Indolestes gracilis subsp. expressior Kosterin 2015
Creators: name: Kosterin, O. E.
Publisher: name: Zenodo
Year: 2015
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Odonata
Lestidae
Indolestes
Indolestes gracilis
Indolestes gracilis expressior ssp. nov.

description: Indolestes <i>gracilis</i>expressiorssp. nov. Figure 4 a-h <b>Material</b> studied Holotype <b>&amp;male;</b>, Cambodia, Mondulkiri Province, the river upstream Buu Sraa Waterfall, the left bank at the bridge, 12°33'55'' N 107°25'09'' E, 502 m a.s.l., 9 VI 2014; deposited in Naturalis Biodiversity Centre, Leiden, the Netherlands (RMNH). Etymology <i>Expressions</i> a Latin <i>adjective</i> in gradus comparativus and genus masculinus, meaning ‘more expressed', referring to a more expressed differentiation of the apical part of the cercus than in other subspecies. Male (Figure 4) Head. Labium bluish in central part, yellowish at margins. Labrum, mandible bases, genae dull bluish (Figure 4a, b). Anteclypeus of the same colour with a small indistinct dark spot at centre, postclypeus mostly dark-bronze with anterior part dull bluish forming a central projection of this colour. Frons, vertex and occiput dark-bronze, there is a pair of greenish spots just below lateral ocelli and another one lateroposteriorly of the former. Antennae blackish-brown (Figure 4b). Thorax. Prothorax dull bluish with dorsal suture slightly darker brown and a pair of two indistinct bronze dorso-lateral patches (Figure 4c). Posterior lobe slightly raised with smooth margins, light-brown, darker dorsally (Figure 4a, c). Mesostigmal plate broadly-triangular, with a transversal lens-shaped central hollow deepening to its lateral ends, and deep middorsal groove. Central hollow and adjacent anterior margin brown, the rest dark-bronze but with brownish lightenings at sides of middorsal groove (Figure 4c). Synthorax ground colour changes from olivaceus at mesepisternum to dull blue on sides (Figure 4a). There is a broad middorsal dark-bronze band but dorsal ridge narrowly brown. <i>There</i> are elongate black spots at top of humeral and the first lateral sutures and a slight trace of a brownish stripe below mesopleural suture, with a small brown spot with indistinct margins in its dorsal part (Figure 4d). Sclerites at wing bases blue. Coxae and trochanters bluish, rest legs brownish, with outer sides of femora, ventral ribs of tibia, tips of tarsi, spines and hooks blackish (Figure 4a). <i>Wings</i> hyaline, major veins dark brown, minor ones black. Discoidal cell very narrow, its dorsal side is ca 0.35 as long as ventral side in fw and ca half as long on hw postnodals 10 on fw, 9 on hw. Pterostigmata of folded fore and hind <i>wings</i> disposed exactly near each other. They are ca 2.2 as long as high, accompanied with two cells below, dark-brown, bordering longitudinal veins somewhat swollen and darkened (Figure 4e). Abdomen. Ground colour dull blue at S1-S3 (Figure 4a) changing to brownish at S5- S8 (partly shown in Figure 4f) but <i>again</i> greyish blue at S9-S10 (Figure 4g, h). Tergites 1-7 with solid dark-bronze to blackish dorsal <i>stripes</i>.That on S2 shaped as squid body with a tail directed anteriorly. Those on S2-S7 are constricted anteriorly, before tergite anterior margins, marked with black rings, and rather indistinctly expanding to tergite ventral margins posteriorly (Figure 4a, f). S8 dark with indistinct lateral brownish patches in its anterior half (Figure 4f). S9 blackish with a pair of indistinct greyish-blue spots at posterior margin, nearly fused to each other, occupying half of its length. S10 greyish blue above changing through reddish-brown to blackish below (Figure 4h). Cerci about twice as long as S10. In dorsal view (Figure 4h), their outer outline (bearing sparse robust spines) smoothly curving towards each other to distinct apical portions occupying about 1/3 of the cercus projection to the central <i>axis</i>. Apical portions dropshaped, rounded proximally, bluntly pointed distally, directed caudally but very slightly diverging. Inner outline of cerci elaborate: narrowing at ca 1/5 of their length, then with a ventro-adaxial ledge ending with a long process, then slightly broadening again; cercus apical portion forms a prominent rounded backward ‘heel'. In lateral view (Figure 4g), cercus dorsal outline nearly straight at basal 2/3 then bends down. Cercus ventral outline narrowing at basal 1/4, ventro-adaxial ledge with a subbasal blunt spine (not seen in dorsal view) and apical process; cercus apical portion hoof- or pen-like, with a rounded base and attenuated apex, occupies 1/3 of cercus length. Cercus dorsal side greyish blue,apical portion blackish-brown,rest brown (Figure 4g,h). Paraprocts light-brown, thrice as short as <i>cerci</i>, rounded in dorsal <i>view</i>, trapezoid in lateral <i>view</i>, their dorsolateral side deeply concave with semicircular ridges occupying the concavities (Figure 4g, h). Measurements [mm] - hw 18; abd (without apps) 29; total length (with apps) 38. Female unknown Differential diagnosis and remarks The shape of the cerci of the new subspecies (Figure 4h) <i>is</i> close to that of <i>I. gracilis</i> spp. (Figure 1 b-e) and <i>I. peregrinus</i> (Figure 2). However, the apical portion of the cerci <i>is</i> curiously inflated basally in dorsal view, forming a prominent ‘heel' protruding medio-anteriorly. So the cerci resemble rather legs and feet of a man in the act of brass swimming than the arms and hands of a man in the act of <i>diving</i>, as in the mentioned species. None of so far described taxa of Indolestes displays this shape of the cercus apical part, modification of which in the new subspecies looks most pronounced as compared to the related taxa. In other subspecies of <i>I. gracilis, I. peregrinus</i> and <i>I.</i> <b>cyaneus</b>, the inner outline of the cercus at the apical portion base in dorsal view just turns caudad without a concavity before the apical part to form the ‘heel'. Drawings of the appendages of <i>I. gracilis</i> spp and <i>I. peregrinus</i> from Ris (1916), Fraser (1933) and Asahina (1976) are reproduced in Figures 1 b-e + 2a-c. Indolestes <b>cyaneus</b> has more robust cerci with a less attenuated and inflated apical part (Figure 1a) (Fraser 1933). The coloration of the cerci, with distinctly darker apical portion, <i>is</i> as in <i> <i>I</i>. peregrinus</i> (Asahina 1976), while in <i>I. gracilis</i> gracilis they are almost dark throughout (Fraser 1933; Asahina 1976). However this character may vary with age, individually and geographically. The paraprocts in /. <i>gracilis expressior</i> ssp. nov. (Figure 4h) are bluntly rounded in dorsal view, as should be in <i> <i>I</i>. gracilis.</i> The body coloration and pattern, with straight margins of the synthorax median black band and the solid abdominal black markings not divided into anterior/posterior or left/ <i>right</i> parts, <i>is</i> similar to those in <i>I. gracilis</i> and contrasted to <i>I. peregrinus</i> (Asahina 1976). Moreover, reduction of the humeral spots is similar to the nominotypical subspecies <i>I.</i> g. gracilis from Sri Lanka. Lieftinck (1940) pointed that in that subspecies, these spots are variable from complete absence to 3-4 isolated spots or even fused into irregular fascia (as in <i>I.</i> g. davenporti and <i>I.</i> birmanus <i>).</i> The small spot below the mesopleural suture in the holotype of <i> <i>I</i>. gracilis expressior</i> ssp. nov. (Figure 4d) <i>is</i> brown and diffuse at margins, as it often happens with a variable, environmentally induced melanisation in some damselflies, e.g. in northern populations of <b>Enallagma</b> cyathigerum Charpentier, 1840 in Eurasia (Kosterin &amp; Zaika 2010). <i>Yokoi</i> &amp; Souphanthong (2014: fig. 4) provided a drawing of the appendages of a male of « lndolestes sp. 3» (Figure 5) from Paksong, Bolaven Plateau, Champasak Province, southern Laos. Their shape <i>is</i> very similar to <i>I. <i>gracilis expressior</i> ssp. nov., so that specimen most probably represents the same subspecies. Unlike the here described holotype, the photo of the general habitus of this specimen shows a complete humeral <i>stripe</i> (Ibid.: pl. 1). However, the great variation of the humeral pattern is common in Sympecmatinae and observed in <i>I. gracilis gracilis</i> (Lieftinck, 1940), hence <i>is</i> expected in Indolestes <i>gracilis expressior</i> as well, perhaps depending on environmental conditions.</i> Distribution The subspecies <i>is</i> known from eastern Cambodia and (tentatively) southern Laos. Habitat The holotype was startled from a bush branch in a secondary growth at the left bank of the large river which form the well-known Buu Sraa Waterfall. There were also some shallow stagnant pond and pools nearby. This place was at 502 m a.s.l. (as to Google Earth) and was surrounded by countryside but close to the evergreen forest in the river valley downstream of that place. The Laotian male presumably of this new subspecies was collected at 1310 m a.s.l. (Yokoi &amp; Souphanthong 2014).The nominotypical Sri Lankan subspecies inhabits mountains, with localities between 1800 and 2500 m a.s.l. (Bedjanic et al. 2014: 76-77).
description: Published as part of <i>Kosterin, O. E., 2015, Taxonomical notes on Indolestes Fraser, 1922 (Lestidae, Zygoptera). 1. Indolestes gracilis expressior ssp. nov. from eastern Cambodia, pp. 1-11 in IDF-Report 81</i> on pages 5-9, DOI: 10.5281/zenodo.3358796
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