New species and records of Cloeodes Traver, 1938 (Ephemeroptera, Baetidae) from Costa Rica

Abstract The nymph of Cloeodes dantasp. nov. is described from male and female nymphs collected from highland streams in the Caribbean Slope of the Costa Rica Central Volcanic Mountain Range. Adults are unknown. In addition, C. excogitatus and C. redactus are recorded for the first time in the country. Cloeodes dantasp. nov. can be differentiated from all described species by the predominantly brownish coloration on females and a similar coloration on males but with segments VII–IX light yellow and light brown, with no conspicuous marks or patterns; abundant scale-bases throughout most parts of the body; hindwings pads absent; the presence of three spines in the corners of the posterior margin of sternum III, and the posterior margin of tergum III with 28–30 spines on each side of the middle line (spine with a base width up to 0.5× spine length).

Body coloration: Brownish in general ( Fig. 2A, 2B), the head light brownish, with clearer area from central ocelli to the border of clypeus and between antennal and labrum bases; ocelli black, with two tiny white symmetrical dots on each side and clear brownish coloration, darker toward ocellus; eyes black, turbinated portion of compound eyes brownish. Fore wing pads brownish, foreleg brown with slightly lighter areas. Abdomen with even brownish coloration on females and males with predominantly brownish color but with segments VII-IX light yellow and light brown, both with no patterns of marks or spots, and upper corners of abdominal segments darkened; terga I-VIII with visible black posterior sigilla in the middle of every segment, terga VII-IX lighter with upper corners darkened; sterna pale yellowish-brown.
Head (Fig. 3A): Capsule longer than wide. Antennae subequal to 1.3× length of head, with scape subequal to 1.3× times length of pedicel (Fig. 3B). Intra-antennal extension of frons prolongs to ocelli. Labrum (Fig. 3C). Subrectangular, broader than long, anterolateral margins rounded; dorsally with anterior margin with about 20 small, double frayed setae. Lateral margin with eight apically frayed setae; arc of anterodorsal setae with four simple setae; intermediate seta tiny; and several small scattered simple setae near posterior margin. Ventrally with small curved fine setae near anterior margin, and seven small simple setae near lateral margin. Anterior margin slightly asymmetric, with the left side of the cleft not extended the same length as the right side ( Fig 3D).
Left mandible (Fig. 4A). Incisors with seven denticles, middle one reduced and others similar in size; prostheca robust, apically with three lobes and four elongated projections. Row of 5 or 6 minute spine-like setae between prostheca and molar region, only visible at high magnification (40×). Ventral surface of molar region with tuft of spines next to thumb as part of molar structure (Fig. 4B). Right mandible (Fig. 4C). Incisors with seven denticles, middle one reduced and others similar in size; prostheca with broad base, bifid, inner projection longer, and both parts frayed; 3-4 tiny, simple setae between prostheca and molar region only visible at high magnification (40×); tuft of spines next to molar region.  Hypopharynx (Fig. 4D). Lingua rounded with no apical lobes, slightly longer and broader than superlinguae, both apically covered with short fine hairs on dorsal and ventral surface.
Maxillae (Fig. 4E). Palpi slightly shorter or as long as galea-lacinia, two segmented; segment I slender in mid part; segment II 1.4× length of segment I; both segments with several simple short setae. Crown of galea-lacinia without thick distal dentisetae, with numerous setae on the inner-dorsal and inner ventral rows, and longer and slender towards the biting edge; medial region of galea-lacinia with one short seta and 5 or 6 long, simple setae. Labium (Fig. 5A). Glossa and paraglossa similar in length, basally broad and apically narrow; with the base of the glossa reaching more than half of the paraglossa; glossae dorsally with 7-8 setae next to the inner margin and some scattered setae, ventrally with 12 or 13 setae on the inner margin and 9 or 10 on the outer margin, increasing in length apically in both cases. Paraglossae curve inwards, apex subtriangular, dorsally with 7 or 8 setae on the inner margin and 17 or 18 setae on outer margin. Palpi with segment I broad and 0.8× length of segment II and III combined, numerous micropores and simple, tiny setae on both dorsal and ventral surfaces; segment II with row of 6 or 7 setae on the dorsal surface; segment III suboval, dorsally with several short simple setae on apex and 20-25 simple setae of different size on the ventral surface, and the inner margin subequal to the outer margin.
Thorax: Hindwing pads absent; foreleg with abundant scale-bases and scattered micropores (Fig. 5B). Femur length about 4× maximum with; dorsal edge with 10 or 11 short, simple setae, ventrally bare, apex rounded with no evident projections, and two concave and apically rounded setae. Tibia with two lines of fine hairs arranged parallel to each other along the tibia, subtending bristle elongated and rounded (Fig. 5B, C). Tarsi dorsal edge bare, ventrally with 10 or 11 minute spines, increasing in size distally; tarsal claw length 0.5× length of tarsi. Mid and hind legs are similar to the foreleg.
Abdomen: Gills ( Fig. 6A-G). Present on segments I-VII, colorless, oval, margins with curved fine setae (Fig. 6D, 6E); light-brown tracheae extending from main trunk, branching to margins. Gill I smaller than segment II; gill IV length about 1.3× length of segment III; gills on segment VII not extending beyond apex of segment X ( Fig. 2A, B).
Terga. Tergum I with no spines on posterior margin; tergum III with 28-30 spines on posterior margin of each side of the middle line, spine bases almost same width as height (Fig. 6J).
Sterna (Fig. 6I). Posterior margin of sternum III with group of 26-28 variable size spines on each side of middle line, spines bases width about one-third of height; group of fine hairs arranged in slightly curved line on each side of sterna and three thick spine-like teeth on each corner of posterior margin of sternum III (Fig. 6H).
Paraprocts (Fig. 6K). Lateral margin with 13-15 spines, different in size and arranged in irregular line, with some overlapping; dorsal surface with numerous micropores and scale-bases; posterolateral extension with about 11 or 12 marginal spines, and several scale-bases and micropores.
Etymology. The name of this species honors the Danta (Tapirus bairdii) (Mammalia: Tapiridae), a common species in the Cerro Chompipe cloud forest zone, whose three-toed back feet resemble the sternal spine-like teeth described as a diagnostic character of C. danta sp. nov. Distribution. Costa Rican, Caribbean slope basin, first order streams, above 2000 m asl.
Biology. Habitat preferences in C. danta sp. nov. were observed in relation to elevation. Individuals were found at 2054 m asl in cold waters of two cloud forest streams (Fig. 7); other non-Andean species have been reported between 159-1800 m asl (Nieto and Richard 2008;Gutiérrez and Reinoso-Flórez 2010;Massariol and Salles 2011;Massariol et al. 2013;De Paul et al. 2013;Gutiérrez and Dias 2015). Also, the new species was collected in a pristine forest region, which may be similar to other Cloeodes species in Brazil that seem to prefer remnant forest areas (Salles et al. 2015). In addition, C. danta sp. nov. is common in riffles, on igneous boulders that are covered with periphyton; this is typical for this genus, part of the grazer functional feeding group (Baptista et al. 2006).

