Leptobasis Selys 1877
Creators: name: Garrison, Rosser W.
name: Ellenrieder, Natalia Von
Publisher: name: Zenodo
Year: 2010
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Odonata
Coenagrionidae
Leptobasis

description: Leptobasis Selys 1877
Leptobasis Hagen in Selys 1877: 99 (5 reprint). = Hylaeagrion Förster 1906: 15.
Type species: Agrion croceum: Förster 1906 (nec Burmeister 1839), subsequently designated by Williamson 1917.
(Note: All catalogs (Davies & Tobin 1984: 78; Bridges 1994: III.22, Steinmann 1997: 290; Tsuda 2000: 208) treat Hylaeagrion as a synonym of Aeolagrion Williamson 1917 with its type species H. argenteolineatum Förster 1906 (= Agrion dorsale Burmeister 1839). Förster described Hylaeagrion including two species, " Leptagrion? croceum Selys-Burmeister " and Hylaeagrion argenteolineatum (sp. nov.) both from Surinam; he did not designate a type species. Williamson (1917: 241) considered Leptagrion croceum (= Agrion croceum Burmeister 1839) as type species ("The second new genus proposed by Foerster is Hylaeagrion, of which Leptagrion croceum, of his determination must be the type, congeneric with which, according to Foerster, is his new H. argenteolineatum, known from the male only…"). From Förster's description, Williamson believed Leptagrion croceum Förster (nec Burmeister) to be a Leptobasis —probably L. vacillans —based on illustrations of Burmeister's type of Agrion croceum.)
= Chrysobasis Rácenis 1959: 55 (description, type species Chrysobasis buchholzi Rácenis 1959 by original designation) syn. nov.
Type species. Leptobasis vacillans Hagen in Selys 1877, subsequently designated by Kirby (1890).
Other species included. Leptobasis buchholzi (Rácenis 1959) comb. nov., L. candelaria Alayo 1968, L. guanacaste Paulson 2009, L. lucifer (Donnelly 1967) comb. nov., L. mauffrayi Garrison & von Ellenrieder 2009 sp. nov., L. melinogaster González-Soriano 2002, L. raineyi (Williamson 1915).
Calvert (1909) described Leptobasis mammilaris based on two males (one incomplete) from Chapada, Brazil, and a female (Rio de Janeiro) which he doubtfully assigned to this species. Machado (2009) transferred L. mammilaris to his new genus Tuberculobasis, and Williamson (1917) and Garrison (in Machado 2009) both expressed doubt as to the identity of Calvert's female. Our examination of the female from Rio de Janeiro shows it to be a female Telagrion longum Selys.
Synonymy of Chrysobasis. Of the characters proposed for Chrysobasis (Rácenis 1959), an equally short CuA is found in Leptobasis candelaria, L. guanacaste, L. melinogaster, L. raineyi, and often in L. vacillans. A short ventro-basal process is present on the cercus of C. buchholzi (Fig. 20 a), which we observed similarly developed in C. lucifer, L. candelaria, L. guanacaste, and L. melinogaster (Figs. 20 b–d, f), reduced to a very low bump in L. mauffrayi, L. raineyi, and L. vacillans (Figs. 20 e, g–h). The pair of lobe-like processes on sides of medial cleft of postero-dorsal margin of male S10 described by Rácenis (1959) for C. buchholzi (Figs. 20 a, 21a) is present also, although less developed, in C. lucifer (Figs. 20 d, 21d), and even less developed in L. melinogaster (Figs. 20 f, 21f). Thus, none of these three characters, and no other combination of characters, can be employed to confidently diagnose two genera within this complex of species. Moreover, these eight species share a unique genital ligula morphology within Coenagrionidae, indicating their close relationship: the distal segment has a pair of chitinized, flap-like, movable processes directed posteriorly (shared only with the nearctic genus Hesperagrion Calvert, Figs. 9–17), an inner fold proximal to ligula flexure (absent in Hesperagrion, which has a transverse fold distal to ligula flexure; see discussion), and no lateral lobes. For all these reasons we consider Chrysobasis a junior synonym of Leptobasis.
