New Baetidae (Insecta: Ephemeroptera) Records from Venezuela and Nymph Description of an Unnamed Fallceon Species
The Ephemeroptera fauna in Venezuela is poorly known, as is also the case in others areas in South America. Recently, two studies increased from 33 to 50 the number of species recorded in Venezuela. The objective of the present study is to report for the first time in Venezuela the following species: Baetodes levis; Camelobaetidius edmundsi; Fallceon sp.; Mayobaetis ellenae. The nymph of Fallceon sp. is described, but is not named because adults were not reared to allow species identification; however, description of this nymph indicates the presence of this genus in South America.
The Ephemeroptera of Venezuela is poorly known , it has been characterized as mega-diverse based on studies of the flora and fauna of the Caribbean, Andes, Amazon and Guiana regions . Until 2001, mayfly records for Venezuela represented only about 5% of the nominal mayfly species known in South America . The most recent estimate of species richness indicates Venezuela has about 9% of the mayflies in the Neotropics . The gap in faunal composition reflects the history of collecting rather than the actual richness of this taxon . Based on the number of published studies on mayflies in South America, it is obvious that there has been more collecting effort in Brazil and Argentina than in any other country in this region . In the last decades, a few studies have helped to increase our knowledge of Venezuelan mayflies (e.g., [5–7]). Recently, Nieto et al.  and Molineri et al.  studied Ephemeroptera in Venezuela’s Guyana Uplands, and in two articles the number of species recorded in the country increased from 33 to 50, reinforcing the need to increase the sampling area in order to really document the Ephemeroptera diversity in this country.
The lack of information of this nature makes the analysis of biogeographic patterns difficult and precludes the development of regional identification keys and systematic studies. To improve our knowledge of mayflies of Venezuela, the main objectives of this paper are (1) to report for the first time the following taxa from Venezuela: Baetodes levis Mayo; Camelobaetidius edmundsi Dominique, Thomas & Mathuriau; Fallceon sp. and Mayobaetis ellenae (Mayo) and (2) to describe the nymph of Fallceon sp.
2. Material and Methods
Nymphs were collected with an aquatic entomological net and fixed in 80% ethanol.
Formula for denticles of the mandible incisors has the following pattern: Number of denticles of outer incisor + Number of denticles of inner incisor.
Formula for setae of the maxilla medial protuberance has the following pattern: Number of setae on ventral surface + Number of setae on dorsal surface.
Permanent slides were prepared using Euparal as mounting media, and no tissue preparation was used, being dissected and inserted in Euparal immediately.
The drawings were made using a ZEISS Standard 20 microscope with a camera lucida. The examined specimens were deposited in the following institutions: Instituto Nacional de Pesquisas da Amazonia (INPA), Manaus, AM, Brazil and Instituto de Altos Estudios “Dr. Arnoldo Gabaldón”-IAE, Maracay, Aragua, Venezuela.
3.1. Baetodes levis Mayo 1968
3.1.2. Material Examined
Two nymphs (mouth parts, legs, antenna, cercus, terminal filament, paraproct, and gills on slide), Venezuela, Turmero, Paya Arriba, Municipio Mariño, Estado Aragua, rifles, above rocks, N10°18′24.2′′ W067°24′54.9′′, 765 meters, 17.iv.2011, N. Hamada, H. Frontado, C. Quinto, and U. Neiss leg. (INPA, IAE).
3.2. Camelobaetidius edmundsi Dominique, Mathuriau & Thomas 2001
Colombia (Dominique et al. ); New Record: Venezuela.
3.2.2. Material Examined
One nymph (mouth parts, legs, antenna, cercus, terminal filament, paraproct and gills on slide), Venezuela, Turmero, Guayabita, municipio Mariño, Estado Aragua, rifles, above rocks, N10°18′03.1′′ W067°28′24.5′′, 634 m, 17.iv.2011, N. Hamada, H. Frontado, C. Quinto, and U. Neiss leg. (INPA).
Camelobaetidius edmundsi is closely related to C. mathuriae Dominique & Thomas. However, the nymphs of the first species can be distinguished by the presence of thoracic gill at the base of the forecoxa, while in C. edmundsi, this gill is absent.
3.3. Mayobaetis ellenae (Mayo 1973)
Baetis sp. 1 Roback : 137. Baetis ellenae Mayo : 285; Berner : 190. Moribaetis (Mayobaetis) ellenae; Waltz and McCafferty : 240. Mayobaetis ellenae; Lugo-Ortiz and McCafferty : 369; Domínguez et al. : 163; Dias et al. : 238.
