Salanguillo 90 m. \ 19 FEB 1987 \ K. A. Johnson colr.” [1°58'S, 80°34'W, coordinates estimated, not included on label] (male,
Same data as holotype (4 females,
The species epithet, fortis, is Latin for strong, mighty, or powerful. It is in reference to the enormous front femora of the male.
This species occurs in a seasonally dry forest, near sea level, near the Pacific coast of Ecuador (Fig.
In addition to the remarkable modifications of the male front legs, the male genitalia are also extraordinary, with fin-like structures on both the median lobe and tegmen. Before the soft tissues were removed, the basal portion of the aedeagus was heavily surrounded by muscle tissue, somewhat similar to the condition found in the subfamilies Eumolpinae and Cryptocephalinae.
We thank R. Wills Flowers for supplying the photograph of the area near the type locality. We appreciate the support of the Kerala Agricultural University and Brigham Young University. We are especially grateful to the Fulbright-Nehru Doctoral Research Fellowship Program that provided funding to the senior author while visiting in the United States.