Corresponding author: Crystal A. Maier (
Academic editor: Terry Erwin
Here we describe a new genus, for a new species of riffle beetle,
Se describe un género nuevo, para una especie nueva de Elmidae,
The Elmidae are a cosmopolitan family of beetles common in a variety of running water habitats. They are known for their “leggy” appearance, with long legs and claws that aid in clinging to rocks and other detritus in fast-flowing water. Members of the subfamily Larainae are atypical among the riffle beetles, as the adults do not live submerged, but on water-splashed rocks and in moist detritus at the water’s edge.
Currently, there are 26 genera of laraines described, with ten occurring in the Neotropical Region. The Central American and West Indian fauna was revised in 1991 by Spangler and since then, two other genera have been described from the tepuis of southern Venezuela,
Specimens of the new genus described here were collected from Cerro de la Neblina, the “Mountain of the Mists” in southeastern Amazonas State, Venezuela (
Map of Venezuela, showing collection localities for
Specimens of this new taxon were collected during a biological survey of Cerro de la Neblina in 1985. They were photographed using a Canon EOS 70D with a Visionary Digital imaging system and photos were stacked using CombineZM image editing software.
For scanning electron micrographs, the specimen was dehydrated in 100% ethanol and cleaned with an insect pin and fine brush. The specimen was then affixed to an SEM stub using carbon tape and coated with gold. Micrographs were taken using a Leo 1550 Scanning Electron Microscope at the Microscopy and Analytical Imaging Laboratory at the University of Kansas.
The genitalia were extracted from relaxed specimens through the caudal opening in the abdomen. The genitalia were then cleared in heated potassium hydroxide for thirty minutes, rinsed with water, and temporarily mounted in glycerin for observation and illustration. The cleared genitalia were then placed in a glass genitalia vial below the specimen for storage.
Hind wings were removed and dry mounted on slides using methods outlined in
Museo del Instituto de Zoología Agrícola Maracay, Venezuela
La Universidad del Zulia, Maracaibo, Venezuela
National Museum, Prague, Czech Republic
Naturhistorisches Museum, Vienna, Austria
Snow Entomology Collection, University of Kansas, Lawrence, Kansas, USA
Smithsonian Institution, Washington, DC, USA
This genus can be distinguished from all other laraine genera by its small size (ca. 4.5 mm), and the presence of a shallow, wide, V-shaped groove across apical third of the pronotum (
Body elongate, form gradually widening to posterior two-thirds of elytra then converging to elytral apex, moderately convex (
Head capable of being partly retracted into prothorax but not beyond the basal portion of the submentum (
Pronotum widest at base, weakly sinuate laterally, becoming evenly arcuate over head; base trisinuate, broadly sinuate on each side and much more narrowly so immediately anterior to scutellum; anterolateral angles explanate and broadly depressed; posterolateral angles slightly explanate, declivous, not depressed; middle of base with two short, broad, prescutellar cariniform ridges, each ridge with distinct lateral depression (
Hind wing lightly pigmented. Radial bar strong; radio-medial loop and radial cross vein r4 distinct; radial cell incomplete; medial fleck absent; media posterior MP1+2 strong, distinct; medial spur long, nearly reaching wing margin; first and second cubito-anal cells present; medial field with five free veins reaching margin (medial spur not included); anal field with single vein; apical field with two lightly pigmented bands (
Abdomen with five ventrites. First ventrite with paired, broad carinae posterior to metacoxae extending almost to hind margin of ventrite (
This new genus keys to couplet 4 in Brown’s (1981) key to the world genera of the elmid subfamily Larainae. Since Brown’s key was published, four new genera of Larainae have been described from the Western Hemisphere:
1 | Body size smaller, length 2.5 to 4.5 mm | 2 |
1' | Body size larger, length 5.1 to 10.1 mm | 6 |
2(1) | Elytron with one accessory basal stria. Chile and Argentina | |
2' | Elytron without an accessory basal stria | 3 |
3(2') | Pronotum with a deep transverse groove across apical third (see Spangler and Santiago 1992: Fig. 5) | 5 |
3' | Pronotum without a transverse groove, or with a shallow, wide, V-shaped groove across apical third ( |
4 |
4(3') | Pronotum with a shallow, wide, V-shaped groove across apical third ( |
|
4' | Pronotum without a transverse groove (see Spangler and Santiago 1992: Fig. 3). Texas, USA, south to Peru, Greater Antilles | |
5(3) | Pronotum with a median groove and without small prescutellar foveae; anterolateral angles of pronotum rounded (see Spangler and Santiago 1992: Fig. 4). Costa Rica, south to Venezuela | |
