Gynacantha dryadula Neiss & Marmels, 2017, sp. nov.
Creators: name: Neiss, Ulisses Gaspar
name: Marmels, Jürg De
Publisher: name: Zenodo
Year: 2017
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Odonata
Aeshnidae
Gynacantha
Gynacantha dryadula

description: Gynacantha dryadula sp. nov.
(Figs. 1–7)
Gynacantha sp. (near tibiata) De Marmels 1992: 65 (mention of a female from southern Venezuela).
Gynacantha sp. von Ellenrieder 2011: 62 (mention of a female from Kwamalasamutu region, Surinam).
Etymology. “Dryás” (Greek, female gender) means nymph of the forest, dryad; “ dryadula ” is a latinized, diminutive form, used here as a noun in apposition, meaning “little wood nymph”.
Specimens examined. (3♂ 2♀, 2 exuviae): Holotype (subteneral, reared, with its larval exuvia): 1♂, BRAZIL, Amazonas State, Manaus, Reserva Florestal Ducke, BR 174-km 26, path to Acará creek (= Igarapé), 02°55’47”S, 59°58’22”W, 70 m elevation, 13.iv.2009 (emerg. from larva on 27.iv.2009, U.G. Neiss leg. (INPA). 1♂ paratype (subteneral, reared, with its larval exuvia): BRAZIL, Amazonas State, Barcelos, Community of Bacuquara, 00°08’49.4”N, 63°09’58.7”W, 80 m elevation, 29.vii.2009 (emerg. from larva 10.viii.2009), C.A.S. Azevedo, R.L. Ferreira-Keppler, N. Hamada, C.T. Monteiro and A.M.O. Pes leg. (INPA); 1♂ paratype (mature, with live color photos), FRENCH GUIANA, Roura County, Kaw Mountain. Amazone Nature Lodge, 04°33’37.01”N, 52°11’20.94”W, 28.ix.2013, C.O. Rasmussen leg. (JJD); 1♀ paratype (mature, with live color photo), VENEZUELA, Amazonas State, upper Mavaca River, 02°02’10”N, 65°06’50”W, 160 m elevation, 14.ii – 06.iii.1989, J. De Marmels leg. (MIZA); 1♀ paratype (mature), SURINAM, Sipaliwini District, Werehpai, forest trail (2°21’46”N, 56°41’53”W, 258 m elevation, 03.ix.2010, N. von Ellenrieder leg. (CSCA).
Description of male holotype (subteneral; for mature life coloration see description of male paratype from French Guiana and Fig. 1a). Head. Pale brown, postfrons crushed. Thorax (Fig. 2 a). Pale brown, humeral and metapleural sutures dark lined laterally. Legs with first femur and tibia dark brown, second and third femora amber, turning almost black towards tip, tibiae black with pale external (dorsal) streak, tarsi dark brown, spines (spurs) black. Wings (Fig. 2 b, c). Hyaline with small, pale yellow basal spot, which does not reach to middle of median space; pterostigma pale brown, covering slightly more than 3 cells. Venation (left/right). No crossvein anterior to first primary antenodal; FW with 25/26 ax, HW with 20/19; FW with 17/17 px, HW with 18/17; t enclosing 6/7 cells in FW, 6/ 6 in HW, first cell always divided; st in FW with 7/8 and in HW with 6/6 crossveins; fork of IR2 enclosing mostly only 2 rows of cells; anal loop with 8/9 cells arranged in three rows; two cell rows between it and hind border of wing. Abdomen. Strongly constricted at level of S3 (Fig. 2 d), dark with pale spots as follows: S1 pale brown in anterior half and with large, pale lateral spot in posterior half; S2 pale laterally, including base of auricle, a pale mediodorsal spot along transverse carina, and pale posterodorsal spot; S3 with large, pale anterolateral spot reaching to transverse carina, otherwise dark with pale mediodorsal and posterodorsal spots and pale mediolateral and posterolateral spots; S4–8 dark with corresponding pale lateral and dorsal spots. Ventral carina of S2 beset with ill-defined, minute spinules; auricle moderately large, beset with 5 denticles. Genital lobe (Fig. 2 f, g) bearing 2/3 denticles, a few scattered denticles present on margin of genital fossa at level of anterior hamuli; spines of anterior lamina straight, pointed and directed ventroposteriorly; anterior hamuli pointed; vesica spermalis as in Figure 2 h. Caudal appendages dark brown, almost black; cercus straight in lateral view, its tip transversely truncate, lacking apical spine; blade beginning to expand at slightly less than a third of length of cercus, its mesal border hairy and only weakly convex; epiproct slightly surpassing half the length of cercus, narrowing gradually toward tip (Fig. 3 a–c).
