Choroterpes mairena Ávila and Flowers

A, Socorro Ávila & Flowers, R. Wills, 2006, Two new species of Choroterpes Eaton (Ephemeroptera: Leptophlebiidae) from Costa Rica, Zootaxa 1245, pp. 59-68 : 63-66

Choroterpes mairena Ávila and Flowers (new species)

(Figs. 2, 6–8, 11, 12, 14, 17, 18, 21, 22, 24, 25)

Discription

Holotype: Male imago (in alcohol). Length: body 4.8mm, forewing 4.6mm. Head: light brown, washed with blackish brown, antenna light brown. Upper portion of eyes orange­brown, lower portion dark grey. Ocelli whitish, their bases dark brown. Thorax: pronotum light brown with dark brown lateral margins and washed with dark brown on submedian areas; mesonotum dark brown, paler on midline, mesoscutellum piceous; metanotum dark brown. Pleura brown, membranous area light brown. Thoracic sterna dark brown. Forewing (Fig. 2): membrane hyaline, longitudinal veins translucent yellowish brown, cross veins hyaline. Hind wing (Fig. 2): membrane hyaline, C and Sc translucent yellowish brown, remaining veins hyaline. Foreleg: light brown, tibia and tarsus whitish; femur washed with darker brown at mid­length and apex; tarsal formula 0.15: 1.00 (0.52mm): 0.65: 0.34: 0.23. Hind legs whitish, femora with dark brown spots at mid­length and apex, tibiae dark brown at femoral joint. Abdomen (Figs. 6, 8): terga whitish, washed with dark brown, with pale median and lateral markings, tergum 10 brown washed with darker brown. Abdominal sterna white, sternum 9 white with brown basal and lateral margins. Genitalia (Fig. 7): styliger plate pale brown, forceps with an almost quadrate inner basal angle and an exterior basal bulge, whitish; penes light brown, whitish in apical third. Penis lobes elongate, membranous with numerous short spines. Caudal filaments whitish.

Allotype: Female imago (reared with nymphal and subimaginal exuviae). Length: body 4.3mm., forewing 5.0mm. Coloration as in male imago except: head heavily washed with dark brown on vertex and between ocelli. Thorax and pleural sclerites orange­brown, membranes washed with gray. Abdomen bluish green (due to eggs of same color), marked with dark brown as in male imago. Subanal plate yellowish white at base, translucent apically, cone­shaped without apical notch.

Mature nymph: Body length 4.1–5.8mm. Head yellowish brown washed with dark brown, clypeus whitish, and whitish spots present anterior to median ocellus and between lateral ocelli and eyes. Area between ocelli and sublateral spots on vertex washed with black. Antenna white, basal segments pale yellowish brown. Mouthparts: labrum (Fig. 14) with maximum length less than maximum width, anteromedian emargination well developed, a row of short dorsal subapical seta present behind anteromedian emargination and a row of long dorsal setae on apical third, length of this row slightly less than threefourths the total width of labrum; mandibles (Figs. 17, 18) with a prominent anterolateral flange on the outer margin at the base of incisors, outer margins obtusely angled, a short row of setae at angle and short seta above basal condyle; maxilla (Fig. 21) with anteromedian tooth obsolete, galea­lacinia with inner subapical row of 13 pectinate setae; hypopharynx as in Fig. 22; segment 2 of labium 4/5 the length of segment 1, segment 3 3/ 4 the length of segment 2, (Fig. 22) with 6–7 large dorsal seta on segment 3; labrum, basal 2/3 of dorsal surface of mandibles, outer margin of maxilla and posterior margins of segment I of labial palpi brown, a pale spot on dorsal side of mandibles at angles; remaining mouthparts pale yellowish brown. Thorax: terga yellowish brown, pronotum with dark brown sublateral bands; mesonotum washed with brown on lateral margins; pleura grey, sterna pale yellowish brown. Legs: yellowish brown, femora with dark brown median and apical spots, area between these spots pale yellow; claw with denticles divided into two sections of 7+3 denticles (Fig. 12) with denticles in both sections increasing in size toward apex. Abdomen: terga yellowish brown, washed with darker brown,

FIGURES 13–24. Choroterpes , nymphal mouthparts. Figs. 13, 15–16, 19–20, 23. C. gregoryi ; 13, labrum; 15, left mandible, dorsal; 16, right mandible, dorsal; 19, maxilla, ventral; 20, hypopharynx, ventral; 23, labium: right, ventral; left, dorsal. Figs. 14, 17–18, 21–22, 24. C. mairena : 14, labrum; 17, left mandible, dorsal; 18, right mandible, dorsal; 21, maxilla, ventral; 22, hypopharynx, ventral; 24, labium: right, ventral view; left, dorsal.

segments II–VIII with a small pair of submedian spots on basal margin and a larger pair of sublateral spots at midlength, segment IX yellowish white with brown basal margin, segment X yellowish white with brown apical margin; sterna yellowish white, shaded with yellowish brown on lateral margins; posterolateral spines present on segments III or IV–IX Gills (Fig. 11) whitish grey, tracheae grey­violet. Caudal filaments pale yellowish brown.

