Ulmeritoides chavarriae Ávila and Flowers, 2005

Ávila, Socorro & Flowers, R. Wills, 2005, New species and records of Ulmeritoides (Ephemeroptera: Leptophlebiidae) from Costa Rica, Zootaxa 1010, pp. 1-14 : 7-9

Ulmeritoides chavarriae Ávila and Flowers , new species

(Figs. 3, 4, 7, 8, 11, 15, 17, 20–22)

Holotype: Male imago (in alcohol, with nymphal exuvium). Length: body 7.2 mm; forewing, 7.2 mm. Head: dark brown, orange–yellow spots at base of antennae, below median ocellus, and between lateral ocelli; antenna translucent brown. Upper portion of eyes orange–brown, lower portion blackish. Ocelli whitish, their stalks dark brown. Thorax: pronotum yellowish brown, washed with black laterally and a black streak on midline; mesonotum shining brown, margins and carinae darker; metanotum orange brown at base, piceous brown laterally. Pleura yellowish tan washed with darker brown. Thoracic sterna chestnut brown, washed with black. Forewing (Fig. 3): membrane hyaline, costal and subcostal area shaded with light brown, a dark brown patch on wing base. Longitudinal veins and cross veins translucent brown, cross veins between costa and Rs narrowly shaded with dark brown; 7 cross veins basal to bulla. Hind wing (Fig. 4): membrane hyaline, a brown spot at base; C, Sc and R 1 brownish, remaining veins hyaline; cross veins in costal area brown, remaining cross veins hyaline. Foreleg: coxa and trochanter tan washed with dark brown, femur orange brown, washed with dark brown dorsally and on apex, a dark brown spot at middle; tibia dark brown, tarsus brown, apical segment paler. Middle and hind legs orange yellow with dark brown dorsal spot on apex of femora, hind femur washed with brown at base. Abdomen: terga I–VII brown, terga VIII–X orange brown, terga with dark brown markings as in Fig. 11, markings reduced on terga IX and X. Sterna I–VII translucent brown weakly washed with black; sterna VIII and IX orange brown. Genitalia (Fig. 7): styliger plate orange–brown, forceps and penes smoky brown. Penis lobes (Fig. 8) elongate, compressed and curved dorsally, with a triangular ventral projection pointed toward midline at its tip. Caudal filaments chestnut brown.

Allotype: Female imago (in alcohol with nymphal exuvium). Length: body 6.9 mm; forewing 7.9 mm. Coloration as in male imago except: head yellowish white, washed with dark brown between ocelli; antenna yellowish brown. Thorax and pleura orange–tan, washed with black above mesocoxa. Wing membrane translucent, longitudinal veins pale, crossveins brown, pale posteriorly. Legs as in male imago except for usual sexual differences in foreleg. Abdomen yellowish tan with dark brown markings as in male imago; sterna yellowish white, washed with brown. Subgenital plate translucent brown with dark brown lateral margins. Caudal filaments chestnut brown.

Mature nymph (in alcohol): Body length 6.6–11.4 mm. Head: yellowish tan to yellowish brown, pale spots anterior to median ocellus and between eyes and lateral ocelli. Antenna yellowish brown. Mouthparts: labrum ( Fig. 15) with maximum length 1/2 width, anteromedian emargination well developed, with 5 weakly developed or obsolete denticles; maxilla ( Fig. 17) with anteromedian tooth very small, galea–lacinia with inner subapical row of 14–17 pectinate setae, subapical setae closely parallel to apical setae; segment 2 of labial palpi ( Fig. 21) subequal to segment 1; segment 3 slightly greater than 1/4 length of segment 2; segment 3 ( Fig. 20) with 13 denticle­like setae on inner margin and tip; clypeus, labrum, basal 2/3 and base of molars of mandibles, basal 1/2 of maxillae and segment 1 of palp and labium yellowish brown, submentum yellowish brown with 2 pale basal spots. Thorax: terga yellowish tan to brown, washed with black on lateral margins, pleura and sterna yellowish tan. Legs: yellowish tan to brown, coxae washed with black; femora dark at apex, hind femur with a dark basal spot, forefemur with a dark median spot on inner surface. Tibiae and tarsi tan to brown, tarsi paler at base and apex; in very mature nymphs the foretibiae and basal half of fore tarsi dark brown. Abdomen: terga yellowish brown to dark brown, with dark brown lateral and apical markings as in male imago, apical markings often weak or absent; sterna yellowish brown washed with darker brown. Gills grey, tracheae and fimbriae gray­violet. Caudal filaments yellowish brown, alternating segments slightly darker.