Dimensions. Total length 51; abdomen 38; cercus 4.5; FW 38.5; HW 37.5; pterostigma (HW) 2.8; hind femur 5.8.
Male paratype from Brazil (subteneral). Similar to holotype, with following wing vein characters: FW with 23/24 ax, HW with 19/20; px in FW 17/17, in HW 17/16; t enclosing 6 cells in all wings; st in FW with 6/5 crossveins, in HW with 5/4; anal loop with 9/7 cells.
Dimensions. Total length 50; abdomen 37; cercus 4.9; FW with tips damaged; HW 38; pterostigma (HW) 2.9; hind femur 5.8;
Male paratype from French Guiana (mature). Live coloration (Fig. 1a): Head. T-spot well-developed, but with stem lighter brown than brown black transverse bar and connected with dark basal band, which does not descend laterally on postfrons; face green with some yellow on postclypeus, labrum and mandibles; frontoclypeal suture finely lined brown; compound eye blue anterodorsally and green below and laterally. Thorax. Pterothorax bright green with black median carina and incomplete, dark brown mesepisternal stripe which is arched mesad in upper half and fades out apically; humeral and metapleural sutures lined with dark brown, interpleural suture with short, brown marks, the largest at upper end of suture. Wings. Hyaline with pale yellow basal spot, as holotype; venation black, wing membrane very weakly tinged with brown in costal area and along hind border of HW; pterostigma brown dorsally. Legs. Femora reddish brown at base, rest of legs and tarsi black, except for yellow streak externally on mid and hind tibiae. Abdomen. S1 mostly green laterally, dark brown dorsally, S2 largely greenish turquoise laterally and along proximal border of segment, otherwise black dorsally, with greenish turquoise mediodorsal and posterodorsal spots, lateral carina of auricle black; S3 greenish turquoise to yellowish anterolaterally, black after transverse carina and dorsally, with greenish turquoise mediodorsal and posterodorsal spots, mediolateral and posterolateral spots yellowish; S4–6 black with increasingly smaller pale green to yellowish spots, S7–8 with only mediolateral yellowish spots; S9–10 and caudal appendages all black. Structural features: anal loop enclosing 8/9 cells; S3 constricted; auricle with 5 denticles; genital lobe with 2–3 denticles.
Dimensions. Total length 51; HW 40; pterostigma (HW) 3.0.
