Epigomphus bosquenuboso, Haber, 2017

Haber, William A., 2017, Three new species of Epigomphus (Odonata: Gomphidae) from Costa Rica, Zootaxa 4282 (1), pp. 73-94 : 74-87

Epigomphus bosquenuboso new species

Figures 1 a, b; 2b; 3a; 4a; 5a, b, g, h; 6b; 7a; 8a–e; 12.

Specimens examined. 2 males, 5 females. Holotype male: COSTA RICA, Provincia Puntarenas: Monteverde, Quebrada Máquina (10.30, -84.80), 1410 m, 3 June 2012, leg. WAH ( INBIO) . Paratypes: COSTA RICA, Provincia Puntarenas: 1 male, Monteverde Biological Station, small branch of Quebrada Máquina (10.31, -84.81) 1540 m, 25 June 2012, leg. WAH ( FSCA) ; 1 female, same site, 26 May 2013, leg. WAH (WAH); 1 female (described), Monteverde Cloud Forest Reserve, Quebrada Cuecha , 1600 m (10.31, -84.78) 8 May 2006, leg. WAH ( INBIO) ; 1 female, Monteverde, Quebrada Máquina , (10.30, -84.80), 1410 m, 10 June 2012, leg. WAH ( FSCA) ; 1 female, same site, 10 June 2012, leg. WAH (WAH); last instar larva (described), same site, 21 March 2012, leg. WAH (WAH); 1 female, Provincia Heredia: 9 km NE of Vara Blanca (10.14, -84.06), 1500 m, 15 April 2005, leg. G.B. Edwards ( UCMS) .

Etymology. The specific epithet bosquenuboso is considered a noun in apposition and refers to the cloud forest habitat where this species is indigenous and to the Reserva Biológica Bosque Nuboso de Monteverde.

Description. Male holotype. Head. Maximum width 6.9 mm ( Fig. 1 a, 2b); shiny dark brown above; labrum unmarked, base of mandible and gena yellow; top of frons with a cream stripe interrupted in center; distal one third of antennal flagellum pale; eyes dark steel blue in life ( Fig. 1 a); postocellar ridge consisting of a small raised area behind each ocellus divided by a deep groove; posterior margin of occiput with a rounded ridge, the ridge with a pair of mounds on dorsum, each collapsed in center and bordered laterally by three fine grooves; underside of head dark brown with two pale spots along eye margin on each side.

Thorax. Prothorax dark brown, not shiny; midlobe with a pale lateral spot ( Fig. 1 a, 2b). Pterothorax dark brown, not shiny. Mesinfraepisternum with a pale blotch covering lower quarter; upper antehumeral stripe narrow and straight, ending short of narrow pale collar stripe and posterior margin; second antehumeral stripe reduced to a dash at anterior end and separated by 1.5 mm from a faint, small posterior spot; mesepimeron with a narrow central pale stripe; metepisternum with a broader pale stripe narrowing posteriorly and ending well short of posterior margin; metepimeron mostly yellow, but bordered along metapleural suture by brown and with a central brown stripe reaching almost to center of yellow area; metasternum yellow with a dark spot behind coxa. Legs dark brown; femur of foreleg with a barely visible pale area on inner side; outer row of spines on hind tibia specialized, conical-cylindrical with a long spine arising on distal side (the latter often mostly worn off). Wings hyaline with brown tint, venation black; basal subcostal crossvein present only in left wing ( Fig. 3 a); FW Ax 20, 20, with veins 1 and 7 thickened, Px 13, 15; HW Ax 14, 15, with vein 7 thickened; Px 13, 14; pterostigma dark brown, length 3.5 mm, 3.4 mm in FW, 3.7 mm, 3.5 mm in HW. Cubito-anal crossveins 3, 3 in FW; 3, 2 in HW; crossveins above supratriangle between arculus and point of branching of RP 6, 6 in FW, 4, 3 in HW; post-triangular cell space in FW with two rows of cells for 0, 1 cell, followed by one row for 4, 1 cells, followed by two rows for 7, 6 cells.

