Gynacantha vargasi, Haber, 2019

Haber, William A., 2019, Gynacantha vargasi (Odonata: Anisoptera: Aeshnidae) sp. nov. from Costa Rica, Zootaxa 4612 (1), pp. 58-70 : 58-70

Gynacantha vargasi sp. nov.

(Figs 1–7)

Holotype. Male ( INBIO–MNCR), COSTA RICA: Provincia Limón, 11 km SSW of Pocora, Reserva Las Brisas , Río Cuarenta y Cinco (10.07, -83.63, 850 m asl), 23 June 2009, Juan Chávez, Ronald Vargas, William Haber leg.

Paratypes. Male ( WH), COSTA RICA: Provincia Heredia, 11 km SE La Virgen, Braulio Carrillo National Park, vicinity Cascante Refuge , east side of Río Peje , Quebrada Lajas (10.33, -84.07, 500 m asl), 19 April 2003, Ronald Vargas leg. Female ( UCMS) , Provincia Limón, 14 km WSW of Siquirres, Reserva Las Brisas, Río Cuarenta y Cinco (10.07, -83.63, 850 m), 23 August 2006, Ronald Vargas leg.

Allotype. Female ( INBIO–MNCR), COSTA RICA: Provincia Alajuela, Monteverde Cloud Forest Biological Reserve , Río Peñas Blancas Valley , Refugio Eladio , Quebrada Pavoncillo (10.31, -84.72), 800 m, 20 NOV 2004, Eladio Cruz leg.

Etymology. This species is named in honor of Ronald Vargas Castro, one of Costa Rica’s great naturalists, a trusted companion who has accompanied me on many Odonata expeditions in Costa Rica and Ecuador and who has collected numerous rare and undescribed species of Odonata , including two of the four known specimens of this new Gynacantha .

Description of holotype.

Head. Maximum width 8.8, eyes dark brown (dark green in life), labium light orange-brown, unmarked; underside of head cream in outer half, shading to black on inner half; labrum cream, unmarked; anteclypeus gray-green; postclypeus blue-gray with two ill-defined dull orange spots bordering the center; antefrons light brown shading to dark brown at upper margin; postfrons brown with a black spot centered on anterior side about 1/2 width of frons, no T-spot stem present; vertex shiny black; antenna dark brown; eyes dark green and black in life; vertex black; occipital triangle green.

Thorax. Prothorax with forelobe light brown; midlobe light brown with darker brown and black markings; hindlobe black in middle 1/3, light brown laterally (Figs. 1a, 2a). Pterothorax dark brown with lime green markings; mesepisternum with a narrow collar stripe and an arching antehumeral stripe, free at each end; mesepimeron with a complete, nearly straight and uniform stripe in center; metepisternum mostly brown with a small green mark anterior to spiracle; metepimeron with a broad stripe covering most of surface, but separated from upper and lower sutures; mesinfraepisternum and metinfraepisternum light brown; metasternum brown with some pale shading.

Legs. Fore femur dark brown at base, shading to black in distal half, inner surface yellow on basal half, tibia FIGURE 1. Gynacantha vargasi sp. nov. a) holotype male, b) allotype female. and tarsus black; mid and hind femora orange-brown basally, shading to black in distal third; tibia black with dorsal side yellow in basal 4/5; tarsi black.

Wings. (data for left wing precede those for right wing) Transparent with slight brown tint, veins brown, FW Ax (left, right) 27, 26 with 1 and 9 thickened; Px 23, 23; HW Ax 21, 22 with 1 and 10 thickened; Px 23, 21; poststigmatal cross veins in FW 6, 5; in HW 7, 4; FW triangle with (left, right) 6, 6 cells; subtriangle 3, 2 cells; supratriangle 6, 7 crossveins; median space free; cubito-anal crossveins 8, 8. HW triangle with 6, 6 cells, subtriangle with 2, 2 cells, supratriangle with 5, 5 crossveins; median space free; cubito-anal crossveins 6, 6; anal loop with 13, 11 cells; anal loop separated from posterior margin by 1, 2 rows of cells ( Fig. 3a ).

Abdomen. S1 red-brown, shading to dark brown on dorsum; S2 with dorsum and sides black, a narrow blue stripe on midline; green on side at base, green bordering transverse carina, a blue patch above auricle, a wide blue stripe bordering posterior margin, auricle black with a blue patch on dorsum, ventrally bright yellow-green with black edges; 5–6 stout recurved teeth on posterior edge ( Fig. 6a ); 5, 8 minute black denticles bordering ventral carina, but not in a line ( Fig. 6a ). S3 greatly narrowed both laterally and dorsally (Figs. 1a, 5a, 6a); basal half redbrown, shading to black on posterior half; lower side with a blue patch at base, an inconspicuous green line border ing transverse carina on posterior side, two lateral blue spots at apex; S4−10 black with S4−8 having inconspicuous blue spots and streaks on lower sides.

