In this paper, Smicridea (Rhyacophylax) repula Oláh & Johanson, 2012 is synonymized with Smicridea (R.) lobata (Ulmer, 1909), and the species Leptonema islamarga Botosaneanu, 2002 is transferred to Smicridea (R.) as a synonym of S. lobata. Additionally, we present more detailed illustrations of the male genitalia of S. (R.) lobata and S. (R.) signata (Banks, 1903), and include notes on their distributions to aid in the identification of these two, often-confused species.

Synonymy, New combination, Neotropics, Nearctic, Trichoptera

The genus Smicridea was established by McLachlan (1871) to include the species Smicridea fasciatella from Texas. The genus now contains 232 species, making it, by far, the largest Hydropsychidae genus in the Western Hemisphere. The genus occurs from the southwestern USA, through Mexico, Central America, the Caribbean, and all of South America. It is divided into two subgenera: the nominotypical Smicridea (130 species) and Rhyacophylax Müller 1879 (102 species); the subgenera are based mainly on differences in the wing venation (Flint 1974a).

In the subgenus Rhyacophylax, the signata group of Flint (1974a) is characterized by a fixed, tongue-like, ventromesal process on the apex of the phallus, and the presence of a lobe with spinose processes developed in various numbers and positions, arising from the ventrolateral margin of the tenth tergum. Sixteen species distributed from northern South America, throughout Central America, into southwestern USA (Arizona, Colorado, New Mexico, Texas, and Utah) are included in this group (Table 1).

Smicridea lobata (Ulmer 1909, in Ulmer and Thienemann 1909) was described from Las Trincheras (Venezuela), from a single male specimen preserved in alcohol. Ulmer mentioned that the forewing coloration of S. lobata resembled that of S. columbiana (Ulmer 1905), but he did not compare the genitalia of these two species or those of any of the species in the genus known at the time. Later, Flint (1974b) doubtfully recorded S. lobata from Surinam. Even though he did not examine the type, he stated that the specimens he studied agreed with the illustration of the type of S. lobata provided by Ulmer. Additionally, after carefully examining the type specimen of S. lobata, Flint (1978) concluded that the species he referred to as S. lobata in his earlier paper was actually a different species, which he described as S. pseudolobata, due to differences in the tenth tergum and the phallus.

Smicridea repula Oláh & Johanson, 2012 was described from Los Tuxtlas area in the state of Veracruz (Mexico). The authors included this species in the signata group, stating that it was closely related to the species S. lobata from Venezuela and S. nemtompa Oláh & Johanson, 2012 from Ecuador and Peru. They indicated that their new species was easily distinguished from S. lobata and S. nemtompa by having a lateral wing-shaped process at the mid-length of the phallus.

Leptonema islamarga Botosaneanu, 2002, in Botosaneanu and Viloria 2002, was described from Isla Margarita, Venezuela, and was placed in the L. davisi group of Flint, McAlpine and Ross 1987, based on characters of the male genitalia.

The species Smicridea signata (Banks, 1903) was originally described as Pellopsyche signata, from Fort Collins, Colorado (USA). The description was based on characteristics of the body and wings, with no genitalic characters included (the type is a female). Later, Ross (1944) transferred the species, as R. signatus, to Rhyacophylax, a separate genus at the time. More recently, Flint (1974a) redescribed the species as Smicridea (R.) signata, and illustrated the male and female genitalia as well as some features of the larva.

We conclude that S. repula and L. islamarga are synonyms of S. lobata, which is a separate species distinct from S. signata, based on differences in the tenth tergum as well as in their distributions. Herein, we provide justification for these taxonomic changes as well as more detailed illustrations of S. lobata from sites near the type locality (Fig. 1) and of S. signata from Utah.

Figure 1–2. 