Abdomen. Dark brown with cream-white markings ( Fig. 1 a); S1–2 brown on upper half, cream-white on lower half, each cream area with a brown mark in middle, auricles mostly pale with 6 small teeth on brown posterior margin; S3 with a broad lateral pale stripe not quite reaching posterior end; S4–6 with pale lateral basal triangles reaching transverse carina; basal half of S7 with a pale dorsolateral band; S9–10 dark brown, unmarked; S10 with a distinct dorsal hump divided by a longitudinal groove and sprinkled with about 25 denticles each in a dorsal and lateral patch on each side.

Abdominal appendages. Cerci 2 mm long, without dorsal denticles ( Fig. 2 b; 4a, b); in lateral view stout with apex downcurved, lower apical margin bearing two stout teeth directed ventrally; in dorsal view inner edge straight, outer edge straight in basal half, curving inward to apex in outer half. Epiproct longer than cerci, 2.3 mm in lateral view; in lateral view broad in basal half, narrower in distal half, apex rounded with a dorsally directed tooth; in ventral view sinus broadly U-shaped at base, narrowed in outer half by incurving branches; no teeth or projections visible; in dorsal view no basal or medial teeth present, but distal tooth with a broadened, fingernailshaped apex ( Fig. 2 b).

Secondary genitalia. Vesica spermalis ( Fig. 5 a, b) most similar in shape to those of E. echeverrii , E. morrisoni , and E. subobtusus ( Fig. 5 c, d; 11), with a well-developed ventral protuberance on dorsal lobe.

Measurements (mm). Total length 48; abdomen 37; FW 35; HW 32, with greatest width 8.4 at nodus.

Female. (Not fully mature, probably second day after emergence, then held in a flight cage for two additional days.). Head. Maximum width 7.7 mm, similar to male ( Fig. 1 b; 6b), except labrum with a faint pale spot in center; gena cream-yellow; postclypeus with light brown in lateral depressions; pale stripe on top of frons divided into two dashes with a dark area between them of about equal length; a sharp horn arising immediately behind each posterior ocellus, the horns parallel and about 1.0 mm long ( Fig. 6 b); postocellar ridge weakly expanded at each side, leaving center shallowly concave; underside of head mostly pale with some darker shading in posterior third; a slight depression next to concave area on the rear margin of each compound eye.

Thorax. Prothorax mostly dark brown, with a pale mark on upper median lobe ( Fig. 6 b). Pterothorax as in male, except pale stripe on metepisternum almost reaches posterior margin, and brown stripe barely intrudes into yellow area of metepimeron. Legs dark with tibiae and tarsi black, the femora dark brown, shading to black at apex; femur of foreleg with a barely visible pale area on inner side. Wings hyaline with dark brown venation ( Fig. 1 b; 3a), pterostigma opaque orange-brown, 4.4 mm long in FW, 4.7 mm in HW; FW Ax = 22, 24 with veins 7, 9 thickened; Px = 15, 17; HW Ax = 16, 16 with veins 7, 8 thickened, Px = 15, 15; cubito-anal crossveins 3, 4 in FW, 2, 2 in HW; crossveins above supratriangle between arculus and point of branching of RP 7, 8 in FW, 4, 4 in HW; post-triangular cell space in FW with two rows of cells for 9, 8 cells.

Abdomen. Dark brown with cream-yellow markings ( Fig 1 b); S1–2 with sides mostly cream-yellow, the yellow with some dark spots; S3 with pale lateral stripe about 4/5 of its length; S4–6 with a pale basal triangle on side; S7 with dorsolateral pale band reaching transverse carina; S8–10 unmarked; epiproct equal to cerci in length; vulvar lamina bifid, the sinus V-shaped with the base slightly rounded ( Fig 3 h.).

Measurements (mm). Total length 53; abdomen 40; FW 41; HW 38 long, 10.0 at maximum width.

Variation in paratypes. In the wild-caught female from Vara Blanca, the labrum is dark brown with all five spots weakly expressed, as is the anterior dash and posterior spot of the second antehumeral stripe. The ridges on top of the head, postocellar horns, and vulvar lamina are identical. This individual also appears to be about one day old. Some variation occurs in the development of pale spots on the labrum. The most pronounced examples have a pair of spots on the extreme lateral margin and another pair to the left and right of the center, and a small central spot. At the other extreme all spots are obscure.