Female paratype from Venezuela (mature). Live coloration (Fig. 1 b): Head. Face and mouthparts green; transverse bar of T-spot dark brown, almost black in middle, stem pale brown and connected to pale brown basal band, frontoclypeal suture narrowly lined pale brown; occipital triangle dark with pale center. Antenna brown, vertex black. Compound eye mainly green, without blue. Rear of head pale green to yellowish on inferior half and along lower eye margin, dark brown to black on upper half between foramen and occipital triangle and along dorsal eye margin. Thorax. Prothorax pale; pterothorax green with brown mesepisternal stripe, which is arched mesad in upper half and fades out apically; humeral and metapleural sutures lined with brown; minor ill-defined brown areas at lower end of mesepimeron and along interpleural suture; mediodorsal carina and antealar carinae also brown. Wings. Infumated throughout, venation brown, pterostigma light brown dorsally, paler ventrally, covering 4 cells (5 in left FW). Venation: FW with 26/25 ax, HW with 19/20; FW with 18/19 px, HW with 20/19; t in all wings enclosing 6 cells, with the first cell divided; st with 6 crossveins in three wings (5 in right HW); fork of IR2 enclosing 3 rows of cells. Anal loop with 9 cells in three rows; two rows of cells between anal loop and hind border of wing (Fig. 4 a); membranula brown. Legs. Fore leg externally brown-black, except for reddish-brown base of femur. Femora of middle and hind legs reddish brown, becoming black in apical fourth; hind tibiae dark brown to black with yellow streak externally at basal half; tarsi almost black. Abdomen. S1 and S2 moderately inflated, the former without ventral tubercle (Fig. 4 b); lateral and ventral carinae of S2 only weakly converging towards distal end, lateral carina of S2 dark brown (Fig. 4 c). S3 moderately constricted, but lateral and ventral carina closely approximating at level of transverse carina (Fig. 4 d). S1 mostly green laterally, brown dorsally, with small green mediodorsal spot; S2 green laterally, dark brown dorsally, with green mediodorsal line and mediodorsal and posterodorsal spots of same color; S3 green laterally anterior to transverse carina, dorsally brown with green mediodorsal and posterodorsal spots; mediolateral and posterolateral green spots confluent; green color occupying increasingly smaller areas on S4 to S6; S7–10 brown. Fork of ventral process of S10 as illustrated (Fig. 4 f). Both cerci broken and lost, preserved bases brown black (Fig. 4 e).
Dimensions. Total length 54; abdomen 40.5; FW 44.5; HW 44.0; pterostigma (HW) 3.5; hind femur 7.
Remark. This is the female mentioned in De Marmels (1992) under “ Gynacantha sp. near tibiata Karsch, 1891”.
Female paratype from Surinam (mature). Similar to female paratype from Venezuela, with similar wing vein characters but slightly larger.
Dimensions. Total length 61; abdomen 43.5; FW 46; HW 45; pterostigma (HW) 3; hind femur 7.
Remark. This is the female mentioned in von Ellenrieder (2011) under “ Gynacantha sp.”.
Larva (2 ♂ exuviae). Small, almost black in life with pattern of paler spots (Fig. 5), legs with 3–4 dark rings, the two distal tarsal segments pale with dark tip (Fig. 7 h–j). Head. Pattern as in Fig. 6 a; antenna with 7 segments of which the third is longest (Fig. 6 b); length of segments (left/right): 0.33; 0.32; 0.75/0.78; 0.4/0.42; 0.6; 0.36/0.45. Postocular lobe moderately bulging, rounded, its lateral border beset with spinules; occipital margin concave; mandibles (Fig. 6 d) (left/right): 1234 0 a(m)b/1’1234 y a(m)b, molar branch between “a” and “b” laminiform and weakly serrate, in both mandibles; maxilla as illustrated (Fig. 6 c). Labium reaching backwards to hind border of middle coxa; lateral border of prementum beset with 22–27 spinules in apical half; free border of median lobe notably straight, with a minute denticle on each side of median cleft (Fig. 6 e, f); premental setae absent; distal border of labial palp square with notably strong apical hook; distribution and size of palpal setae variable: 3–4 long apical setae, of which 2–3 longest, followed by 1–2 about half size of former and a group of 6–7 very short setae located more basally (Fig. 6 f). Thorax. Pronotum with large black twin spot dorsally (Fig. 6 a); lateral angles of pronotal hind border produced laterally, rounded; prothoracic supracoxal processes well developed, straight, pointed, posterior process slightly broader than anterior in dorsal view (Fig. 7 g). Wing cases reaching to S4, patterned as in Figure 7 f. Abdomen. Pattern of dark and pale areas (exuviae) as in Figures 7 a, b. Lateral spines present on S6–9; male process at base of epiproct triangular, reaching midlength of epiproct; the latter with median carina and ending in two notably well-developed, slightly divergent apical spines; paraproct by far surpassing epiproct (1.2 times as long as epiproct); cercus not quite reaching to base of apical spine of epiproct (Fig 7 c–e).
