Choroterpes gregoryi Ávila and Flowers, 2006

A, Socorro Ávila & Flowers, R. Wills, 2006, Two new species of Choroterpes Eaton (Ephemeroptera: Leptophlebiidae) from Costa Rica, Zootaxa 1245, pp. 59-68 : 60-63

Choroterpes gregoryi Ávila and Flowers , new species

(Figs. 1, 3–5, 9, 10, 13, 15, 16, 19, 20, 23, 25)

Discription

Holotype. Male imago (in alcohol, genitalia and one set of wings on slides): Length: body 4.7mm, forewing 4.8mm. Head: brown, washed with black, antenna translucent yellowish brown, scape and pedicel washed with reddish brown. Upper portion of eyes olive brown, stalk very short, lower portion dark gray. Ocelli whitish, their bases dark brown. Thorax: pronotum yellowish brown washed with black laterally and on basal margin; meso­ and metanota chestnut brown, margins and carinae darker. Pleura orangebrown washed with dark brown, a diagonal area above mesocoxae washed with black. Thoracic sterna orange brown. Forewing (Fig. 1): membrane hyaline, translucent yellowish brown at base; longitudinal veins translucent brown, cross veins hyaline. Hind wing (Fig. 1): membrane hyaline, veins C and Sc translucent yellow in basal half, remaining veins hyaline. Foreleg: yellowish brown, tarsus lighter; femur with a dark brown spot at mid­length; tarsal formula: 0.18:1.0 (0.56mm): 0.75:0.39:0.18. Hind legs translucent yellow, femora with dark brown spots at mid­length and apically, tibiae darker brown at the femoral joint. Abdomen (Fig. 3, 5): terga translucent yellowish brown, washed with dark brown, with pale median, submedian and lateral markings. Abdominal sterna translucent yellowish brown, sternum IX with brown basal and lateral margins.

Genitalia (Fig. 4): forceps expanded in basal 1/3; styliger plate whitish, forceps brown, penes whitish. Penis lobes elongate, membranous, with a tiny pair of spines in apical third along midline. Caudal filaments broken off and missing.

Allotype. Female subimago (reared with nymphal exuviae). Length: body 4.6mm, forewing 5.1mm. Coloration as in male imago except: head yellowish white marked with dark brown between ocelli and on vertex; antenna whitish. Thorax yellowish brown, meso­ and metanota darker brown laterally, membranes whitish washed with grey. Wing membrane whitish, veins translucent. Legs yellowish white, dark spots as in male imago except fore femur has an additional apical dark spot. Abdomen yellowish white with dark brown markings as in male imago. Subanal plate yellowish white, cone­shaped, without apical notch. Caudal filaments white with narrow dark bands on annuli.

Mature nymph (in alcohol): Body length 4.6–5.1mm. Head: yellowish brown washed with darker brown, pale spot anterior to the median ocellus, and pale areas between eyes and lateral ocelli. Vertex and area between ocelli washed with black. Antenna yellowish white. Mouthparts: labrum (Fig. 13) with maximum length slightly less than maximum width, anteromedian emargination well developed with three irregular denticles, a row of short dorsal subapical seta present immediately behind anteromedian emargination, and a second row of long dorsal present on apical third, length of this row slightly more than one third the total width of labrum; mandibles (Fig. 15, 16) with outer margins obtusely angled, a tuft of setae at angle; maxilla (Fig. 19) with anteromedian tooth obsolete, galea­lacina with inner subapical row of 17–18 pectinate setae; hypopharynx as in Fig. 20; segment 2 of labial palpi 3/4 the length of segment 1, segment 3 slightly shorter than segment 2, (Fig. 23) with 5 large dorsal seta on segment 3; labrum, basal 2/3 of mandibles, outer margin of maxilla brown, labium yellowish brown. Thorax: terga yellowish tan, pronotum with crescent­shaped submedian spots and lateral margins dark brown; mesonotum washed with brown on lateral margins; pleura washed with dark brown, sterna yellowish brown. Legs: yellowish white, femora with dark brown median and apical spots, tibiae and tarsi pale yellowish brown, tarsi paler at base and apex; claw with denticles divided into two sections of 8–10+4–5 denticles (Fig. 9) with denticles in both sections increasing in size toward apex. Abdomen: terga washed with dark brown, pale markings as in male imago; sterna yellowish brown, male with dark brown at base of each segment in lateral 1/4; female with sterna washed with orange­brown; posterolateral spines present on segments IV–IX. Gills (Fig. 10) whitish grey, trachea gray­violet, secondary tracheae lacking side branches. Caudal filaments pale yellowish brown.

