Rivudiva oxum, 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 : 168-169

Rivudiva oxum sp. nov.

urn:lsid:zoobank.org:act:21BF614C-3B80-4307-82BE-F981DE45D244

Figs 8–11

Rivudiva trichobasis – Boldrini & Cruz 2014: 5. — Salles et al. 2020: 49 .

Diagnosis

NYMPH. The combination of the characters: 1) labrum distal margin straight ( Fig. 8A ); 2) labrum ventral surface with robust, distally bifid, eventually pectinated, setae on distal margin ( Fig. 8A ); 3) left mandible with incisors fused at middle ( Fig. 8B ); 4) maxillary palp segment II with inner distal protuberance, outer margin straight, with long distal lobe ( Fig. 8D–H ); 5) hypopharynx without distomedial projection ( Fig. 8I ); 6) glossae inner arc of setae following the inner margin at base, curved at apex, outer arc of setae sinuous ( Fig. 8J–K ); 7) labial palp segment III robust, conical and apically pointed ( Fig. 8J ); 8) dorsal margin of forefemur with one row of long setae from base to apex ( Fig. 9A ); 9) anterior surface of forefemur with blunt setae at middle ( Fig. 9A ); 10) patella-tibial suture absent; 11) distal margin of terga with triangular spines ( Fig. 10A ).

Etymology

ʻ Oxum ʼ is a female ʻ orixá ʼ (deity or goddess) from the Ijexá nation, adopted and worshipped in Afro- Brazilian religions. She is the fresh waters ʻ orixá ʼ (lakes, rivers and waterfalls), of wealth, love, prosperity and beauty. Name in apposition.

Material examined

Holotype BRAZIL • nymph on slide; Rondônia, Alto Alegre dos Parecis, line 24 southbound from RO-370 leaving Alto Alegre to the east, under the bridge; 12°12′57.8″ S, 061°47′18.4″ W; 8 Jul. 2016; P.V. Cruz leg.; INPA.

Paratypes BRAZIL • 3 nymphs; same collection data as for holotype; INPA • 3 nymphs; Rondônia, Machadinho do Oeste, RO-133 between Tabajara and 2 de novembro streams; 08°53′10.0″ S, 062°11′21.8″ W; 21 Aug. 2016; P.V. Cruz and N. Hamada leg.; INPA • 1 nymph; Rondônia, Alto Alegre dos Parecis, line 24 southbound from RO-370 leaving Alto Alegre to the east, at the curve at the foot of a hill; 12°14′22.8″ S, 061°47′26.9″ W; 9 Jul. 2016; P.V. Cruz and N. Hamada leg.; INPA • 5 nymphs; Rondônia, Alto Alegre dos Parecis, line 24 southbound from RO-370 leaving Alto Alegre to the east, at the curve at the foot of a hill; 12°14′23.2″ S, 061°47′26.7″ W; 8 Jul. 2016; P.V. Cruz and N. Hamada leg.; INPA • 2 nymphs; same locality as for preceding; 24 Jul. 2016; P.V. Cruz and N. Hamada leg.; INPA • 6 nymphs; Rondônia, Alto Alegre dos Parecis, line 24 southbound from RO-370 leaving Alto Alegre to the east, preserved area of PCH Santa Luzia, small stream; 12°20′37.4″ S, 061°45′26.3″ W; 9 Jul. 2016; P.V. Cruz leg.; INPA • 1 nymph; Rondônia, Nova União, Vale da Cachoeiras, Balneário , access by RO-470 or RO-473, below waterfall, from RO 470 on the left, 13 km; 10°55′18.0″ S, 062°22′34.6″ W; 1 Aug. 2016; P.V. Cruz and N. Hamada leg.; INPA • 4 nymphs; Amazonas, Humaitá, PARNA Campos Amazônicos , Veado stream ; 08°26′27.4″ S, 061°39′37.3″ W; 6 Jul. 2018; P.V. Cruz, N. Hamada and G. Desidério leg.; INPA .

Description

Nymph

LENGTH. Body, 3.3–3.5 mm.