Specimens examined

Male imago HOLOTYPE labelled COSTA RICA, Guanacaste, Cuajiniquil, Río Mairena , 21 m. N 10° 55’48.900” W 85° 41’ 12.12”, 25/01/2005, Col. R. W. Flowers, S. Ávila, M. M. Chavarría. Female imago ALLOTYPE (with nymphal and subimago exuvia), same locality and date as holotype, Col. R. W. Flowers, S. Ávila. PARATYPES (19 ɗɗ, 11 ΨΨ, 91 nymphs): Guanacaste Province, 13 ɗɗ, 5 ΨΨ, 31 nymphs (2 ɗɗ, 5 nymphs, FAMU; 2 ɗɗ, 1 Ψ, 3 nymphs, IFML; 2 ɗɗ, 2 ΨΨ, 4 nymphs, MZUCR; 7 ɗɗ, 2 ΨΨ, 20 nymphs, INBio) same data as holotype; 1 Ψ subimago (with nymphal exuvia) (INBio), same locality and collectors as allotype, 27/01/2005; 31 nymphs (10, MZUCR; 21, INBio), same data as holotype; Area de Conservación Guanacaste, Parque Nacional Santa Rosa, Sector Santa Elena, Río Calera, 315m, N 10°51’50.0” W 85°39’49.4”, 4 ɗɗ, 4 ΨΨ (INBio), 2/12/2004, Col. S. Ávila, R. W. Flowers; 9 nymphs (4, MZUCR; 5, INBio), 13/07/2004, M.M. Chavarría, R. W. Flowers; 1 nymph (INBio), N 10°51’59.5” W 85°39’48.9”, 5/09/2004, M. M. Chavarría;. 4 nymphs (INBio), Queb. Calera, 315m, 10°52’13.4” W 85°38’49.5”, 02/12/2004, S. Ávila, R. W. Flowers, M. M. Chavarría; 7 nymphs (INBio), N 10°52’48.7” W 85°38’49.1”, 05/09/2004, M. M. Chavarría; Río Cuajiniquil, cruce de camino a Potrero Grande, 320m, N 10°52’48.7” W 85°36’41.3”, 2ɗ, 2Ψ, 7 nymphs (INBio), 01/12/2004, S. Ávila, R. W. Flowers, M. M. Chavarría; 1 nymph (INBio), Queb. Loros, 368m. N10°50’50.9” W 85°41’52.8”, 03/12/2004, S. Ávila, R. W. Flowers, M. M. Chavarría; 4 nymphs (INBio), Islas Murcielagos, Isla San José, N 10°51’44.2” W 85°54’47.4”, M.M. Chavarría, E. Sequiera.

Ecology

This species is currently known only from the Santa Elena Peninsula where it is common and widespread in temporary streams that are without water five months of the year. Adults and emerging nymphs were most common in February in isolated pools in which the water decreased measurably from day to day. Other mayfly genera found in association with C. mairena were Ulmeritoides acosa and U. chavarriae , Caenis sp., Tricorythodes sp., and Americabaetis sp.

Diagnosis

Choroterpes mairena can be separated from other Middle and Central American species of Choroterpes by the following combination of characters. In the imago: (1) abdomen with color pattern as in Figs. 6 and 8, and with U­shaped dark margins on sternum IX: (2) male genitalia with basal expansion of forceps 1/3 of their total length: (3) penes with their apices rounded and with numerous short spines. In the nymph: (1) mandibles with prominent anterolateral flange; (2) maxillae with 13 apical pectinate setae; (3) gills (Fig.11) with outer and inner processes of inner lamelae elongate and pointed but with only outer process of outer lamella acutely pointed. Choroterpes mairena is most similar (in the nymph) to C. ungulus Lugo­Ortiz & McCafferty , but can be distinguished by the pointed apical angles of the gills (all angles are blunt and rounded in C. ungulus ).