Heterochele Viswajyothi and Clark 2021, gen. nov.
Creators: name: Viswajyothi, Keezhpattillam
name: Clark, Shawn M.
Publisher: name: Zenodo
Year: 2021
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Chrysomelidae
Heterochele

description: Heterochele Viswajyothi and Clark, gen. nov.   
(Figures 1–7)  
 Diagnosis   
 Superficially, this genus resembles small (2.7–3.9 mm long) Diabrotica Chevrolat or Acalymma Barber. However, males can easily be distinguished from either of these genera by the deep impression on the last abdominal ventrite (Figures 2 (b, (6d))). Females can easily be distinguished by the appendiculate (rather than bifid) tarsal claws.   
 In the key to genera of Phyllecthrites provided by Moura (2010), males would key to Parabrotica Bechyné and Bechyné (couplet 4), but Heterochele differ from the genus Parabrotica in having the above-mentioned abdominal impression. Moreover, the mesotibial concavity of Heterochele is shallow and rather indistinct (Figure 1 (c), 4(b), 5(a)). Females would key to couplet 9, at which point the user would be frustrated, since males are needed to proceed further in the key.   
 Description   
Antennal fossae positioned near mid-level of eye. Terminal maxillary palpomere as long as or slightly longer than broad, trianglar, evenly narrowed from base to acute apex. Anterior edge of pronotum lacking bead or fringe of setae; lateral carina of pronotum well developed, with sparse fringe of setae (easily rubbed off and sometimes difficult to see); posterior pronotal edge lacking fringe of setae, with poorly developed bead laterally, without bead mesally. Elytral disc with long, suberect, posteriorly inclined setae (Figure 4 (a,b)); majority of setae arranged in five or six longitudinal rows, one along epipleural ridge, one near sutural margin, others in between; a few setae scattered outside of rows; basal half of epipleuron narrow, nearly vertical; distal half of epipleuron extremely narrow, nearly attaining elytral apex, obliquely slanted inward in distal half. Procoxae mesally contiguous; procoxal cavities posteriorly open. Mesepimeron and mesepisternum glabrous. Middle tibia of male slightly concave at distal fifth, on side towards femur (Figure 1 (c), 4(b), 5(a)). Male tarsal claws bifid; female claws appendiculate. Male fifth abdominal ventrite with median depression in posterior half; lateral borders of depression steep, forming acute carina (Figures 2 (b), Figures 6 (d)). Aedeagus asymmetrical; basal spurs absent.  
 Type species   
 Heterochele actias Viswajyothi and Clark, sp. nov.   
 Etymology   
 The genus name, Heterochele, is Greek for ‘different claws’. It refers to the sexually dimorphic tarsal claws. The name is a female noun.   
 Comments   
 The heterogeneous condition of the tarsal claws (bifid in males, appendiculate in females) is extremely unusual. However, this is not unprecedented among the Galerucinae. For instance, Hyperbrotica Bechyné and Bechyné also has bifid claws in the male (clearly bifid on the front and middle legs, also bifid but with a slightly broader inner lobe on the hind legs). Like Heterochele, female Hyperbrotica have appendiculate claws. Erynephala Blake and most species of Monoxia LeConte have bifid claws in males and simple claws in females.   
 Tibial spurs were observed on all legs of some of the females of Heterochele. However, they are extremely tiny and difficult to see among the nearby setae. Indeed, they were not seen on some of the other females, although they may have been present. No tibial spurs were detected on any of the males.   
 Based on the absence of basal spurs on the aedeagus, and on the general appearance, Heterochele is tentatively placed in the subtribe Diabroticina of the tribe Luperini. However, the deep depression on the last male ventrite and the strongly asymmetrical aedeagus are anomalous in the subtribe, but they are similar to the condition in some genera of Galerucini. Even if the genus indeed belongs in Diabroticina, the relationship to other genera of the subtribe is debatable. The general appearance of the beetles, including the suberect elytral setae, suggests a relationship to Acalymma (section Diabroticites). In spite of this, we tentatively place Heterochele in the section Phyllecthrites. The concavity of the male mesotibia, although very shallow, supports this placement. Furthermore, the appendiculate claws of the female are congruent with most Phyllecthrites, but not with Diabroticites. Conversely, bifid claws (present in male Heterochele) are unusual in Phyllecthrites, although present in a few genera, such as Deinocladus Blake.
description: Published as part of Viswajyothi, Keezhpattillam & Clark, Shawn M., 2021, A new genus and two new species of Galerucinae from Costa Rica (Coleoptera: Chrysomelidae), pp. 3103-3119 in Journal of Natural History 54 (47 - 48) on pages 3105-3113, DOI: 10.1080/00222933.2021.1890849, http://zenodo.org/record/5406235