Rivudiva trichobasis Lugo-Ortiz & McCafferty, 1998

Cruz, Paulo Vilela, Boldrini, Rafael, De Lima, Cláudia R. T. & Hamada, Neusa, 2022, It is a mess! How many species are in Rivudiva trichobasis Lugo- Ortiz & McCafferty, 1998 (Ephemeroptera: Baetidae)?, European Journal of Taxonomy 789 (1), pp. 153-191 : 157-159

Rivudiva trichobasis Lugo-Ortiz & McCafferty, 1998

Figs 1–3

Rivudiva trichobasis Lugo-Ortiz & McCafferty, 1998: 64 (type material).

Rivudiva trichobasis – Cruz et al. 2018: 10, figs 23, 29. — Lugo-Ortiz & McCafferty 1998: 64 (with some doubt, partim). — Salles et al. 2020: 49 (with some doubt).

not Rivudiva trichobasis – Cruz et al. 2011: 60 . — Falcão et al. 2011: 539. — Boldrini et al. 2012: 93. — Boldrini & Cruz 2014: 5.

Diagnosis (adapted from Salles et al. 2020)

NYMPH. The combination of the characters: 1) labrum with medial emargination ( Fig. 1B ); 2) labrum ventral surface with simple robust row of setae on distal margin ( Fig. 1B ); 3) left mandible with incisors fused at middle length ( Fig. 1C ); 4) maxillary palp segment II with robust apical lobe ( Fig. 1E ); 5) ventral canine expanded, laterally folded over canines; 6) hypopharynx with small distomedial projection ( Fig. 1F ); 7) outer arc of setae on glossa with apical half not sinuous, far from distal margin ( Fig. 1G–H ); 8) labial palp segment III narrow and conical ( Fig. 1G ); 9) dorsal margin of forefemur with one row of long spine-like setae from base to apex ( Fig. 2A ); 10) forefemur on anterior surface with medial row of elongate blunt setae ( Fig. 2A ); 11) patella-tibial suture absent; 12) distal margin of terga with wide marginal spines ( Fig. 3A ).

Material examined

Paratype BRAZIL • 1 nymph; Rio Grande do Sul State, Arroio dos Vargas; 30°50′ S, 53°10′ W; 120 m a.s.l.; Nov. 1964; F. Plaumann leg; IBN slide #270 .

Redescription

Nymph

HEAD. Antenna ( Fig. 1A ). Flagellum with minute spines on apex of each segment. Labrum ( Fig. 1B ). Rectangular, length about 0.7× maximum width; distal margin with medial emargination, one row of robust, eventually pectinated, setae from lateral to middle; one row of thin bifid setae on distal margin not reaching distolateral margin; dorsal surface, near distal margin, with many thin setae over surface. Left mandible ( Fig. 1C ). Incisors partially cleft in two sets (fused at middle length); outer and inner set of incisors respectively with 4 + 3 denticles, outer incisor without spine-like process; prostheca robust and apically pectinate; margin between prostheca and mola straight; tuft of spine-like setae at base of mola absent; subtriangular process wide; denticles of mola not constricted; mola with one large denticle; outer margin convex. Right mandible ( Fig. 1D ). Incisors fused at base; outer and inner set of incisors respectively with 3 + 3 denticles, outer incisor with one spine-like process; prostheca stout, bifurcated at middle, inner lobe longer 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 one simple setae; first process of mola triangular, second expanded and straight; outer margin convex. Maxilla ( Fig. 1E ). Maxillary palp 1.6× length of galea-lacinia; segment II 1.0× length of segment I, apex with robust apical lobe; ventral canine expanded, laterally folded over canines; set of distal setae of inner-ventral row clavate, base of maxilla broken. Hypopharynx ( Fig. 1F ). Lingua longer than superlingua, sub-quadrangular with a small distomedial projection covered by tuft of simple setae; superlingua with rounded outer margin; short, thin, simple setae scattered over distal margin of lingua and superlingua. Labium ( Fig. 1G–H ). Glossa slightly broad at base, with parallel margins, distal margin slightly rounded with small concavity and shorter than paraglossa; inner margin with two short spine-like setae on half; ventral surface covered by thin setae; dorsal surface with inner arc close to inner margin, outer arc basal half of row close to outer margin, apical half of row not sinuous, far from distal margin; one long robust blunt seta on apex. Paraglossa curved inward; apex with two rows of robust and long spine-like setae; outer margin with two long setae; dorsal surface with three longitudinal rows of setae, first row near inner margin longer than half of length, with long robust setae; second with half of length of the inner row, with long robust setae; and third near to outer-distal margin, with long setae, ventral surface with one row of four setae near to ventral margin. Labial palp with segment I 0.8× length of segments II and III combined; inner distal protuberance of segment II rounded, covered with thin, long simple setae; segment III narrow and conical (folded in slide studied), covered by thin simple setae, dorsal surface with robust spine-like setae near inner margin.