Etymology

gregoryi , masculine. This species is dedicated to the senior author’s youngest son, Gregory Juseppy Porras, who at six years old is already an enthusiastic aquatic entomologist.

FIGURES 1–12. Choroterpes . 1, 3–5, 9–10. C. gregoryi ; 1, wings; 3, tergites II–VII of male abdomen; 4, male genitalia; 5, segments II–VII of male abdomen, lateral; 9, gill IV; 10, foreclaw of nymph. 2, 6–8, 11–12 C. mairena ; 2, wings; 6, tergites II–VII of male abdomen; 7, male genitalia; 8, segments II–VII of male abdomen, lateral; 11, gill IV of nymph; 12, foreclaw of nymph.

Specimens examined

Male imago HOLOTYPE labeled COSTA RICA, Guanacaste, Nandayure, Queb. Maquenco. Fecha: 16­XII­2005 Elev. 392m. N 9° 58’21.48” W 85° 15’35.52” Col. S. Ávila, R. W. Flowers. Female subimago ALLOTYPE labeled COSTA RICA, Puntarenas, Golfito, Pavones, Queb. El Macho, Fecha: 16­IV­2005, Elev. 40m. N8° 20’39.78” W 83° 08’09.6” Col. S. vila, Cria 21­IV­2005. PARATYPES (3 ɗɗ, 1 ΨΨ, 10 nymphs): 2 ɗɗ, 5 nymphs (2 nymphs, MZUCR; 2 nymphs, INBio) same data as holotype; 1 ɗ subimago (reared), 1 Ψ subimago (reared), 1 nymph (INBio), same data as allotype; 3 nymphs (INBio), same locality as allotype, Fecha: 18­I­2005, S. Ávila, R. W. Flowers; 1 nymph (INBio), Puntarenas Province, Parrita, Queb. Pirrís, 47m. N 9° 36’ 1.02” W 84° 19’ 19.08” Fecha: 13/02/2005; 3 nymphs (INBio), San José Province, La Cangreja, Queb. Grande, 200m, 13­II­2005, S. Ávila, R. W. Flowers. Nymphs from La Cangreja had a paler ground color on the abdomen and correspondingly darker lateral markings than the nymphs from the other localities.

Ecology

This species was collected from leaf packs in pools and in slow­flowing areas of streams along the southern Pacific coast of Costa Rica. Associated mayfly species include Ulmeritoides acosa Ávila & Flowers , Tikuna atramentum (Traver) , Farrodes sp. Thraulodes sp. Caenis sp., and Tricorythodes sp. All streams in which this species was found are permanent.

Diagnosis

Choroterpes gregoryi can be separated from other Middle and Central American species of Choroterpes by the following combination of characters. In the imago: (1) abdomen dark with color pattern as in Figs. 3,5; (2) male genitalia with basal expansion of forceps 1/3 of their total length; (3) apices of penes rounded. In the nymph: (1) mandibles lacking anterolateral expansion basal to incisors; (2) maxilla with 17–18 apical pectinate setae and lacking an anteromedian tooth; (3) abdominal gills (Fig.) with outer and inner processes of both lamellae pointed. Of the other Western Hemisphere Choroterpes , C. gregoryi most closely resembles dark forms of C. basalis (Banks) from the eastern United States, but can be distinguished by the following combination of characters: In the imago the penes of C. basalis are more elongate than those of C. gregoryi and their apices are slanted outward. In the nymph, the labrum of C. basalis lacks the low irregular denticles found in C. gregoryi .