Dimensions. Total length 28–31; maximum width of head across compound eyes 6.4–6.5; antenna 3.4–3.6; length of prementum 6.2; maximum width of prementum 4.2: hind femur 5.3–5.5; abdomen 18–19; paraproct 3.2.
Distribution (Fig. 9). The species is rare and spottily distributed across lowland rainforest of the Guianas.
Diagnosis. T-spot present. Pterothorax green with distally mesad arched, brown mesepisternal stripe, narrowly dark-lined humeral and metapleural sutures. Middle and hind tibiae dark with yellow streak externally (dorsally). Anal loop enclosing 8–9 cells in three rows, separated from hind border of wing by 2 cell rows. S 3 in male strongly constricted; auricle with 5 denticles; 2–5 denticles on ventral margin of genital lobe. Male cercus not expanded apically, more or less parallel-sided and apically truncated without apical spine, epiproct reaching at least to midlength of cercus.
The new species differs from both G. francesca (Martin, 1909) and G. bartai Paulson & von Ellenrieder, 2005, as these two have epiproct shorter than midlength of cercus, pale legs and only 5 cells in anal loop. Additionally, G. francesca has only one cell row between anal loop and hind border of wing, and G. bartai has brown, unmarked thorax (Paulson & von Ellenrieder 2005). Both are also smaller than the new species. G. adela Martin, 1909, G. chelifera McLachlan, 1896, and G. laticeps Williamson, 1923, have pale legs, as well as sudden apical expansion of male cercus; G. laticeps has also an unmarked thorax. G. convergens has, as well as pale legs and an unmarked thorax, very differently shaped male cercus. G. tenuis Martin, 1909, has differently patterned thorax, brown legs, and only one cell row between anal loop and hind border of wing. In Williamson (1923) the new species keys out with G. jessei Williamson, 1923, because of both having black or black and yellow legs (“ tibiata group”), black tarsi, no ventral tubercle on S1, and apical abdominal segments and appendages of male black. Thoracic color pattern of the new species is indeed similar to that of G. jessei, but caudal appendages of G. jessei show a short epiproct, about as long as a third of cercus length, and mesally concave cercus with apical spine, which in G. dryadula are respectively longer, about as long as half of cercus length, and smoothly convex mesally with truncate tip lacking an apical spine. Female of G. jessei is still unknown; therefore a diagnosis of the females of these two species is still not possible.
The larva of the new species differs from other known larvae of American Gynacantha, beyond its small size, in having epiproct with strong, slightly diverging apical spines, and notably long paraproct. Labial palp with 3–4 long apical setae, of which the first two or three are about twice as long as the following one or two setae; additionally, there is a basal group of 6–7 very short setae.
Habitat and biology. The larva of the holotype was found in the interior of the Amazonian forest in a large rainwater pool (Fig. 8). The pool was 5–7 m long and 10–30 cm deep. Its muddy bottom was covered with a thick layer of leaf litter. Such pools form in the wet season between January and June but dry out during the rest of the year. Other larvae found at the same spot were G. gracilis (Burmeister, 1839), G. membranalis Karsch, 1891, G. auricularis Martin, 1909 (see De Marmels & Neiss 2011), an unidentified species of Orthemis Hagen, 1861, and one of Lestes Leach in Brewster, 1825. The larva of the paratype male from Brazil was recovered from a similar rainwater puddle, although of smaller size.
The male from French Guiana was captured in a feeding swarm in the evening. The surroundings of the collecting locality may be described as humid forest with dappled light areas.
The single female was caught in early afternoon when ovipositing into the roots of a shrub growing from the bottom of a dry depression in deep rain forest (De Marmels 1992).
description: Published as part of Neiss, Ulisses Gaspar & Marmels, Jürg De, 2017, Gynacantha dryadula sp. nov. from the Guiana Shield (Odonata, Anisoptera: Aeshnidae), pp. 563-574 in Zootaxa 4254 (5) on pages 564-573, DOI: 10.11646/zootaxa.4254.5.5, http://zenodo.org/record/556291