Brasilocaenis atawallpa Lima, Molineri, Vieira, Pinheiro & Salles, 2019

Nascimento, Stênio R. S., Cruz, Paulo V., Silva, Myllena S. L., Firmino, Viviane C., Brasil, Leandro S., Juen, Leandro & Lima, Lucas R. C., 2021, Description of nymph of Brasilocaenis atawallpa Lima, Molineri, Vieira, Pinheiro & Salles, 2019 (Ephemeroptera: Caenidae) and notes on its taxonomic status, Zootaxa 5027 (1), pp. 136-144 : 137-141

publication ID	https://doi.org/ 10.11646/zootaxa.5027.1.8
publication LSID	lsid:zoobank.org:pub:98D8713D-CD6A-4294-8FC7-BC78AA6F19F7
persistent identifier	https://treatment.plazi.org/id/7F4D87A9-FF9B-FFA8-FF70-FA33FC4ADEB3
treatment provided by	Plazi
scientific name	Brasilocaenis atawallpa Lima, Molineri, Vieira, Pinheiro & Salles, 2019
status

Treatment

Figs 2A–F View FIGURE 2 , 3A–J View FIGURE 3 , 4A–B View FIGURE 4

Diagnosis. This species can be characterized by the following combination of characters in the male imago: 1) body length 2.1–2.4 mm; 2) base of antennal flagellum slightly dilated basally; 3) forceps apically pointed, sharpening abruptly, strongly curved downward at apex, fused in the lateral margins of styliger plate, except apical part; 4) styliger plate completely covering the penis, as wide as long with a deep medial emargination forming two short lateral lobes (some specimens have reduced lobes); 5) penis with dorsolaterally protruding lobes and a sculptured median part. The nymph presents the following combination of characters: 1) anterolateral margins of pronotum rounded and projected laterally ( Fig. 2D View FIGURE 2 ); 2) forecoxa without projection, middle coxa with well-developed semicircular projection, hind coxa with finger-like projection ( Figs 3H–J View FIGURE 3 ); 3) fore and middle tarsal claws without denticles, hind tarsal claw with ca. 32 small denticles ( Fig. 3G View FIGURE 3 ); 4) hind margin of sternum IX straight; 5) posterolateral projections on abdominal segments V–VIII long and pointed; 6) dorsal surface of operculate gills smooth with long and simple setae ( Fig. 2E View FIGURE 2 ).

Description. Mature male nymph. Length: Body, 3.0– 3.4 mm, cercus, 2.9–3.8 mm. Ratios: Mouthparts. Width of maxillary palp segment I 1.7x width of segment II; length of maxillary palp segment I 1.7x length of segment II; length of maxillary palp segment I 0.9x length of segment III; length of labrum 0.5x its maximum width. Foreleg. Length of forefemur 2.9x its maximum width.

Coloration and Morphology. Head: Light brown; occiput and mouthparts paler, grayish markings on posterior margin of occiput; also shaded gray behind eyes. Antenna: Flagellum hyaline ( Figs 2A–D View FIGURE 2 ). Hind margin of head without setae. Mouthparts: Labrum with lateral margins rounded, with long subapical setae over the dorsal surface ( Fig. 3A View FIGURE 3 ). Mandibles with outer margin with a dorso-lateral row of long setae ( Figs 3D, E View FIGURE 3 ); anterior margin of lingua medially excavated ( Fig. 3B View FIGURE 3 ). Thorax: Nota brownish with black sutures. Pronotum with anterior margin yellowish, translucent anterolateral corners, lateral zones shaded with black, with blackish paramedian dots, and blackish median elongated marks ( Figs 2A, B View FIGURE 2 ). Mesonotum with blackish macula anterior to wingbud bases, and with a pair of medial brownish lines ( Fig. 2A View FIGURE 2 ). Thoracic sterna paler than terga ( Fig. 2C View FIGURE 2 ). Pronotum with anterolateral margins rounded and projected laterally ( Fig. 2D View FIGURE 2 ). Legs yellowish, femora with blackish marks on subapical zones and basally on median and hind femora; tibiae blackish on subapical zones ( Fig. 2B View FIGURE 2 ). Fore coxa without projection, middle coxa with projection well-developed and semicircular, hind coxa with finger-like projection ( Figs 3H–J View FIGURE 3 ). Dorsal margin of fore femora with long robust setae, varying in size, mostly on apical half ( Fig. 3H View FIGURE 3 ); median and hind femora with long robust setae on dorsal margin ( Figs 3I, J View FIGURE 3 ). All tarsi with one row of setae on inner margin ( Figs 3H–J View FIGURE 3 ). Anterior and median tibiae with robust setae on inner margins, varying in size; hind tibiae with long and robust setae on inner and outer margins ( Figs 3 H–J View FIGURE 3 ). Fore and middle tarsal claws without denticles, hind tarsal claw with ca. 32 small denticles ( Fig. 3G View FIGURE 3 ). Abdomen: Terga brownish; segments I–VI with a grayish band on medial area, paler laterally; segments VII–X paler medially and darker laterally ( Figs 2A–B View FIGURE 2 ). Operculate gills translucent brownish, almost completely shaded with black and apically with three blackish spots ( Figs 2A, E View FIGURE 2 ). Abdominal sterna light brown, with only small grayish sublateral marks. Tergum II with small median projection on posterior margin, wide at base and slightly curved on apex. Marginal row of elongated and apically frayed microtrichia along ventral surface of operculate gills ( Fig. 2E View FIGURE 2 ); dorsal surface smooth with long and simple setae, and medial Y-ridge complete and well developed ( Figs 2A, E View FIGURE 2 ). Posterolateral projections on abdominal segments V–VIII long (reaching half of next tergum) and pointed. Sternum IX with hind margin straight, laterally with long simple setae ( Figs 4B View FIGURE 4 ). Caudal filaments yellowish ( Fig. 2C View FIGURE 2 ).