Measurements (mm). Vara Blanca female: head width 7.5; total length 51; abdomen 38; FW 40; HW 38. Ax 22, 23; Px 14, 15. HW Ax 15, 16; Px 15, 15. Four reared females: FW Ax 21–22; Px 14–17; HW Ax 15–17; Px 15– 17. Total length 49–50; abdomen 37–38; FW 37–39; HW 36–37.

Diagnosis. Both sexes: Eyes dark steel blue (blue in E. echeverrii and others), second pale antehumeral stripe broken in the middle, forming a short anterior line and an isolated posterior spot (may be obscure in older individuals). Male: epiproct in ventral view U-shaped with sinuate branches, the tip with a fingernail-shaped hook. Female: a pair of narrow, acute, parallel postocellar horns, a shallow depression behind each compound eye. The thoracic pattern of E. bosquenuboso is most similar to that of E. echeverrii , with which it nearly abuts in distribution. With a hand lens, the shape of the male appendages and female postocellar horns easily separate them. E. corniculatus (type from Suretka, Limon, 70 m, C. Esquivel, April 1988) and E. verticicornis (type from Tuis, Cartago, 700 m, C.H. Lankester, June 1907) are allopatric in distribution, presently known only from lower elevation habitat on the Atlantic slope of the Cordillera de Talamanca in southeast and east central Costa Rica, respectively. E. bosquenuboso is distinguished from these species in the key below.

Larva. Head. Shape triangular with rounded angles ( Fig. 7 a), orange-brown with dark brown markings between antenna bases and between ocelli, eyes dark brown, unmarked, dorsum covered with minute dark brown barrel-shaped setae about 0.01 mm long, a patch of 25‒30 long flexible setae (to 0.8 mm) on each side of antenna base; folded prementum barely reaching posterior to coxa I, broadest near apex and narrowing toward base ( Fig. 8 c), with 9‒11 short rounded teeth on margin of ligula, and a dense fringe of setae about 4X longer than teeth (about 0.2 mm long) attached below them ( Fig. 8 c, e), upperside of prementum with about 10 minute stiff grouped setae about 0.3 mm posterior to base of each mandible; long (to 0.5 mm) flexible setae on lateral margin of prementum (most hairs rubbed off in older individuals); labial palp with 11‒12 teeth; an irregular patch of long flexible setae (to 0.8 mm) on outer margin of labial palp.

Thorax. Prothorax orange-brown; pterothorax dark brown, wing pads dark brown with orange-brown edges; legs dark brown, without markings.

Abdomen. Without middorsal hooks, upperside with outer third orange-brown unmarked, central third mottled with dark brown, underside orange-brown without markings; S7‒9 with broad flattened posterolateral spines that curve slightly outward at apex, lateral margin of S7 on each side with 2‒4 minute tooth-like spinules, S8 with 8‒10 spinules, and S9 with 13‒16 spinules; cerci and paraprocts curved outward at apex; paraprocts notably shorter than epiproct and stubby viewed from ventral side ( Fig. 8 a, b).

Measurements (mm). (Last stage male larva preserved in alcohol) Total body length 27 (with appendages). Head: capsule 4.1 long (on dorsal midline) x 5.6 wide (across eyes), antenna 2.6 long x 0.9 wide (A3), prementum 3.6 long x 3.8 wide at apex, 2.2 wide at base, labial palp 1.6 long (without end hook). Thorax: prothorax 2.3 long x 4.2 wide (across shelf above coxa I), pterothorax 4.7 long x 5.4 wide (behind coxa II), FW pad 6.6, HW pad 7.4, femur III 5.4, tibia III 5.1, tarsus III 3.4 (without claw). Abdomen: 16.5 long x 7.0 wide (across S6), epiproct 1.4, cercus 1.2, paraproct 0.9.

Variation in exuviae.

