Apobaetis jacobusi, Cruz & Boldrini & Hamada, 2020

Cruz, Paulo Vilela, Boldrini, Rafael & Hamada, Neusa, 2020, Redescription of Apobaetis lakota McCafferty, 2000 (Ephemeroptera: Baetidae) and description of two new species from Brazil, Zootaxa 4885 (2), pp. 249-258 : 254-257

Apobaetis jacobusi sp. nov.

( Figs 3 A–3J, 4C–4E)

Diagnosis. Larva. 1) labrum rectangular, broader than long, medially with two protuberances ( Fig. 3A ); distal margin, between medial lobe and lateral denticle, with thin setae; 2) maxillary palp long, more than 2.0× the length of galea-lacinia; segment I robust, longer than galea-lacinia ( Fig. 3D ); 3) lingua subquadrate with one small medial lobe ( Fig. 3E ); 4) glossa distally pointed ( Fig. 3F ); 5) inner projection of labial palp of segment II rounded, segment III of labial palp triangular ( Fig. 3F ); 6) tarsal claw I with the same length as tarsus, without row of denticles ( Fig. 3G ); 7) posterior margin of tergum IV with triangular spines (longer than wide) ( Fig. 3H ).

Description. Larva. Head: Antenna with minute spines and thin, simple setae on apex of each segment. Frons with two small parallel keels, slightly concave (almost flat) between keels. Labrum ( Fig. 3A ): rectangular, broader than long; distal margin without shallow medial emargination; medially with two protuberances, area between them with thin setae; medial area of distal margin with one row of long thin setae on dorsal surface; ventral surface with one row of robust setae at distal margin. Left mandible ( Fig. 3B ): outer and inner sets of incisors with 4 and 3 denticles, respectively; prostheca robust, inner margin frayed at distal half; margin between prostheca and mola concave, with frayed lobe close to subtriangular process; tuft of robust setae at base of mola present; subtriangular process wide; denticles of mola not constricted; lateral margin convex. Right mandible ( Fig. 3C ): outer and inner sets of incisors with 3 and 2 denticles, respectively; prostheca slender; margin between prostheca and mola concave; tuft of robust setae at base of mola present; denticles of mola not constricted; lateral margin convex. Maxilla ( Fig. 3D ): maxillary palp long, more than 2.0× the length of galea-lacinia; segment I robust, longer than galea-lacinia; segment II robust, without distal constriction; maxillary palp with thin, simple setae scattered over the surface. Hypopharynx ( Fig. 3E ): lingua subquadrate and longer than superlingua, with one small medial lobe and without distal tuft of setae; superlingua not expanded, with short, thin, simple setae scattered over distal margin. Labium ( Fig. 3F ): glossa narrowing slightly distally on inner margin and with apex pointed, longer than paraglossa; dorsal surface with one arc of robust setae on distal third, from inner to outer margin; ventral surface with distal row of robust setae, covered with thin setae. Paraglossa curved inward; dorsal surface with one longitudinal row of four robust setae near inner margin; apex with one robust seta; outer margin with one row of eight robust setae; ventral surface with one longitudinal row of four robust setae in the middle. Labial palp with segment I 0.8× the length of segments II and III combined; inner projection of labial palp of segment II rounded, outer margin and projection covered with thin, long, simple setae; segment III triangular, covered with thin, long, simple setae on outer margin, dorsal surface with one row of six robust setae, outer margin almost straight. Thorax. Foreleg ( Fig. 3G ). Femur: with one row of eight short blunt setae on dorsal margin; apex with two short blunt setae; ventral margin with one row of six short robust setae. Tibia: ventrally with one row of 12 short robust setae. Patella-tibial suture from dorsal to ventral margin. Tarsus: ventrally with one row of 12 short robust setae. Tarsal claws the same length as tarsus, row of denticles absent. Claws II and III slightly longer than tarsus. Abdomen. Tergum II darker, tergum V with one dark mark, terga V–IX with one reddish mark on distolateral margin ( Figs 4 C–4E). Tergal surface creased, with micropores (not illustrated); posterior margin with triangular spines (longer than wide) ( Fig. 3H ). Gill VI, rounded ( Fig. 3I ), outer margin slightly expanded (all other gills broken and lost). Paraproct ( Fig. 3J ) with four marginal spines, posterolateral extension with few spines. Cerci and paracercus with lateral spines on all segments.

Comments. The new species was found in the riverbed (sand bottom), one meter deep in the dry season. The river, in the sector where the new species was collected, has approximately five meters width; it is surrounded by pasture, almost without riparian vegetation.

Etymology. We dedicate this species to Luke M. Jacobus for his contribution to the knowledge of mayflies and who gave great support to the first author (P.V.C.) at the Purdue Entomological Research Collection, U.S.A.

Material examined. Holotype, one larva on slide, Brazil, Rondônia, Nova Londrina district, Ji-Paraná, Rio Urupá , Balneário no Nelim , access to the farm by secondary road (” linha ” in Portuguese) No. 6, S11°02’11.4” W062°08’41.5”, 25.viii.2016, Cruz P. V. & Hamada N. cols., INPA . Paratype, one larva in 80% ethanol, same data as holotype, INPA .

Figures

FIGURE 3A–J. Apobaetis jacobusi sp. nov. A. labrum (left d.v., right v.v.); B. left mandible; C. right mandible; D. maxilla; E. hypopharynx; F. labium (left d.v., right v.v.); G. foreleg; H. posterior margin of tergum IV; I. gill VI; J. paraproct.

FIGURE 4A–D. Larval habitus. A. Apobaetis biancae sp. nov., dorsal view; B. Apobaetis biancae sp. nov., lateral view; C. Apobaetis jacobusi sp. nov., dorsal view; D. Apobaetis jacobusi sp. nov., lateral view; E. Apobaetis jacobusi sp. nov., ventral view.