Discussion
Cloeodes danta sp. nov. shares morphological affinities with the following species: C. caraibensis Hofmann et al. 1999, C. excogitatus, C. redactus, andC. maculipes Traver, 1938, including, absence of hind wing pads, segment III of labial palp rounded, maxillary palp shorter than galea-lacinia, and the general shape of other structures like labrum, labium and the apex of the femur that were recognized by Hofmann et al. (1999) and Nieto and Richard (2008). Based on the material and literature reviewed, we consider that Central American and Caribbean species can be separated in two groups according to the depth of the central cleft on the right mandible incisives: in C. excogitatus and C. redactus the cleft breaks down below the level of mandible first inner incisor apex (Waltz and McCafferty 1987: fig. 27;Kluge 2017: fig. 66), while in C. danta sp. nov., C. caraibensis and C. maculipes the cleft breaks down at the level of the first inner incisor apex (Waltz and McCafferty 1987: figs 3, 4 ;Hofmann et al. 1999: fig. 37; Fig. 4C).
In regard to C. caraibensis from Lesser Antilles, these species mentioned above have setae on segment III of the labial palp as long as the setae on the glossa and paraglossa (Waltz and McCafferty 1987: fig. 6;Hofmann et al. 1999: fig. 41), while in C. danta these setae are shorter (Fig. 5A). Also, labrum intermediate setae are well developed in C. maculipes (Waltz and McCafferty 1987: fig. 2), while in C. danta sp. nov. they are minute (Fig. 3C); in regard to C. caraibensis this character is absent, and this species also shares some diagnostic characters with C. danta sp. nov. like scale-bases present on most of the body, shape of III segment of labial palp and spines on the corner of the posterior margins of the sterna (Hofmann et al. 1999: figs 36, 41, 50); however, C. danta sp. nov. can be differentiated by no spots or color pattern on the abdomen, right mandible prostheca with two well-developed branches, glossa apically not lobulated, distal portion of gills rounded, minute spines on the terga and sterna margins, and the posterior margin of the paraproct with no bifurcated spines (Figs 2A, 2B, 4C, 4D, 6A-6G, 6K).
Furthermore, C. danta sp. nov. shares similar features with C. excogitatus, such as the number of spines in the terga III, the shape segment III of labial and the abundance of setae on it (20-25), the number of spines in the paraproct, and body size (Waltz and McCafferty 1987, but C. danta sp. nov. can be identified by the different abdominal color pattern, abundant scale-bases throughout most parts of the body, the maxillar palp is equal in length to the galea-lacinia and the absence of a narrow intra-antennal extension. Also, the new species resembles C. redactus in the length of the maxillary palp being about as long as the galea-lacinia, the number of spines in the paraproct and the lack of any projections on the apex of the femur (Waltz and MacCafferty 1987;Kluge 2017); however it could be distinguished by the shape and number of spines in terga III, the absence of the colorless spots in some terga, a larger body size, the presence of an intermediate setae on the labrum, and the presence of thick spine-like teeth in the inferior corner of sterna III.
In order to improve the identification of Cloeodes species in the Central American region, we provide a key to distinguish C. danta sp. nov., C. excogitatus and C. redactus. This will be a useful tool for future aquatic research in the region, which has been increasing over the last 20 years due to development of water quality monitoring using aquatic insects (Alonso-Eguía et al. 2014;Carrie et al. 2017;Castillo 2018;Dávila-Recinos et al. 2019;Pérez 2019). Abdominal coloration on terga I-III and V-VII with 3 pale spots (the middle spot being smaller); intra-antennal extension narrow, labrum arc of anterodorsal setae with 5 simple setae; segment III of labial palp ventrally with 20-25 setae; maxillary palp shorter than galea-lacinia; 30-35 spines on tergum III (Fig. 8B

Acknowledgments
We thank our team at the Laboratorio de Entomología (LEUNA) (Carlos Esquivel, David Romero, and Francisco Bravo) for their help both in the field and in the lab with their companionship. We also thank the Escuela de Ciencias Biológicas from Universidad Nacional for their financial and logistical support. We are also grateful with Luke Jacobus (Division of Science, Indiana University Purdue University Columbus for the comments in the early draft, and Sudeep Chandra (Aquatic Ecosystems Laboratory University of Nevada Reno) for facilitating a space to examine part of the material.