Smicridea (R.) lobata (Ulmer, 1909) and Smicridea (R.) signata Banks, 1903, male genitalia. 1ASmicridea (R.) lobata segments IX and X, lateral 1B Left inferior appendage, ventral 1C Phallus, lateral 1D Phallus, dorsal 1E Segments IX and X, dorsal 2Smicridea (R.) signata. Segments IX and X, dorsal. These illustrations were made from specimens of S. lobata from Zulia and Sucre States, Venezuela, and specimens of S. signata from Utah, USA.

Specimens were examined with an Olympus SZH dissecting microscope (Olympus Corporation). The illustration of the male genitalia of S. lobata was prepared from pencil sketches made with the aid of a drawing tube attached to an Olympus BX41 compound microscope. The pencil sketches were scanned and placed into an Adobe Illustrator CS6 (Adobe Systems, Inc.) document to serve as a template to create a vector graphic illustration. The careful tracing of the original image was accomplished by using a graphic tablet and pen (BAMBOO, Wacom Technology Co.).

We carefully examined specimens from the type series of S. repula and L. islamarga, borrowed from the Swedish Museum of Natural History (Stockholm, Sweden) and the Naturalis Biodiversity Center (Leiden, The Netherlands), respectively. Further, we examined material of S. signata and S. lobata identified by Dr Oliver Flint (National Museum of Natural History, Smithsonian Institution, Washington D.C.) and Dave Ruiter (Grants Pass, Oregon, USA) as well as material from the University of Minnesota Insect Collection (St. Paul, Minnesota, USA), and the female type of S. signata from the Museum of Comparative Zoology, Harvard University, (Cambridge, Massachusetts, USA). The type of S. lobata at the Natural History Museum of Denmark (Copenhagen, Denmark) could not be found (H. Enghoff, pers. comm.).

The material examined is deposited in the following institutions:

DRC Dave Ruiter, personal collection, Grants Pass, Oregon, USA

NBC Naturalis Biodiversity Center, Leiden, The Netherlands

MCZ Museum of Comparative Zoology, Harvard University, Cambridge, Massachusetts, USA

NMNH National Museum of Natural History, Smithsonian Institution, Washington D.C., USA

NRM Swedish Museum of Natural History, Stockholm, Sweden

UMSP University of Minnesota Insect Collection, St. Paul, Minnesota, USA

Flint (1974a) stated that S. signata was easily recognized by the presence of a lateral serrate process (wing-shaped process of Oláh and Johanson 2012) and a pair of apicodorsal lobes in the phallus. However, after examining the type of S. lobata, Flint (1978) considered it and S. signata to have nearly identical phalli, including the aforementioned processes and lobes. Smicridea signata and S. lobata differ in the shape of the tenth tergum. In S. lobata the tergites are finger-like and have a bifurcate lobe of varying sizes from the ventral margin (paraproct of Oláh and Johanson 2012) (Fig. 1), whereas in S. signata the tergites are broader and the lobe from the ventral margin is rounded (Flint 1974a; fig. 138) (Fig. 2). Flint (1978) also mentioned that the tergites in S. lobata were widely separated dorsomesally whereas in S. signata, they were closer together. However, in some of the material available to us, the tergites in both species were separated roughly by the same distance. In addition to Fig. 2, the figures of S. signata provided by Flint (1974a, figs 137–140) can be used to separate this species from S. lobata.

Oláh and Johanson (2012) mentioned that the diagnostic character that separates Smicridea repula from its closest relatives, S. lobata and S. nemtompa, is the presence of lateral serrate processes at the mid-length of the phallus. However, as Flint (1978) noted, both S. signata and S. lobata also have these processes. Additionally, the illustration accompanying Oláh and Johanson’s description for S. repula matches Ulmer’s S. lobata illustration perfectly (Ulmer and Thienemann 1909; fig. 2). Also, the S. repula holotype that was loaned to us fits perfectly with the examples of S. lobata from Costa Rica, Guatemala, Mexico, Nicaragua, Panama, and Venezuela from the Smithsonian and the University of Minnesota Insect Collection. In these examples, the lateral serrate processes of the phallus vary in size, as noted by Flint (1974a) also for S. signata. Finally, since the serrate processes of the phallus are not exclusive to S. repula, and all the other characters between S. repula and S. lobata perfectly match, we consider S. repula Oláh & Johanson, 2012 to be a junior subjective synonym of S. lobata (Ulmer, 1909), new synonym.