Life cycle association. Male genitalia extracted from mature nymphs and compared with the imagos ( Fig. 4B View FIGURE 4 ).

Distribution. Colombia and Brazil (new country record).

Ecology. Brasilocaenis atawallpa nymphs were found in shallow portions with slow to moderate current in lotic environments, occurring predominantly in areas with riparian vegetation composed of bamboo forest. The drained soil is of the clayish type with deposition and accumulation of organic matter (leaf packs, trunks, live roots), and water with high dissolved oxygen concentrations. The bamboo occurrence in the riparian vegetation may be favored by both the dry regional climate and the present human disturbance in the forests in Acre State ( Ferreira 2014, Ferreira et al. 2020). In addition, the bamboo population spreads vegetatively in relatively open sites, like clearings at the edges of roads, pasture and agricultural areas ( Dalagnol et al. 2018).

Material examined. Lectotype: One ♂ imago, Colombia, Departamento Amazonas, Parque Nacional Ama- cayacu, Quebrada Mata-mata , 03°48’28”S, 70°15’21”W, 02.ii.1999, Zuñiga, M.C., Molineri, C., Domínguez, E. cols, light trap, MUSENUV GoogleMaps . Paralectotypes: Four ♂ imagos, same data as holotype, (slides IBN659 CM and IBN660 CM) GoogleMaps ; 168 ♂ imagos, same data as preceding except, 05.ii.1999 GoogleMaps ; 50 ♂ imagoes, CZNC . 70 ♂ imagos, MUSENUV and 48 ♂ imagoes IBN ; 3 ♂ imagos, Depto. Amazonas, Puerto Nariño, 03°43’53”S, 70°21’59”W, 04.ii.1999, Zuñiga, M.C., Molineri, C., Domínguez, E. cols, light trap, IBN GoogleMaps ; 98 ♂ imagos, (slides IBN616 CM, IBN617 CM and IBN618 CM), Depto. Amazonas, Leticia, Caño Km 11 ruta a Tarapaca , 28.i.1999, Zuñiga, M.C., Molineri, C., Domínguez, E. cols, light trap, IBN .

Additional material: 2nymphs, Brazil, Acre State, Assis Brasil municipality, Reserva Extrativista Chico Mendes, Riacho CM05 ; 10°36’33.49”S, 69°35’47.55”W, 240 m a.s.l., 06.viii.2019, R. C. Bastos col GoogleMaps , aquatic net, INPA ; 2 nymphs, same data as preceding except, Riacho CM07 , 10°8’56.89”S, 69°38’57.2”W, 240 m a.s.l., 08.viii.2019, UFVB-EP00201 GoogleMaps ; 2 nymphs, same data as preceding except, Riacho CM06 GoogleMaps , 10°40’07.62”S, 69°35’46.32”W, 300 m a.s.l., UFVB-EP00202 GoogleMaps ; 2 nymphs (legs and genitalia mounted on slide), Acre State, Sena Madureira municipality, Reserva Extrativista Cazumbá-Iracema, Riacho CZ10, 9°8’42.3”S, 69°00”44.97”W, 170 m a.s.l., 28.viii.2019, Bastos , R . C. col, aquatic net, UFVB-EP00203 .

Discussion. The description of Brasilocaenis atawallpa ( Lima et al. 2019) does not contain a designation of type specimens or locality, it just states that the type series of this species was studied in order to perform the cladistic analysis. In the manuscript, the table of material examined (table 1 in Lima et al. 2019), indicates the name and location of institutions where the specimens are deposited, in accordance with item 16.4.2. of the Code. Three consulted curators confirmed that the specimens are in their institutions. In a supplementary document the authors presented a list of material examined, but this document does not satisfy several criteria established in Article 8 of International Code on Zoological Nomenclature. However, there is mention to type series in the original publication, and the specimens are deposited in collections with its names and locations clearly shown in the labels.Additionally, the description satisfies the criteria established in Article 8. In this context, we herein designated the lectotype and paralectotypes of Brasilocaenis atawallpa as presented in the ‘Results’ section, under ‘Material examined’.

The nymphal stage of B. atawallpa shows characteristics clearly associated with Caenis , rather than Brasilocaenis , such as absence of pointed microspines on the dorsal surface of opercular gill II and coxal projections semicircular. Both characteristics are also observed in Brasilocaenis elidioi ( Lima, Molineri, Pinheiro & Salles, 2016) , but B. atawallpa distinguishes by the presence of long and sharp posterolateral projections on abdominal segments V–VIII (short in B. elidioi ), tarsal claw III with denticles (absent in B. elidioi ) and hind margin of the ninth sternite almost straight (rounded in B. elidioi ).

The divergence from the generic diagnosis provided by Lima et al. (2019) was expected, since only four species have nymphs described. Regardless of morphological divergences from ‘typical’ Brasilocaenis nymph, the male genitalia extracted from mature nymphs present the forceps curved inward at apex, fused with lateral margins of the styliger plate (except apical part), which is one of the synapomorphies of Brasilocaenis ( Lima et al. 2019) . The male genitalia extracted from mature nymph can be associated with B. atawallpa by forceps apically pointed, sharpening abruptly, strongly curved downward at apex; styliger plate covering completely the penis, as wide as long with a deep medial emargination forming two short lateral lobes ( Figs 4A–B View FIGURE 4 ).