Characterization. Small to medium coenagrionids (26–41 mm), with a relatively long abdomen (ratio of 4–5.25 to length of head plus thorax); dorsum of head, thorax, and S3–8 black, brown, or orange; pterothoracic stripes blue or green, S7–10 to S9–10 blue, yellowish, orange, reddish, or black; pale areas on sides of thorax and abdomen yellow and green (Figs. 23–26). Pale postocular spots and pale occipital bar present (Figs. 1 a, b, d), blue or green, or absent (Figs. 1 c, 26d). Frons rounded; location of most posterior point of head at level of eyes. Posterior lobe of prothorax smoothly convex, bi- or trilobate, projected medially or not projected in both sexes (Figs. 2, 4). Pterothorax with (Figs. 24 a, 26a) or without (Figs. 26 b-d) dark middorsal and humeral stripes; dark metapleural stripe absent; pale antehumeral stripe present and mesepimeron and metepisternum mostly pale; pterothorax entirely orange in immature specimens (Fig. 26 d). Female lacking well defined mesepisternal carinae between mesostigmal plates and medial carina (Figs. 3 b–e). Metatibial spurs shorter than twice intervening spaces (Fig. 5 c); pretarsus with supplementary tooth very small, forming a right angle with claw. CuA extending 2–6 cells distal to vein descending from subnodus (Figs. 6–8), occasionally 7–8 in L. vacillans; CuP linking CuA to posterior wing margin (Figs. 6–8). Genital ligula distal segment with inner fold proximal to flexure; lacking lateral lobes; with apex entire to bifid; with a lateral chitinized flap-like process distal to flexure directed posteriorly on each side (Figs. 9–16). Posterodorsal margin of male S10 with (Figs. 21 a, d, f) or without (Figs. 21 b, c, e, g–h) a pair of lobe-like processes on sides of medial cleft. Male cercus shorter than or subequal to S10, with a short ventro-basal branch on medial surface; male paraproct entire and shorter to longer than cercus (Fig. 21). Female usually lacking a vulvar spine on S8 (Figs. 19 a–e), although a small spine is present in most females of L. vacillans (Fig. 19 f); postero-dorsal margin of female S9 with denticles; ovipositor extending distally to tip of cerci (Figs. 19, 23 b, 24b, 25a, c, 26c, d).
Diagnosis. Leptobasis shares the combination of a rounded frons, CuP reaching hind margin of wing, CuA relatively short, and supplementary pretarsal claw vestigial or reduced and forming a right angle with claw with Dolonagrion Garrison & von Ellenrieder 2008, Mesoleptobasis Sjöstedt 1918, and Telagrion Selys 1876. It differs from all of them by the presence on the distal segment of the genital ligula of a pair of chitinized, flap-like, movable processes directed posteriorly (Figs. 9–16). Branched male cerci lacking a transverse membranous dorsal depression (Figs. 20, 22), and tip of female ovipositor extending distally to postero-dorsal margin of S10 for a distance shorter than length of S10 (Fig. 19), further distinguish it from Dolonagrion, which has entire cerci with a membranous dorsal depression and ovipositor surpassing tip of cerci for a distance longer than S10 length (Garrison & von Ellenrieder 2008). It further differs from Mesoleptobasis in that the vein descending from the quadrangle does not form a straight line to wing margin (Figs. 6–8), versus forming a straight line in the latter (Garrison & von Ellenrieder 2009). Leptobasis differs from Telagrion by the absence of paired ental medio-longitudinal ridges and of an outer-lateral patch of thin setae on the distal segment of the genital ligula (Figs. 9–16), which are present in the latter (see von Ellenrieder & Garrison 2008), and inner margin of female cerci straight or convex in dorsal view, versus concave in the latter.
Distribution. Leptobasis occurs from southern Texas (USA), the Antilles, and Central America south through Venezuela and into southern Peru (Figs. 27–28).
Biology. Adults perch in shady areas on littoral vegetation, grasses or sedges, along margins of ponds, lakes, swamps, and marshes, banks of rivers, and temporary streams; they are rarely seen flying over open water. Daigle (2009) reported L. lucifer flying around fern patches among cypress trees in swamps, with males perching on vines and leaf tips, and females ovipositing in the stem of Lycopus rubellus. The only larva described so far is that of L. vacillans (Geijskes 1941, Needham 1941) although Paulson (2009b) reared L. guanacaste and provided diagnostic differences between the two.
Adults of Leptobasis undergo ontogenetic changes in color and pattern; tenerals and immatures are often pale orange (with a dark mid-dorsal stripe in L. guanacaste) and, in some species, may develop dark middorsal (L. guanacaste) and humeral thoracic stripes against a pale green to orange background (L. buchholzi, L. candelaria, L. lucifer, L. mauffrayi, L. melinogaster, L. vacillans). In L. raineyi these stripes are represented as orange against a pale blue background, but a similar pattern can exist in other Leptobasis species mentioned above. The dynamics of these color changes are not understood and these differences led Calvert (1902, 1909) to apply three varietal names to L. vacillans. Paulson (2009a) suggests that immature colored adults may span the dry season in the tropics; he found adults and larvae of L. guanacaste at temporary pools in Costa Rica during the wet season, and observed mature and immature-colored females in pairs.
description: Published as part of Garrison, Rosser W. & Ellenrieder, Natalia Von, 2010, Redefinition of Leptobasis Selys with the synonymy of Chrysobasis Rácenis and description of L. mauffrayi sp. nov. from Peru (Odonata: Coenagrionidae), pp. 1-36 in Zootaxa 2438 on pages 3-4, DOI: 10.5281/zenodo.194870