Cryptonympha tracheata Derka & Nieto, 2018

Derka, Tomáš & Nieto, Carolina, 2018, A new species of Cryptonympha Lugo-Ortiz & McCafferty (Ephemeroptera, Baetidae) from Cerro Duida (Venezuela), Zootaxa 4377 (4), pp. 587-592 : 588

Cryptonympha tracheata Derka & Nieto , new species ( Figs. 6–19 )

Nymph. Length (mm). Body: 2.9–3.1, cerci: 1.7 (n=6). Antennae broken. General coloration yellowish brown ( Figs 6– 7 ). Head yellowish brown, compound eyes orange brown, ocelli blackish. Antennae pale yellow. Mouthparts ( Figs 8– 13 ): Labrum ( Fig. 8 ) rectangular, broader than long, length about 0.7 times maximum width, distal margin with medial emargination; anterolateral margin with simple setae, distal margin with bifid setae apically, dorsal surface with 1 pair of submedial long and fine setae near midline, 1 similar pair of setae located more subapically and 1 pair of similar subapical shorter setae laterally. Left mandible ( Fig. 9 ): incisors partially fused apically, outer and inner set of incisors respectively with 3 + 3 denticles; prostheca robust with 4 denticles; margin between prostheca and mola straight, tuft of spine-like setae at base of mola; thumb of mola area subtriangular and in the same line to anterior margin, denticles of mola not constricted, lateral margins convex. Right mandible ( Fig. 10 ): incisors fused apically, outer and inner set of incisors respectively with 4 + 5 denticles; prostheca robust with 8–9 denticles and with a transverse robust and pectinate seta, margin between prostheca and mola convex and with a row of setae; denticles of mola not constricted, apex of mola with a simple seta, lateral margin of mola concave. Hypopharynx ( Fig. 11 ): lingua subtriangular with a medial lobe rounded, subequal to superlinguae; short and fine setae scattered over distal margin of lingua and superlinguae. Maxillae ( Fig. 12 ): posterior side of lacinia mediobasally with a row of 4–5 fine and short setae, basally to this row a single and longer seta; maxillary palpi 1.2 times the length of galea-lacinia, segment II at least two times the length of segment I. Labium ( Fig. 13 ): glossae subtriangular, basally broader, narrowing apically and subequal to paraglossae, outer margin with long spine-like setae, inner margin with robust spine-like setae, ventral surface covered by thin and long setae. Paraglossae subtriangular, acute apically, curved inward, outer and inner margins with long and robust spine-like setae, dorsal surface with a few short spine-like setae. Labial palpi with segment I, 1.1 times the length of segment II and III combined; segment II with rounded medial projection, outer margin and distomedial projection covered with fine and long setae; segment III conical, length 1.14 times width, covered by fine and simple setae on outer margin.

Thorax. Pro, meso and metanotum yellowish brown ( Figs 6–7 ). Pleurae yellowish, sterna pale yellow. Legs ( Fig. 14 ) pale yellow. Dorsal and ventral margin of femora with a row of short and robust spine-like setae, three spines apically. Ventral margin of tibiae and tarsi with a row of short and robust spines. Tarsal claws ( Fig. 15 ) with two rows of 11 and 13 denticles respectively. Abdomen yellowish brown ( Figs 6–7 ) and with scales (following Kluge, 1997). Posterior margin of tergum ( Fig. 16 ) with rounded spines, as long as it is wide. Gill I small, nearly half length of gill IV ( Figs 17–18 ). Gills II–VII ( Figs 6–7 , 18 ) long, 2.5 times the length of each tergum, whitish with trachea dark tinged. Paraprocts ( Fig. 19 ) with scales, and with 19–21 marginal spines, postero lateral extension with 10–12 spines. Caudal filaments with spines on each segments. Terminal filament as long as cerci, cerci basal 2/3 whitish, apical 1/3 brownish.

Etymology. The specific epithet is a Latin adjective meaning tracheate. It is in reference to the long tracheal gills with highly visible tracheae.

Diagnosis. The nymph of Cryptonympha tracheata sp. nov. can be distinguished from the other species of the genus by the following combination of characters. 1) posterior margin of terga ( Fig. 16 ) with rounded spines; 2) gill I small, nearly half length of gill IV ( Figs 17–18 ); 3) gills II–VII ( Figs 6–7 , 18 ) long, 2.5 times the length of each tergum; 4) segment II of maxillary palpi ( Fig. 12 ) at least two times the length of segment I.

Material. Holotype: female nymph ( IBN). VENEZUELA, Estado Amazonas, Caño Negro above La Culebra village , N 03°43´5.4´´, W 65°45´58.3´´, 854 m a.s.l., 25/XI/2013, T. Derka col. Paratypes ( IBN, MIZA and FNS): 10 nymphs same data as holotype.

Habitat. The specimens were collected on the slopes of Cerro Duida, in a black-water mountain stream, originating on the Cerro Duida plateau. The stream is 10 m wide, up to 1.5 m deep, with a temperature of 20.1 °C ( Figs 3–5 ). It is surrounded by a pristine montane forest. The stream bed is composed of bedrocks, rocks, boulders and scattered accumulations of sand and gravel. The bedrock bottom is frequently overgrown by macrophytes from the family Podostemaceae .

Figures

FIGURES 1–7. 1–2, map of study site location; 3–5, photographs of study site. Cryptonympha tracheata sp. n. Nymph. 6, dorsal habitus; 7, lateralview.

FIGURES8–19.Cryptonympha tracheatasp.n.Nymph.8,labrum,left d.v., rightv.v.; 9, leftmandible;10, right mandiblewithdetail of prostheca; 11, hypopharynx v.v.; 12, maxilla v.v.; 13, labium, left d.v., right v.v.; 14, fore leg; 15, fore tarsal claw; 16, posterior margin of tergumIV; 17, gillI; 18, gill IV;19, paraproct;scale = 0.24 mm.