Caudal appendages. Left cercus detached (Fig. 1a). Appendages black; cercus 5.5; epiproct 2.6, straight in api- cal 2/3, apex minutely emarginate in dorsal view. Cercus with medial margin slightly decumbent medially, and with an asymmetric distal dorsal lobe angled medially to plane of cercus ( Fig. 4 , a−d).

Measurements (mm). Total length without cerci 61; abdomen 47, cerci 5.5; FW 44; HW 43 with width at nodus 12; pterostigma length on costal vein 3.5, 3.4 in FW; 3.2, 3.1 in HW.

Description of allotype.

Head. Maximum width 9.3 mm. Eyes dark brown (not seen alive); labium dull orange-brown shading to cream posteriorly; underside of head cream-brown bordering eye margins, shading to black in center; labrum orangebrown, unmarked; ante- and postclypeus light brown; antefrons orange-brown, postfrons brown with anterior half black, no T-stem; vertex black; occipital triangle yellow-green.

Thorax. Prothorax forelobe with light brown margins, darker brown in middle; midlobe and hindlobe light brown without darker markings. Pterothorax ground color dark brown dorsally shading to light orange-brown ventrally; venter unmarked; pale markings yellow-green, duller and wider than in male; mesepisternum with dorsal carina all brown; with a slender collar stripe; antehumeral stripe arched upward at middle; mesepimeron with a broad central stripe, narrowed posteriorly; metepisternum all brown; metepimeron with a broad complete stripe covering most of sclerite, free at each end and not reaching either suture; mesinfraepisternum brown with weak green shading; metinfraepisternum brown and unmarked.

Legs. Fore femur orange-brown in basal half, shading to black in apical half, inner surface cream on basal 2/3, tibia and tarsus black; mid and hind femora orange-brown shading to black in apical 1/4 to 1/3, tibia dark brown with dorsal side tan, apical 1/4 black; tarsi black.

Wings. (data for left wing precede those for right wing) Distal half of right FW missing (Fig. 1b). Distinctly tinted brown with veins brown to dark brown; pterostigma light brown; Ax of FW 31, with 1 and 10 thickened; Px 26; tip of right wing missing. In HW Ax 23, 21 with 1 and 9 thickened; Px 26, 27; HW triangle with 6 plus 2 tiny cells, 6 cells; subtriangle with 2, 2 cells, supratriangle with 7, 7 crossveins; anal loop with 12, 13 cells; anal loop separated from posterior margin by 1, 2 cell rows. A subcostal crossvein present anterior to first Ax in left FW and left HW. FW triangle with 8, 8 cells; subtriangle with 2, 2 cells; supratriangle with 9, 9 crossveins, cubito-anal crossveins 7, 7 in FW 6, 6 in HW; crossveins between arculus and branching of R 16, 15 in FW 11, 11 in HW (Figs. 1b, 3b).

Abdomen. Cerci broken near base and missing. S1 orange-brown; S2 black above lateral carina, greenish below, extensive blue shading on posterior half above lateral carina; S3 brown with a blue basal patch on side; S4−10 dark brown shading to black posteriorly ( Fig. 4g, h ; Fig. 5b, c ).

Measurements (mm). Total length without cerci 64 (cerci broken); abdomen 50; FW 48; HW 49, 49, width at nodus 13. Pterostigma length on costal vein 3.8 in FW; 3.5, 3.6 in HW.

Variations. Both males are mature. The Río Peje male, with wings slightly darker, appears to be older than the holotype male and comparable in age to the two females. It is slightly smaller, with head width, abdomen, and FW 8.7, 46, and 43, respectively, and the anal loop has only 9 and 10 cells. The color pattern elements are the same in both. The labrum and face are darker orange and shading more to blue in the La Virgen male. The cercus apex of the holotype is twisted about 60 o clockwise; those of the Río Peje male are turned about 20 o. Because the twisted cercus is evident in the fresh holotype male (Fig. 1a), scanned before preservation and shows the same orientation after drying, this state appears to be natural. The Río Peje male was preserved in acetone and dried before analysis.

Both females are mature with the wings shaded brown. The color patterns are without significant variation but duller overall than in the males. The Las Brisas female is smaller, with head width, abdomen, and FW 9.1, 51, and 46, respectively and the anal loop has only 11 and 10 cells.