3.3.2. Material Examined
Four nymphs (one with mouth parts, legs, antenna, cercus, terminal filament, paraproct, and gills on slide), venezuela, Turmero, Paya arriba, Municipio Mariño, Estado Aragua, N10° 18′ 24.2′′ W067° 24′ 54.9′′, 765 meters, 17.iv.2011, N. Hamada, H. Frontado, C. Quinto, and U. Neiss leg. (INPA, IAE).
The collected nymphs have variations in the external mandible incisors, which are rounded, whereas in the original description they are blade-like. The differences observed in incisors are probably caused by natural abrasion with the substrate, which is probably a result of feeding behavior. Our specimens have classic body color pattern as illustrated by Mayo  and darker.
The nymph examined allowed placing it in the genus Fallceon by the following characteristics: (1) frontal keel present or absent; (2) incisors of mandibles fused; (3) right mandibles with a tuft of setae between the prostheca and mola; (4) base of glossa extended, at least, to the half of the base of paraglossa; (5) segment II of labial palp without distomedial process; (6) segment II of labial palp with a dorsal row of spine-like setae; (7) absence of villopore; (8) hind wing pads present; (9) claw with one row of denticles; (10) subapical setae on tarsal claw present or absent; (11) posterior margin of terga with pointed spines; (12) dorsal surface of terga with scale bases; (13) gills present on abdominal segments I to VII.
The Fallceon sp. V1 nymph examined differs from the other described species with known nymphs in the genus (e.g., González-Lazo and Salles, , Kluge , and Lugo-Ortiz et al. ) by the following combination of characteristics: Nymphs: (1) frontal keel present; (2) maxillary palp reaching apex of the galea-lacinia (Figure 1(e)); (3) left mandible with incisors completely fused (Figure 1(d)); (4) paraglossa narrow and pointed apically; (5) tarsal claw without subapical setae (Figure 2(a)); (6) abdominal terga I, VIII, IX, and X lighter; (7) gill IV as long as the length of segments V to half VI combined; gill VII as long as the length of segments VIII to IX combined; (8) paraproct with 10–14 marginal spines (Figure 2(d)).
3.4.2. Mature Nymph Description
Body length: 3.3 mm ().
Antenna (Figure 1(a)) brownish yellow with spines and fine, simple setae on apex of each segment; lateral branch of epicranial suture sinuous; frontal keel present. Labrum (Figure 1(b)) narrow apically, as broad as long; length about 0.8 × maximum width; distal margin with shallow medial emargination; lateral and anterolateral margins with long, branched setae; medial margin with robust bipectinate setae; dorsally with long, fine, simple setae scattered over surface; ventrally with row of short, spine-like setae near anterolateral margin. Right mandible (Figure 1(c)) with incisors completely fused; outer and inner set of incisors, respectively, with 4 + 4 denticles; prostheca robust, apically denticulate; margin between prostheca and mola slightly convex, tuft of setae present; tuft of spine-like setae at base of mola present; tuft of setae at apex of mola present, reduced to a single seta; lateral margins almost straight; basal half bare dorsally. Left mandible (Figure 1(d)) with incisors complete fused; outer and inner set of incisors, respectively with 4 + 3 denticles; prostheca robust, apically denticulate and with comb-shaped structure at apex; margin between prostheca and mola slightly convex, tuft of setae absent; tuft of spine-like setae at base of mola present; subtriangular process narrow, at same level as area between prostheca and mola; tuft of setae at apex of mola absent; lateral margins almost straight; basal half bare dorsally. Hypopharynx (Figure 1(f)), lingua with simple setae distally; superlingua longer than lingua. Maxilla (Figure 1(e)) with crown of galea-lacinia with 4 denticles; double rows of setae with bifid and pectinate dentisetae. Medial protuberance of galea with 1 + 3 spine-like setae. Maxillary palp reaching apex of galea-lacinia; palp segment II 0.9 × length of segment I; setae on maxillary palp fine and simple setae scattered over surface. Labium (Figure 1(g)) with glossa basally broad, narrowing apically and shorter than paraglossa; inner margin with eight spine-like setae increasing in length apically; apex with two spine-like setae; outer margin with seven long spine-like setae; ventral surface scattered with short, fine, simple setae; paraglossa curved inward, narrow and pointed apically, dorsally with apex with five long spine-like setae, outer margin with one row of long spine-like setae, inner margin with four long spine-like setae, ventrally with one row of long spine-like setae. Labial palp with segment I 0.7 × length of segments II and III combined; segment I covered with microspores and fine and simple setae; segment II without distomedial protuberance, dorsally with row of five spine-like setae; segment III conical, length 0.9 × width, covered with spine-like simple setae and fine, simple setae along margins, ventral surface covered with short spine-like setae.
