Rivudiva naia, Cruz & Boldrini & De Lima & Hamada, 2022

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 : 179-184

Rivudiva naia sp. nov.

urn:lsid:zoobank.org:act:FC398BC7-7504-4F40-AF67-9479BABF0926

Figs 16–18

Diagnosis

NYMPH. The combination of the characters: 1) labrum distal margin straight ( Fig. 16A); 2) labrum ventral surface with simple or pectinated robust setae on distal margin ( Fig. 16A); 3) left mandible with incisors fused at basal third ( Fig. 16B); 4) maxillary palp segment II with large apical lobe ( Fig. 16D); 5) superlingua with truncate outer margin ( Fig. 16F); 6) outer arc of robust setae of glossa close to margin, slightly removed from distal margin ( Fig. 16G); 7) labial palp segment III conical, apex broad pointed ( Fig. 16G); 8) dorsal and ventral margin of forefemur with one row of long spine-setae from base to apex ( Fig. 17A); 9) forefemur on anterior surface with short blunt setae at middle ( Fig. 17A); 10) patella-tibial suture present; 11) distal margin of terga with wide spines (18A).

Etymology

ʻ Naia ʼ in Amazonian folklore is the name of the native woman that, after being drowned by the enchantment of the god Moon, was transformed into a water star – Victoria Regia (Victoria amazonica (Poepp.) J.C.Sowerby). For this reason, the fragrant whitish flowers of this plant only open at night. Name in apposition.

Material examined

Holotype

BRAZIL • nymph on slide; Roraima, Mucajaí, Apiaú, waterfall Esmeralda ; 02°29′42.76″ N, 61°23′41.61″ W; 14 Feb. 2021; R. Boldrini leg.; sand; UFRR.

Paratypes

BRAZIL • 1 nymph; same collection data as for holotype; UFRR • 1 nymph; same collection data as for holotype; UFV • 1 nymph; same collection data as for holotype; INPA .

Description

Nymph

LENGTH. Body, 4.1–4.9 mm.

HEAD.Antenna. Flagellum with minute spines on apex of each segment. Labrum ( Fig. 16A). Rectangular, length about 0.6× maximum width; distal margin straight, one row of robust, eventually pectinated, setae from lateral to middle of distal margin; 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. 16B). Incisors partially cleft in two sets (fused at basal third); outer and inner set of incisors respectively with 4 + 3 denticles; prostheca robust; 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 two large denticles, inner larger than outer; outer margin convex. Right mandible ( Fig. 16C). Incisors fused at base; outer and inner set of incisors respectively with 3 + 2 denticles and outer incisor with spine-like process; prostheca stout, bifurcated at base, inner lobe longer than outer; 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 seta; first process of mola triangular, second expanded and straight; outer margin convex. Maxilla ( Figs 16D). Maxillary palp 1.8× length of galea-lacinia; segment II 1.2× length of segment I; segment II inner margin with large apical lobe; ventral canine enlarged, not laterally expanded; set of distal setae of the inner-ventral row pointed. Hypopharynx ( Fig. 16E). Lingua longer than superlingua, sub-quadrangular with a small distomedial projection covered by tuft of simple setae; superlingua with truncate outer margin; short, thin, simple setae scattered over distal margin of lingua and superlingua. Labium ( Fig. 16F–G). Glossa slightly expanded at base, distally rounded, shorter than paraglossa; ventral surface covered by thin setae; dorsal surface with inner arc with setae following inner-distal margin, outer arc at base following outer margin, slightly far from distal margin. Paraglossa curved inward; apex with one row of robust and long spine-like setae; outer margin with four long thin setae; dorsal surface with four longitudinal rows of setae, first near inner margin longer than two third of length, distally with long robust setae and basally with long thinner setae; second with third of length of inner row, with robust long setae; and third with same length as second, distal setae long and robust, basal setae long and thin; ventral surface with one row of five 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 and projected to apex, covered with thin setae; segment III conical, apex broad pointed; outer margin with short thin setae, dorsal surface with one row of short spine-like setae near inner margin, ventral surface with one row of thin setae.

THORAX. One mark on mesothorax. Foreleg ( Fig. 17A–C). Femur length about 2.9× maximum width; dorsal and ventral margin with one row of long spine-like setae; anterior surface with one medial row of short setae, one row of blunt setae near dorsal margin not reaching apex; posterior surface with one row of long spine-like setae near ventral margin reaching apex, and one medial row of long spine-like setae. Tibia. Dorsally bare; ventral margin with one row of long spine-like setae; patella-tibial suture present. Tarsus. Ventral margin with one row of spine-like setae. Tarsal claws 0.4× length of tarsus, with two rows of rounded denticles at basal half. Hind leg ( Fig. 17D–E). Femur dorsal and ventral margin with one row of long spine-like setae; anterior surface with one row of spine-like setae near dorsal margin, one row of long spine-like setae near ventral margin; posterior surface with one row of spine-like setae near ventral margin at basal half. Tibia. Dorsally bare; ventral margin with one row of small spine-like setae; patella-tibial suture present. Tarsus. Ventral margin with one row of small spine-like setae. Tarsal claws 0.5× length of tarsus, with two rows of rounded and small denticles reaching apex.

ABDOMEN. Terga ( Fig. 18E) with all segments white (color lost in alcohol), tergum IV with one medialred mark; tergum V with one large medial red mark; tergum IX with one red mark near lateral margin. Posterior margin of terga with small triangular blunt spines ( Fig. 18A). Gills oblong, longer than next segment, with one medial trachea red pigmented. Paraproct ( Fig. 18B) with two marginal spines, posterolateral extension with spines. Cerci ( Fig. 18C) with lateral spines on every segment. Paracercus ( Fig. 18D) without spines.