HEAD.Antenna. Flagellum with minute spines on apex of each segment. Labrum ( Fig. 8A ). Rectangular, length about 0.6× maximum width; distal margin straight; one row of robust, distally bifid, 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 with many thin setae over surface. Left mandible ( Fig. 8B ). Incisors partially cleft in two sets (fused at middle); outer and inner sets of incisors respectively with 4 + 3 denticles, outer incisor with spine-like process; prostheca robust and pectinated; margin between prostheca and mola straight; tuft of spine-like setae at base of mola present; subtriangular process wide; denticles of mola constricted; mola with two large denticles, apex of mola with one simple seta; outer margin convex. Right mandible ( Fig. 8C ). Incisors fused at base; outer and inner sets of incisors respectively with 3 + 3 denticles, outer incisor with spine-like process; prostheca stout, bifurcated at apex, inner lobe longer; margin between prostheca and mola almost 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 rounded, second expanded and straight; outer margin convex. Maxilla ( Fig. 8D–H ). Maxillary palpi 1.7× length of galea-lacinia; segment II 0.9× length of segment I; segment II with inner distal protuberance, outer margin straight, with long distal lobe half of width of segment II apex; ventral canine enlarged, not laterally expanded; set of distal setae of the inner-ventral row rounded. Hypopharynx ( Fig. 8I ). Lingua longer than superlingua, sub-quadrangular, without distomedial projection, with medio-distal tuft of simple setae; superlingua with rounded outer margin; short, thin, simple setae scattered over distal margin of lingua and superlingua. Labium ( Fig. 8J–K ). Glossa slightly expanded at base, with parallel margins, distal margin slightly rounded, shorter than paraglossa; inner margin without row of setae; ventral surface covered by thin setae; dorsal surface with inner arc of robust pointed setae following the inner margin at base, curved at apex, outer arc of long robust setae following the inner margin at base, sinuous at apex; one small robust blunt seta on apex. Paraglossa curved inward; apex with one row of robust and long spine-like setae; outer margin without setae; dorsal surface with four longitudinal rows of setae, inner row longer than half of length of paraglossa, distally with long robust setae; ventral surface with one row of six setae near to inner margin, apex with one row of robust setae. Labial palp with segment I 0.8× length of segments II and III combined; inner distal protuberance of segment II rounded, covered with thin setae; segment III robust, conical, and apically pointed; outer margin with short thin setae, dorsal surface covered with short spine-like setae, ventral surface with two short spine-like setae, and covered by long thin setae.

THORAX. Foreleg ( Fig. 9A–C ). Femur length about 3.3× maximum width; dorsal margin with one row of long spine-like setae from base to apex; anterior surface with one medial row of blunt setae, one row of long spine-like setae near ventral margin reaching apex, one row of long spine-like setae near dorsal margin; posterior surface with one row of long spine-like setae near ventral margin from base to apex, and one medial row of long spine-like setae from base to apical third. Tibia. Dorsally bare; ventral margin with one row of long spine-like setae at apical half, patella-tibial suture absent. Tarsus. Ventral margin with one row of spine-like setae. Tarsal claws 0.5× length of tarsus, with two rows of small conical denticles not reaching apex. Hind leg ( Fig. 9D–E ). Femur dorsal 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, one row of spine-like setae near middle; posterior surface with one row of spine-like setae near ventral margin. Tibia. Dorsally bare; ventral margin with two small blunt setae base, patella-tibial suture present. Tarsus. Ventral margin with one row of small blunt setae. Tarsal claws 0.6× length of tarsus, with two rows of small conical denticles reaching apex.

ABDOMEN. Terga ( Fig. 11 ) with all segments yellowish or white (color lost in alcohol), terga I–VIII with two small medial dots, sometimes dots absent; terga III and VIII with one large dot on distal margin (eventually absent); tergum IX darker. Posterior margin of terga with triangular spines ( Fig. 10A ). Gills oblong, longer than next segment, with one medial trachea pigmented. Paraproct ( Fig. 10B ) with seven to nine marginal spines, posterolateral extension with spines. Cerci ( Fig. 10C ) with lateral spines on every segment. Paracercus ( Fig. 10D ) without spines.

Comments

The variation presented in Fig. 8E–F is related to the slide mount artifact. In Fig. 8E , the maxillary palp is in outer margin view, while in Fig. 8G–H it is in lateral view. The palps presented in Fig. 8G–H are true variations of the segment II and its distal lobe.

Figures

Fig. 8. Rivudiva oxum sp. nov.A–D, I–K. Holotype (INPA). E–H. Paratypes (INPA). A. Labrum (left v.v., right d.v.). B. Left mandible. C. Right mandible. D. Maxilla. E–H. Variation of maxillar palp segment II (E–F is related to slide mounting). I. Hypopharynx. J. Labium (left v.v., right d.v.). K. Shape of distal rows of setae of glossa. Not to scale.

Fig. 9. Rivudiva oxum sp. nov., holotype (INPA). A. Foreleg (femur on anterior surface). B. Details of fore claw.C. Posterior surface of forefemur.D. Hind leg (femur on anterior surface). E. Posterior surface of hind femur. Not to scale.

Fig. 10. Rivudiva oxum sp. nov., holotype (INPA). A. Margin of tergum IV. B. Paraproct. C. Cercus. D. Paracercus. Not to scale.

Fig. 11. Rivudiva oxum sp. nov., dorsal habitus of nymphs, variation of pigmentation pattern. A. Holotype on slide (INPA). B–I. Paratypes (INPA). Scale bar = 1.65 mm.