Hind wing pads present. Foreleg (Figure 2(a)) brownish yellow, femur apically dark. Forefemur length about 2.7 × maximum width, dorsally with row of long blunt setae (in lateral view they resemble spine-like setae); length of setae about 0.2 × maximum width of femur; ventrally with micropores and few small, fine, simple setae; anterior surface with robust spine-like setae near ventral margin. Foretibia dorsally with many short, fine, simple setae; ventrally with one row of short spine-like setae, anterior surface with few robust spine-like setae; tibiopatellar suture present at base. Foretarsus dorsally with few, fine, and simple setae; ventrally with one row of spine-like setae. Foretarsal claw with one row of 11 denticles increasing in size distally, without subapical setae. Mid and hind legs are similar to the fore leg except for the dorsal margin with one row of small spine-like setae and hind tarsal claw with 13 denticles.
Segments I, VIII, IX, and X lighter. Terga surface (Figure 2(b)) with scale bases, posterior margin with spines basally broad and apically pointed; posterior margin of segments with spines: II–X. Sterna surface bare. Gills (Figure 2(c)) oval, margin with narrow spines alternating with short, fine, and simple setae; tracheae extending from main trunk to inner and outer margins. Gill I is subequal in length to segment II. Gill IV as long as length of segments V to half VI combined. Gill VII as long as the length of segments VIII to IX combined. Paraproct (Figure 2(d)) with 10 marginal spines; surface with scale or scale-bases; posterolateral extension with marginal spines. Cercus (Figure 2(e)) with spines on all segments. Terminal filament (Figure 2(f)) segments with spines on all segments.
3.4.3. Material Examined
One nymph (mouth parts, legs, antenna, cercus, terminal filament, paraproct, and gills on slide), Venezuela, Aragua, Municipio Zamora, Parroquia Magdaleno stream 7.5 km after Magdaleno, before Guacamaya, fine sediment and leaves on moderate current, stream no more than two meters wide, N10° 04′ 08.3′′ W067° 39′ 15.7′′, 579 m, 10.iv.2011, N. Hamada, H. Frontado, C. Quinto, and U. Neiss leg. (INPA).
Waltz and McCafferty  established the genus Fallceon for some species previously described in Baetis Leach, recorded from North and Central America. Lugo-Ortiz and McCafferty  transferred three South American species placed in Baetis to Fallceon based on the study of subimagos and imagos. Later, McCafferty  proposed Fallceon inops (Navás) as nomen dubium. In all of these papers, the adult character used to place the species in Fallceon was the shape of the hook on the costal process of the hind wing. Considering that most of the useful features for taxonomic study in Baetidae are found in the nymphs [27, 28], discussions about species based solely on adults are difficult. In this study, we present the first record and description of a nymph of Fallceon from South America. The species was described but not named because we were not able to rule out the possibility that is one of the two species of Fallceon that had been previously described based on imagos from South America. However, the collection of this nymph indicates the presence of Fallceon in South America. This description will aid in future studies on immature adult associations for the genus in South America.
Fallceon sp. V1 and F. testudineus Kluge  are similar; Fallceon sp. has the labrum narrowed apically and glossa shorter than paraglossa, while F. testudineus has labrum not narrowed apically and glossa subequal in length to the paraglossa.
The authors thank Dr. Nikita Kluge, Dr. Frederico Salles, and Dr. Neusa Hamada for all the help offered during the preparation of this paper, Dr. Philip M. Fearnside for reading the paper, and the valuable suggestions of the anonymous reviewer. The Instituto de Altos Estudios “Dr. Arnoldo Gabaldón” IAES-MPPS provided support for the fieldwork; laboratory support was provided by research projects supported by PRONEX-CNPq-FAPEAM/INPA (MCT), PCI/MCT/CNPq and CNPq-Neusa Hamada fellowship, and Protax (CNPq) number 52/2010.
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