THORAX. Foreleg ( Fig. 2A–C ). Femur length about 3.2× maximum width; anterior surface with one medial row of elongate and blunt setae, one row of long spine-like setae near ventral margin not reaching apex; posterior surface with one row of long spine-like setae near dorsal margin not reaching apex, and one row of long spine-like setae near ventral margin reaching apex. Tibia. Dorsally bare; ventral margin with one row of long spine-like setae increasing in length to apex; patella-tibial suture absent. Tarsus. Ventral margin with one row of spine-like setae. Tarsal claws ( Fig. 2B ) 0.3× length of tarsus, with two rows of conical denticles not reaching apex. Hind leg ( Fig. 2D–E ). Femur anterior surface with one row of spine-like setae near dorsal margin on distal half, one row of long spine-like setae near ventral margin; posterior surface with one row of long spine-like setae near dorsal margin not reaching apex, one row of spine-like setae near ventral margin reaching apex. Tibia. Dorsally bare; ventral margin with one row of small blunt setae; patella-tibial suture present. Tarsus. Ventral margin with one row of small blunt setae. Tarsal claws ( Fig. 2D ) 0.5× length of tarsus, with two rows of small conical denticles reaching apex.

ABDOMEN. Terga III and VI with large medium brown mark. Posterior margin of terga with small triangular spines ( Fig. 3A–B ). Gills missing. Paraproct ( Fig. 3C ) with nine to twelve wide marginal spines, posterolateral extension with spines. Cerci ( Fig. 3D ) with lateral spines on every segment. Paracercus ( Fig. 3E ) without spines.

Comments

Based on the study of type material, records from Brazil, Roraima ( Falcão et al. 2011), Rondônia ( Boldrini & Cruz 2012), Amazonas ( Cruz et al. 2011) and Maranhão (R. sp. X) ( Boldrini et al. 2012), are not R. trichobasis . The specimens from Espírito Santo ( Brazil) ( Salles et al. 2020) and Paraguay (Paraguarí) could not be evaluated.

Distribution

Brazil (Rio Grande do Sul). Paraguay (Paraguarí) is treated here as putative; records from Espírito Santo ( Brazil) ( Salles et al. 2020) are treated here as putative and must be evaluated.

Figures

Fig. 1. Rivudiva trichobasis Lugo-Ortiz & McCafferty, 1998, paratype (IBN slide #270). A. Scape and pedicel. B. Labrum (left v.v., right d.v.). C. Left mandible. D. Right mandible. E. Apex of maxilla (base was deformed in slide). F. Hypopharynx. G. Labium (left v.v., right d.v.). H. Shape of distal rows of setae of glossa. Not to scale.

Fig. 2. Rivudiva trichobasis Lugo-Ortiz & McCafferty, 1998, paratype (IBN slide #270). A. Foreleg (femur on anterior surface). B. Detail of fore claw. C. Posterior surface of forefemur. D. Hind leg. E. Posterior surface of hind femur. Not to scale.

Fig. 3. Rivudiva trichobasis Lugo-Ortiz & McCafferty, 1998, paratype (IBN slide #270). A. Margin of tergum IV. B. Surface of sternum IV. C. Paraproct. D. Cercus. E. Paracercus. Not to scale.