Apobaetis signifer Lugo-Ortiz & McCafferty 1997

Cruz, Paulo Vilela, 2020, Redescription of three species of Apobaetis Day, 1955 (Ephemeroptera: Baetidae), Zootaxa 4808 (2), pp. 317-330 : 325

Apobaetis signifer Lugo-Ortiz & McCafferty 1997

Diagnosis. Larva. 1) labrum rectangular, distal margin without shallow medial emargination, dorsal surface with three to four short and blunt setae medially near distal margin ( Fig. 6A ); 2) lingua subquadrangular, with one medial protuberance ( Fig. 6D ); 3) maxillary palp long, 1.3× length of galea-lacinia, segment II apex without constriction ( Fig. 6E ); 4) segment II of labial palp with pointed and apically directed distomedial projection, segment III of labial palp rectangular, distal margin concave ( Fig. 6F ); 5) tarsal claws 0.6× length of tarsus, without row of denticles ( Fig. 7A ); 6) posterior margin of tergum IV with triangular, blunt spines ( Fig. 7C ); 7) abdominal tergum V with one lateral dark mark ( Fig. 1C ).

Redescription. Larva. Head. Antenna with minute spines and fine, simple setae on apex of each segment. Frons with two keels. Labrum ( Fig. 6A ): rectangular, broader than long; length about 0.5× maximum width; distal margin without shallow medial emargination; ventral surface with robust spine-like setae on distolateral and distal margins; dorsal surface with three to four short and blunt setae medially near distal margin; dorsal surface medially, near distal margin, with one row of long and thin setae. Right mandible ( Fig. 6B ): incisors deeply clefted into two sets; outer and inner set of incisors with 3 and 2–3denticles, respectively; prostheca slender, bifurcated at middle; margin between prostheca and mola concave; tuft of spine-like setae at base of mola absent; denticles of mola not constricted; lateral margin convex. Left mandible ( Fig. 6C ): incisors deeply clefted into two sets; outer and inner set of incisors with 5 and 3 denticles, respectively; prostheca robust, bifid at middle, inner lobe slender, outer lobe robust; margin between prostheca and mola concave; tuft of spine-like setae at base of mola absent; subtriangular process wide; denticles of mola not constricted; lateral margin convex. Hypopharynx ( Fig. 6D ): lingua subquadrangular, with one medial protuberance, and apical tuft of setae, subequal to superlingua; superlingua not expanded, with short, fine, simple setae scattered over distal margin. Maxilla ( Fig. 6E ): maxillary palp long, 1.38× length of galea-lacinia; segment II apex without constriction; maxillary palp with scarce fine and simple setae scattered over surface. Labium ( Fig. 6F ): glossa basally broad, narrowing slightly apically, longer than paraglossa; inner margin with one row of blunt setae; apex with three short spine-like setae; outer margin with six spine-like setae; ventral surface covered with thin setae. Paraglossa curved inward; apex with two spine-like setae; outer margin with one row of nine robust spine-like setae; dorsal surface with one longitudinal row of five robust spine-like setae near inner margin; ventral surface with one longitudinal row of five robust spine-like setae at middle. Labial palp with segment I 0.7× length of segments II and III combined; segment I covered with micropores (not illustrated); segment II with pointed and apically directed distomedial projection, apex of distomedial projection slightly concave, outer margin and distomedial projection covered with fine, long and simple setae; inner margin bare; segment III rectangular, length 0.5× width, covered with fine, long and simple setae on outer margin, ventral surface with two robust spine-like setae near distal margin, dorsal surface with one row of five robust spine-like setae, distal margin concave; external margin of segment III slightly concave or convex ( Fig. 6F ). Thorax. Foreleg ( Fig. 7A ). Femur: with row of nine short concave and blunt setae dorsally; apex with two concave and blunt setae (one illustrated); ventrally with two rows of elongated spine-like setae. Tibia: dorsally bare; ventrally with one row of nine short spine-like setae. Patella-tibial suture present, apparently restricted to ventral margin ( Fig. 7B ). Tarsus: dorsally bare; ventrally with one row of 12 short spine-like setae. Tarsal claws 0.6× length of tarsus, row of denticles absent. Abdomen: tergum V with lateral dark mark. Terga covered by scale-like triangular spines, micropores and short, fine and simple setae (not illustrated); posterior margin with triangular, blunt spines ( Fig. 7C ). Gills as in Figure 10 in Lugo-Ortiz & McCafferty (1997). Paraproct ( Fig. 7D ) with marginal spines, posterolateral extension with spines. Cerci with small lateral spines on all segments, paracercus without spines.

Material examined: Holotype, larva, Paraguay, Departamento de Cordillera, Piribebuy, Río Piribebuy , 3/ v/1985, R. T. Bonace, PERC . Paratype, larva, same data as holotype. One larva, same data as holotype .

Figures

FIGURE 1. Dorsal habitus. A. Apobaetis fiuzai holotype; B. Apobaetis fiuzai, abdominal details of a paratype; C. Apobaetis signifer holotype; D. Apobaetis signifer, abdominal detail of the holotype.

FIGURE 6. Apobaetis signifer. A. labrum (left d.v., right v.v.); B. right mandible; C. left mandible; D. hypopharynx; E. maxilla; F. labium (left d.v., right v.v.).

FIGURE 7. Apobaetis signifer. A. foreleg; B. detail patella-tibia suture, red arrow indicates the location of suture; C. posterior margin of tergum IV; D. paraproct.