The separation of the anal loop from the posterior wing margin is variable – the normal state appears to be two rows of cells between the loop and the margin as in the Las Brisas female. The other female and both males have at least one elongated cell bordered by two cell rows joining the loop and margin in each wing. A crossvein basal to the first thickened antenodal vein appears only in one FW and one HW of the Río Peñas Blancas female.

Diagnosis. Males of Gynacantha vargasi can be separated from all other species by the bright green thoracic stripes, mid and hind legs with femora orange-brown tipped with black, and dorsal side of the middle and hind tibia yellow; the length of the epiproct at about half the length of cercus, and the unique angled distal lobe of the cercus. Females are distinct in the T-mark on the frons lacking a stem, the color patterns of the thorax, and the yellow to tan mid and hind tibia.

Within Costa Rica, the lime-green lateral thoracic stripes are similar in size and shape to those of Gynacantha caudata Karsch, 1891 ; Aeshna williamsoniana Calvert, 1905 ; Rhionaeschna cornigera ( Brauer, 1865) ; and R. psilus ( Calvert, 1947) , all of which may overlap in distribution and habitat with G. vargasi ( Fig. 2 ). Gynacantha caudata is distinct in having entirely pale mid and hindlegs. The top of the frons of G. vargasi has a black T-mark lacking a stem, while the frons of A. williamsoniana is all black, and R. cornigera and R. psilus have a T-mark with a broad stem. Gynacantha vargasi , G. caudata , and the South American G. tenuis ( Martin, 1909) and G. francesca ( Martin, 1909) are the only species of New World Gynacantha with bright-green thoracic stripes.

Gynacantha vargasi belongs to the group of species lacking crossveins basal to the first thickened Ax vein and Pt less than 4 mm long. Gynacantha helenga Williamson & Williamson, 1930 ; G. jessei Williamson, 1923 ; and G. tibiata differ in having the epiproct only about 1/3 the length of the cercus. Also, these species lack the distinctive thoracic stripes of the new species. The femora of the mid and hind legs are black apically, differing from G. caudata ; G. klagesi Williamson, 1923 ; G. laticeps ; and G. auricularis , but similar to G. dryadula Neiss & De Marmels, 2017 and G. jessei . Gynacantha dryadula , G. jessei , and G. laticeps have a uniformly colored thorax. Also, G. dryadula has a unique truncate cercus tip. Gynacantha caudata , G. francesca and G. tenuis share green lateral thoracic stripes with G. vargasi , but are smaller species (HW 39 to 41), and the femora are not tipped with black.

Habitat and Ecology. Adults of G. vargasi were all collected on the Caribbean slope of Costa Rica during the wet season in April, June, August, and November. While the larval habitat and oviposition sites are unknown, the holotype male was collected while patrolling over a residual pool in a seasonal stream at a time when that section of the stream had no running water. The Las Brisas female was collected in August at the edge of the same stream, then with flowing water, while perched during the morning on an understory palm in secondary forest. The Río Peñas Blancas female was collected in November when it flew into a building while foraging with other aeshnids during mid-day over a grassy yard at a height of about 3 m.

Figures

FIGURE 2. Images of head and thorax of Gynacantha vargasi and similarly patterned species from Costa Rica. G. vargasi: a) male, b) female; G. caudata: c) male, d) female; Aeshna williamsoniana: e) male, f) female; Rhionaeschna cornigera: g) male, h) female.

FIGURE 3. Wings of Gynacantha vargasi sp. nov.: a) holotype male, b) allotype female.

FIGURE 4. Abdominal appendages of Gynacantha species. Gynacantha vargasi male holotype: a) dorsal view; b) mediodorsal view; c) external lateral view; d) cross section of right cercus at center of dorsal lobe, posterior view. Gynacantha tenuis male (Dept. Loreto, Peru): e) cross section of right cercus at middle of dorsal lobe. Gynacantha caudata (Prov. Guanacaste, Costa Rica): f) cross section of right cercus at center of dorsal lobe, posterior view. Gynacantha vargasi, female allotype: g) abdominal segments 8−10, lateral view; h) forked process on abdominal segment 10, posterior view.

FIGURE 5. Gynacantha vargasi, abdominal segments 1−3: a) male holotype, lateral view; b) female paratype (Las Brisas), lateral view; c) same female, ventral view.

FIGURE 6. Abdominal segments 1−2 (ventral view) of male Gynacantha species showing secondary genitalia and auricles: a) G. vargasi, male holotype; b) G. caudata, Prov. Guanacaste, Costa Rica; c) G. tenuis, Dept. Loreto, Peru; and d) G. tibiata, Prov. Limón, Costa Rica.