Rivudiva inma Salles & Nieto & Cruz 2020, sp. nov.
Creators: name: Salles, F. F.
name: Nieto, C.
name: Cruz, P. V.
Publisher: name: Zenodo
Year: 2020
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Ephemeroptera
Baetidae
Rivudiva
Rivudiva inma

description: Rivudiva inma Salles & Nieto, sp. nov.
Rivudiva minantenna (misidentification): Salles & Nascimento (2009: 233); Salles et al. (2010: 303).
Material examined. Holotype (male adult with corresponding exuviae): BRAZIL, Espírito Santo state, Santa Teresa, Capitel de Santo Antônio, S 19°52’33” W 40°31’50”, 720 m. a.s.l., 19.ii.2009, FF Salles leg. (UFVB, #EP000150). Paratypes: same data as holotype, 2 nymphs (IBN); same data as holotype, except for 20.ii.2009, 14 nymphs (UFVB, 1 used for SEM images, #EP000151); same data as holotype, except 26.x.2008, 4 nymphs (UFVB, #EP000152).
Diagnosis
Nymph. 1) antenna without spine-like setae on scape and pedicel; 2) distal margin of labrum with deep, wide, medial emargination (Figs 1, 22); 3) dorsal surface of labrum with regular row of setae, plus few additional setae (Figs 1, 22); 4) tuft on apex of lingua formed by long simple setae (Fig. 4); 5) maxillary palp segment II apically rounded and with a nipple-like projection (Figs 5, 24); 6) glossa with base ventrally expanded, apex obliquely truncate and with dorsal thick setae distomedially (Fig. 6); 7) hind wing pads present; 8) trochanter with robust, short and apically pointed setae (Fig. 7); 9) outer dorsal row, medial dorsal row and inner dorsal row of femora with robust blunt setae, those of outer row at most 1/3 maximum width of femur (Figs 7, 30–31); 10) abdominal sterna without robust apically pointed setae; 11) paraproct with around 15 marginal spines (Fig. 10).
Imago. 1) dorsal portion of turbinate eyes with inner margins parallel (Fig. 1 of Salles & Nascimento 2009); 2) length of forewing about 2.7× width; 3) hind wings present (fig. 5 of Salles & Nascimento 2009); 4) forceps segment III oblong, 2× as long as wide (fig. 6 of Salles & Nascimento 2009); 6) posterior margin of subgenital plate with a medial pointed projection (fig. 6 of Salles & Nascimento 2009).
Description
Nymph. Lengths: body, 5.2 mm; antennae, 1.8 mm.
Head. Coloration: pale yellow. Antenna pale yellow. Compound eyes pale yellow. Antenna. Scape and pedicel without spine-like setae. Labrum (Figs 1, 22). Rectangular, broader than long; length about 0.6x maximum width; distal margin with wide medial emargination; anterolateral and distal margins with bifid and pectinate setae; dorsal surface near distal margin with somewhat regular row of several simple setae. Left mandible (Fig. 2). Incisors cleft in two sets; outer and inner set of incisors respectively with 4 + 2 denticles; prostheca robust; margin between prostheca and mola straight; tuft of spine-like setae at base of mola present; subtriangular process wide; denticles of mola constricted; lateral margins convex. Right mandible (Fig. 3). Incisors deeply cleft in two sets; outer and inner set of incisors respectively with 3 + 3 denticles; prostheca bifurcated at middle and pectinate; margin between prostheca and mola straight; tuft of spine-like setae at base of mola present; denticles of mola not constricted; apex of mola with two simple setae; lateral margins convex. Hypopharynx (Fig. 4). Lingua subequal to superlingua, subquadrangular with a distomedial pointed projection covered by tuft of long simple setae; superlingua with angulate outer margin; short, thin, simple setae scattered over distal margin of lingua and superlingua. Maxilla (Figs 5, 24– 25). Maxillary palp 1.5× longer than galea-lacinia; segment II and III combined 0.8× the length of segment I, apex with inner nipple-like projection; maxillary palp with fine and simple setae scattered over surface. Labium (Fig. 6). Glossa oblong, basally expanded, narrowing apically and subequal to paraglossa; apex with eight short spine-like setae; outer margin bare; inner margin with row of thick setae on apical 2/3; ventral surface covered by thin long setae. Paraglossa curved inward, but with distinct apical margin; apex with three rows of robust long spine-like setae; outer margin with long thin setae on distal 1/2. Labial palp with segment I subequal in length to segments II and III combined; segment II with rounded medial protuberance, outer margin and distomedial protuberance covered with thin, long and simple setae; segment III conical, length 0.7× width, covered by thin simple setae on outer margin, dorsal surface with robust spine-like setae near outer margin.