5' | Pronotum without a median groove and with two small prescutellar foveae; anterolateral angles of pronotum declivous (see Spangler and Santiago 1992: Fig. 5). Mexico, south to Peru and West Indies | |
6(1') | Elytron with one accessory basal stria. British Columbia, Canada and Pacific Northwestern United States | |
6' | Elytron without an accessory basal stria | 7 |
7(6') | Elytron with distinct longitudinal carinae (see |
|
7' | Elytron without distinct longitudinal carinae | 8 |
8(7') | Pronotum with a distinct transverse groove across apical third | 9 |
8' | Pronotum without a transverse groove across apical third (see Spangler and Santiago 1992 Fig. 8). Costa Rica, south to Peru | |
9(8) | Pronotum with a lateral longitudinal carina or arcuate-sinuate groove on basal third | 10 |
9' | Pronotum without a carina or arcuate-sinuate groove on basal third | 11 |
10(9) | Pronotum with two prescutellar mammiform tubercles at base and one similar tubercle near each posterolateral angle, thus appearing bidentate (see Spangler and Santiago 1992: Fig. 6). Panama, south to Ecuador | |
10' | Pronotum with two short, converging, prescutellar carinae, each with a deep pit laterally (see Spangler 1989: Fig. 9). Venezuela | |
11(9') | Body narrow. Prosternal process sagittate, tapering gradually to apex (see Spangler and Santiago 1992: Fig. 215). Hispañola | |
11' | Body broad. Prosternal process ligulate at apex (see Spangler and Santiago 1987: Fig. 128). Argentina and Brazil |
Holotype male: “VENEZUELA: T. F. AMAZ./ Cerro de la Neblina/ Camp XI 1450 m/
Other Material Examined: “VENEZ., T.F.A./C.d.l. Neblina/Base camp/26–31 Jan. 1985/Flite [sic] intercept Pan/Trap” (1 male). “VENEZUELA: T. F. AMAZ./ Cerro de la Neblina/ Camp X, 1690m/
Monotypic genus – see generic diagnosis.
Holotype Male. Body elongate, subparallel, dorsum moderately convex. Length, 4.4 mm; greatest width, 2.0 mm. Body dark brown dorsally; venter light reddish brown, except elytral epipleura, metepisternum, lateral margins of abdominal ventrites 3–5 dark brown. Antenna, maxillary palpus, labial palpus, labium, maxilla, coxa, trochanter, basal four-fifths of profemora and mesofemora lighter reddish-brown. Dorsal and ventral surface densely covered with recumbent setae (
Head moderately coarsely, densely punctate; punctures separated by their diameter; cuticle microreticulate. Eye hemispherical, bordered with row of long, curved setae (
Pronotum 1.4 mm long, 1.5 mm wide; with deep sinuate sublateral groove, which extends from apical third of pronotum to base; lateral margins slightly sinuate; anterolateral angles obtuse, distinctly explanate and broadly depressed behind each angle; apex slightly sinuate and with broad lobe medially; posterolateral angles obtuse, slightly explanate, declivous, not depressed adjacent to each angle (
Prosternum very long in front of procoxae; bearing a tuft of sparse, long, dark brown setae and dense golden setae apicomedially. Prosternal process (
Elytron with ten rows of coarse, very deep punctures (
Abdomen with five ventrites (
Aedeagus with parameres straight and wide (
Similar to male, except lacks the patch of longer setae apicomedially on prosternum and the patch on each side of median groove on apical third on metasternum. Genitalia as illustrated (
As noted in the “Remarks” section, the shape of the parameres of the aedeagus vary from straight and wide to narrow and curved. This species exhibits only minor variations in length, which ranges from 4.2 to 4.5 mm, and varies from a medium brown to light brown in color.
The specific epithet, “royi” is a patronym named for Roy McDiarmid, herpetologist and biological coordinator for the survey of the flora and fauna of Cerro de la Neblina.
The type specimen was collected from a small, shallow brook about one to two meters wide and with occasional pools about one meter deep, with a substrate of sand, boulders, and bedrock. This small tributary originates on Cerro de la Neblina and feeds the Rio Baria, which drains most of the massif. The highwater marks and polished boulders along the stream bed indicate that in times of heavy rainfall, the brook becomes scoured by flash flooding. Paratypes were collected from similar small streams at high elevations.
Water quality data obtained by using colorimetric analyses of the brook at the type-locality are as follows; pH: 4, hardness: 0, oxygen: 9 ppm. The air temperature was 21°C and the water temperature was 17°C when the analyses were made.
The authors thank Robin A. Faitoute, Warren E. Steiner, and Phyllis M. Spangler for their help with collecting the adults and larvae of this new genus; Charles Brewer Carias, who coordinated the expedition to Cerro de la Neblina Park; Andrew Short for comments on earlier version of the manuscript and taking the scanning electron micrographs; and Taro Eldredge and Matthew Gimmel for proofreading the manuscript. This research was supported by Smithsonian Institution’s Scholarly Research Fund (to PJS) and US National Science Foundation grant #DEB-0816904 to Andrew Short.