Botosaneanu and Viloria (2002) provided a combination of characters for the inclusion of Leptonema islamarga in the L. davisi species group, along with L. aterrimum Mosely, 1933, L. davisi Flint, McAlpine & Ross, 1987, and L. gadzux Flint, McAlpine & Ross, 1987. However, most of the proposed characters for the inclusion of L. islamarga in this group are rather general (e.g., small size, tibial spur formula 1/4/4, middle tibia of females not dilated, and phallus with processes), and they are not exclusive of the group, much less to the genus Leptonema. The authors also mentioned that the forewing pattern of L. islamarga was extremely distinctive from other members of the genus Leptonema. After comparing the forewing color pattern of the paratypes (fig. 7 of Botosaneanu and Viloria 2002), and other specimens, we conclude that this forewing coloration actually corresponds to the color pattern and venation found in many species of Smicridea (Rhyacophylax). Additionally, Botosaneanu and Viloria (2002) observed a pair of gill-like appendages from the fifth sternite in both sexes. They also hypothesized that these structures replaced the raised, glandular structures of Leptonema. However, these structures actually correspond to the anterolateral filaments commonly present in the subgenus Rhyacophylax (Flint, 1974b). Finally, the authors recognized that the male genitalia of L. islamarga were quite distinct from the other three species in the Leptonema davisi group, except for the absence of warts on the tenth abdominal tergum. The illustrations of Leptonema islamarga and the specimens in the type series match perfectly with the specimens we have examined of S. lobata and with Ulmer’s illustration of S. lobata. Accordingly, Leptonema islamarga Botosaneanu, 2000 is transferred to the genus Smicridea (Rhyacophylax) and placed as a junior subjective synonym of Smicridea lobata (Ulmer, 1909), new combination, new synonym.

Based on the material examined, Smicridea lobata is distributed in Mexico, Guatemala, Honduras, El Salvador, Nicaragua, Costa Rica, Panama, and Venezuela, and S. signata is distributed in southwestern USA, Mexico, and Guatemala. Flint (1974a), in his redescription of S. signata included several specimens that were actually S. lobata. After re-examining this material, we noted that the distributions of S. lobata and S. signata overlap in Mexico and Guatemala. Furthermore, we observed that along with the lateral serrate processes of the phallus, the ventrolateral lobes of the tenth tergum tend to increase in size towards the southern portion of its range. However, as Flint (1974a) stated, these two species can be readily distinguished by the shape of the tenth tergum in dorsal view (Figs 1E–2). The ventrolateral lobes of the tenth tergum are bifurcate in S. lobata and rounded in S. signata, and the dorsomesal processes are finger-like in S. lobata and broad in S. signata. Additionally, the ventrolateral lobes of the tenth tergum in S. signata present a very small spicule apically, which was not illustrated by Flint (1974a).

The authors would like to thank the curators and institutions that loaned the material used in this study: Dr Oliver S. Flint, Jr. (NMNH), Dr Willem Hogenes (NBC), Dr Tobias Malm and Dr Kjell Arne Johanson (NRM), Dr Philip Perkins and Rachel Hawkins (MCZ), and Dave Ruiter (Grants Pass, Oregon, USA). ERG would also like to thank Dr John Luhman for translating the German text in the original description of Smicridea lobata. Dave Ruiter and Dr Brian Armitage provided helpful comments to improve the manuscript. This paper was prepared thanks to a doctoral fellowship from Cienciactiva, initiative from Consejo Nacional de Ciencia, Tecnología e Innovación Tecnológica, Peru (contract 277-2015-FONDECYT) awarded to ERG. The research was conducted with the support of Minnesota Agricultural Experiment Station projects MN 17-017 and MN 17-029. This support is gratefully acknowledged.