Thorax. Pale yellow. Hind wing pads present. Legs pale yellow. Foreleg (Figs 7, 30–31). Ratio of foreleg 1.2:(1):0.9:0.3. Fore femur. Length about 2.7× maximum width; outer and inner margins with short to elongate clavate setae, anterior and posterior surface covered with longitudinal row of clavate robust setae; length of setae on outer margin at most 1/3 maximum width of femur. Tibia. Dorsally bare; inner margin with a row of spine-like setae increasing in length toward apex. Tarsus. Inner margin with a row of spine-like setae. Tarsal claws as in Figs 8 and 34. Mid and hind leg. Femora narrower than fore femora; setae on anterior surface of femora longer than in fore femur; setae on posterior surface longer and pointed. Tibiae and tarsi with one row of short spine-like setae.
Abdomen. Pale yellow, terga II–III and VI yellowish brown, anterior margins of segments II-VI brownish (Figs 38–39). Tergal surface covered by pores and short spine-like setae; posterior margin with contiguous spination (Fig. 9). Sterna pale yellow, bare. Gills whitish. Paraproct (Fig. 10) with around 15 marginal spines. Cercus and terminal filament without large lateral spines.
Imago. Adequately characterized by Salles & Nascimento (2009), although incorrectly associated to R. minantenna.
Etymology. After the Instituto Nacional da Mata Atlântica (INMA), the Brazilian National Institute of the Atlantic Forest. INMA is located in the city of Santa Teresa, locality of the new species, and one of the institute’s most important mission is the conservation of the Atlantic Forest and, therefore, of the new species.
Comments. Specimens of this species have been incorrectly assigned to R. minantenna by Salles & Nascimento (2009) due to several characteristics shared by them (see discussion for more details). The adults of the new species differ from the adults of R. covaloae, the other species with hind wings, by the shape of the distal margin of the subgenital plate. In R. covaloae the medial spine lies in a concavity of this margin (see fig. 2 of Traver 1971), while in the new species the distal margin is convex (see fig. 6 of Salles & Nascimento 2009).
Distribution. Southeastern Brazil, Espírito Santo (Fig. 41).
Biology. Nymphs of the new species were found inhabiting the sandy substrates of few streams in Augusto Ruschi Biological Reserve, Espírito Santo, or in adjacent areas. They are difficult to collect due to an apparently low abundance and/or to an apparently patchy distribution in the extensive sandy areas of these streams. Besides, the color pattern of the nymphs generates a remarkable camouflage with its habitat (see fig. 8 of Salles & Nascimento 2009).
description: Published as part of Salles, F. F., Nieto, C. & Cruz, P. V., 2020, New species of Rivudiva Lugo-Ortiz & McCafferty (Ephemeroptera: Baetidae) with comments on R. minantenna Lugo-Ortiz & McCafferty and R. trichobasis Lugo-Ortiz & McCafferty, pp. 37-52 in Zootaxa 4786 (1) on pages 39-42, DOI: 10.11646/zootaxa.4786.1.3, http://zenodo.org/record/3990784