Etymology. This species is dedicated to María Marta Chavarría Diaz, Programa de Investigatión of the Area de Conservación Guanacaste, who collected many specimens in the type series, and who has contributed significantly to the success of this project.

Specimens Examined. (17♂♂, 5♀♀, 81 nymphs)(INBio): Male imago HOLOTYPE (with nymphal exuvium) labeled COSTA RICA, Guanacaste Province, Area de Conservación Guanacaste, Parque Nacional Santa Rosa , Sector Santa Elena , Río Cuajiniquil at road to Playa Potrero Grande L _N_ 360103–317790, 2–XII–2004, S. Ávila, M.M. Chavarría, R.W. Flowers. Female subimago ALLOTYPE. same data as holotype. PARATYPES: 15 ♂♂, 3 ♀♀ imagos (1 ♂, 1 ♀ FAMU; 1♂ IFML; 15 ♂♂, 2 ♀♀ INBio) same data as holotype, 30 nymphs (5 FAMU; 5 MZUCR; 20 INBio), same locality as holotype, X–2004, M.M. Chavarría D.; 14 nymphs, same locality as holotype, L_N_360103–3317790, 2–XII–2004, M.M. Chavarría; 1 ♂, 1 ♀ imago, 15 nymphs (5 IFML; 10 INBio), same locality, 1–XII–2004, M.M. Chavarría, S. Ávila, R. W. Flowers; 7 nymphs, same locality, L_N_360147–315723, 17–X–2004, M. M. Chavarría; 15 nymphs, same locality, 24–I–2005, S. Ávila, R.W. Flowers. Association of adults and nymphs is by rearing .

Ecology. This species lives in pools in a seasonally dry river in an area which generally lacks rain for five months of the year. Nymphs have been collected from October to January; during July, two months into the rainy season, no nymphs were found. In December nymphs were very abundant in deep pools and emergence was observed; by late January these pools were greatly reduced in volume and nymphs were much less abundant. Subimagos were collected at lights from 9–10PM and emergence of imagos took place the following morning from 10–11AM. Based on observations to date, we conclude that this species has a short life cycle to avoid both the long dry season and flash floods that occur during the early part of the rainy season.

Diagnosis. Ulmeritoides chavarriae can be separated from all other species of Ulmeritoides by the following combination of characters. In the imago: (1) fore wings with costal and subcostal areas shaded with brown; (2) penis lobes flattened, upturned, and with ventral projection turned inward; (3) abdominal color pattern as in Fig. 11. In the nymph: (1) maxillary tusk very small; (2) middle and hind femora with few spines on exterior surface; (3) maxilla with subapical row of setae closely parallel to apical setae ( Fig. 17); (4) abdomen with dark apical bands usually lacking.

Ulmeritoides chavarriae is most similar to U. acosa , but differs consistently in the adult in the color pattern, which in U. acosa has an overall orange cast and a pattern of light spots and dark bands while in U. chavarriae the color is dark yellowish brown and the pattern is at most vague darker bands, and in the ventral projections of the penes, which turn inward in U. chavarriae but not in U. acosa . Nymphal differences are not as consistent; the position of the subapical row of setae on the maxillae is somewhat variable but in U. chavarriae the outer and inner ends of the row are equally distant from the field of apical setae, while in U. acosa the outer end is almost always farther from the apical setae than the inner end; the transverse dark bands on the abdomen are always well defined in U. acosa but usually small or lacking in U. chavarriae . Confirmed specimens of U. chavarriae are known only from the type locality, but small nymphs (all non­paratypes) collected in nearby streams in Sector Santa Elena may also belong to this species: 1 nymph, Quebrada Calera, L_N_356216­316528, 5–IX–2004, M M Chavarría Díaz; 13 nymphs, tributary of Río Potrero Grande, 3–XII–2004, S. Ávila, M.M. Chavarría, R.W. Flowers.