Measurements (mm) (Mean + standard deviation, n = 5 females; n = 1 male in parentheses). Total body length 25.4 ± 0.49 (23). Head: Antenna length 2.3 ± 0.08 (2.4); head capsule length 3.3 ± 0.14 (3.7); head capsule width 5.9 ± 0.15 (5.6); prementum length 4.2 ± 0.07 (3.6); prementum width 3.6 ± 0.09 (3.5); number of ligula teeth 9.6 ± 1.20 (11). Thorax: pterothorax length 4.4 ± 0.20 (4.1); hind femur 4.8 ± 0.10 (4.9); hind tibia 4.3 ± 0.13 (4.2); hind wing pad 7.7 ± 0.27 (6.1). Abdomen: length 16 ± 0 (15); width at S6 7.5 ± 0.36 (6.8); epiproct length 1.3 ± 0.27 (1.3); cercus length 1.1 ± 0.03 (1.2); paraproct length 0.8 ± 0.05 (.9). The male was outside the range of the 5 females in having shorter total body length, longer antenna, smaller head capsule, shorter prementum, shorter HW pad, and narrower abdomen.

Diagnosis. The paraprocts of E. bosquenuboso are short acute with the inner side convex in ventral view so that the tips curve outward, while in E. armatus , E. echeverrii , E. subobtusus and E. tumefactus , the paraprocts are longer and narrowly acute with the inner side straight so that the tips do not curve outward.

Natural history. Adult males of E. bosquenuboso were collected near the headwaters of small streams in mature forest on the Pacific drainage and near the Continental Divide near Monteverde at elevations of 1450–1550 m. They were collected when they flew down from overhanging trees to circle over pools or to perch on rocks or leaves near the water's edge. Females were also collected after they flew down from trees overhanging spring pools. Two females were collected while they oviposited at the edges of small pools at or near the spring sources at the upper reaches of the same streams where males were observed. All were observed between 10:00 and 12:00 hr local time. One female was clearly observed ovipositing at the edge of a spring pool while perched in full shade above the water edge and extending the abdomen into wet mud at the water edge. One teneral female was collected in a light gap on a cloud forest trail on the Continental Divide above Monteverde; another was photographed by Willow Zuchowski on a different trail about 500 m from the first. An immature female was collected in cloud forest on the north slope of Volcán Barva during the ALAS project. The longest distance between specimens at Monteverde is 5.5 km. The distance between the Monteverde and Vara Blanca populations is 84 km.

While adults were rarely seen—it took 6 years to find the first adult on a stream—larvae were widespread above 1450 m within the region. Larvae were found much more widely distributed along the same forest streams on which adults were collected, but they also occurred in many other streams where adults were not observed and ranged from 1400–1700m.

The only other species of Epigomphus occurring sympatrically with E. bosquenuboso at Monteverde was E. subobtusus , a much more abundant species with a broader distribution, ranging from 650–1600 m on both Atlantic and Pacific slopes. E. echeverrii and E. tumefactus were found in streams slightly below the range of E. bosquenuboso , with an upper limit of 1200 and 1000 m, respectively.

Figures

FIGURE 1. Epigomphus bosquenuboso: lateral scans of a) male; b) female. E. morrisoni: c) lateral scan of male. E. wagneri: d) lateral scan of male.

FIGURE 2. a) E. echeverrii male: thorax, lateral view; apex of abdomen, lateral view; apex of abdomen, ventral view. b) E. bosquenuboso male: thorax, lateral view; abdomen apex, lateroventral view; abdomen apex, dorsal view.

FIGURE 3. Wings of male Epigomphus, dorsal view: a) E. bosquenuboso, b) E. morrisoni, c) E. wagneri.

FIGURE 5. Distal segment of vesica spermalis of Epigomphus species with lateral view on left, dorsal view on right. E. bosquenuboso: a, b; E. morrisoni: c, d; E. wagneri: e, f. E. bosquenuboso female: g) dorsal view of head; h) vulvar lamina.

FIGURE 6. a) E. echeverrii female: above, lateral view of thorax; below, top of head showing postocellar protuberances. b) E. bosquenuboso female: above, lateral view of thorax; below, top of head showing postocellar protuberances.

FIGURE 7. Mature larva of a) E. bosquenuboso and b) E. subobtusus.

FIGURE 8. Larva of E. bosquenuboso: a) apex of abdomen, dorsal view, male; b) apex of abdomen, ventral view; c) prementum, dorsal view; d) right antenna, dorsal view; e) ligula and labial palp, ventral view.