Apobaetis irai, De Lima & Massariol & Cruz & Hamada, 2022

De Lima, Cláudia R. T., Massariol, Fabiana Criste, Cruz, Paulovilela & Hamada, Neusa, 2022, Two new species of small minnow mayfly (Ephemeroptera: Baetidae) from a mine-tailing dam disaster area in Minas Gerais, Brazil, Zootaxa 5196 (2), pp. 265-279 : 268-272

Apobaetis irai sp. nov.

urn:lsid:zoobank.org:act:478FF6A7-7426-41D6-9EDD-213E696AB749

( Figures 3A–C ; 4A–G ; 5A–G )

Material examined. Holotype. Larva (on slide), BRAZIL, Minas Gerais State, Ipaba, Rio Doce 42º25′33″W, 19º22′20″S, 26.VIII. 2018, 210 m. a.s.l., coll. Bramuth A.C. ( INPA) . Paratypes: 2 larvae (on slide), same data as holotype ; 3 larvae (on slide), same data as holotype, except 13.II.2019 ; 2 larvae (on slide), Minas Gerais State, Marliéria, Rio Doce , 42º30′08″W, 19º41′42″S, 31.I. 2019, 247 m .a.s.l., coll. Bramuth A.C., Massariol F.C., ( INPA).

Description. Larva. Body length 3.1–3.4 mm. Coloration of light yellow with shorts brown marks over terga.

Head. Antenna: flagellum with minute spines on apex of each flagellomere. Labrum ( Figs 4A, B ): rectangular, length about 0.6 × maximum width; distal margin without medial emargination; ventral surface with one row of 14 spine-like setae on distolateral and distal margins, distal margin with medial spine-like setae; dorsal surface, at distal medial margin, with 3 minute, blunt and spatulate setae, with one medial row of long thin setae and many thin setae over surface. Left mandible ( Fig. 4C ): incisors cleft, outer and inner set of incisors respectively with 4+3 denticles; prostheca robust, bifid, inner lobe with outer margin pectinate; margin between prostheca and mola concave, subtriangular process wide and pointed, with large spine on outer margin; tuft of spine-like setae at base of mola present; denticles of mola not constricted; mola with two large denticle; outer margin convex. Right mandible ( Fig. 4D ): incisors cleft; outer and inner set of incisors respectively with 3+2 denticles; prostheca thin, bifurcated at apex, outer lobe pectinate; margin between prostheca and mola concave; tuft of spine-like setae at base of mola absent; denticles of mola not constricted; apex of mola with one simple setae; process of mola triangular; outer margin convex. Hypopharynx ( Fig. 4E ): lingua subquadrangular, longer than superlingua, without distomedial projection, tuft of setae at apex; superlingua rounded, with short, thin, simple setae scattered over distal margin. Maxilla ( Fig. 4F ): maxillary palp 2.3 × length of galea-lacinia; segment I subequal in length of galea-lacinia; segment II robust, covered by thin setae; inner margin of galea-lacinia with two spine-like setae. Labium ( Fig. 4G ): glossa with parallel margins, apex with inner margin concave, same length of paraglossa; dorsal surface with 3 small spine-like setae at apex, one transverse row of 13 robust spine-like setae on apical third; ventral surface covered by thin long setae. Paraglossa curved inward; dorsal surface with 1 long and robust spine-like setae at apex, apical third with one row of 3 long and robust spine-like setae, near inner margin with one row of 7 long and robust spine-like setae; outer margin with one row of 24 long and thin spine-like setae from base to apex; ventral surface with one row of 6 long and robust spine-like setae at middle. Labial palp with segment I 0.6 × length of segments II and III combined; segment I covered by micropores (not illustrated); segment II with outer margin covered by long thin setae, inner margin bare, inner distal protuberance of segment II rounded and expanded, covered with thin, long simple setae; segment III triangular, covered by thin simple setae, length 0.8 × width, outer margin covered by long thin setae; dorsal surface with 7–9 robust spine-like setae on distal margin; ventral surface with 5 robust spine-like setae on distal margin.

Thorax. Foreleg ( Figs 5A, B ). Femur: dorsal margin with one row of 12–14 short, blunt and spatulated setae, apex with a pair short, blunt and spatulated setae; anterior surface with one row of 11–13 short, blunt and spatulated setae near to dorsal margin, and one row of small spine-like setae near to ventral margin; posterior surface with one row of 11–12 short, blunt and spatulated setae near dorsal margin; ventral margin with one row of 11 short spinelike setae. Tibia: dorsal margin bare, ventral margin with one row of 8–10 short spine-like setae; patella-tibial suture present. Tarsus: dorsal margin bare, ventral margin with one row of 9–10 short spine-like setae. Claws 1.0–1.2 × length of tarsus, without denticles. Middle and hind legs similar to foreleg.

Abdomen ( Figs 3A–C , 5C–G ). Coloration light yellow with tergum IV–X with an anterolateral mark, II–VIII with a medial mark, VII–VIII with an anteromedial mark; sterna light yellow. Terga creased with micropores; posterior margin of tergum IV with regular, triangular and pointed spines ( Fig. 5C ). Gills ( Fig. 5D ) with rounded apex, longer than next segment, with one medial trachea pigmented. Paraproct ( Fig. 5E ) with eight marginal spines, posterolateral extension without spines. Cerci ( Fig. 5F ) with lateral spines on every segments, longer on every 2 nd segment. Paracercus ( Fig. 5G ) without spines.

Imagoes: Unknown.

Etymology. In the native South American language Tupi-guarani, irai means “honey water”, in allusion to the name of the type locality (Doce in Portuguese means “sweet”); the specific epithet should be considered a noun in apposition.

Diagnosis. Larva: 1) labrum rectangular, distal medial margin with 3 minute, blunt and spatulate setae ( Fig. 4A ); 2) maxillary palp longer than 2.3 × length of galea-lacinia, segment I 1.2 × length of galea-lacinia ( Fig. 4F ); 3) glossa with parallel margins, apex with concave inner margin ( Fig. 4G ); 4) inner distal protuberance of segment II rounded and expanded ( Fig. 4G ); 5) segment III triangular ( Fig. 4G ); 6) patella-tibial suture present ( Fig. 5A ); 7) claws 1.0–1.2 × length of tarsus ( Fig. 5A ); 7) paraproct without spines in posterolateral extension ( Fig. 5E ).

Comments. Apobaetis irai sp. nov. is very similar to the species recently described for Rondônia, northern of Brazil, A. biancae Cruz, Boldrini & Hamada and A. jacobusi Cruz, Boldrini & Hamada (South America), sharing almost all the diagnostic features described in Cruz et al. (2020), can also be confused with species A. lakota McCafferty of North America (McCafferty 2000), the four species have rounded and expanded medial projection of segment II and triangular segment III of the labial palp.

The new species can be distinguished from A. lakota by the hypopharynx, with lingua subquandrangular in A. irai sp. nov. with tuft of setae at the apex, while A. lakota has lingua subcircular with a median lobe, without a tuft of setae; A. irai sp. nov. has glossae with concave inner margins at apex, inner margin without setae, and subequal in length to paraglossa; in A. lakota the glossa narrows slightly in the distal portion, has a rounded apex, with setae on inner margin, and longer than paraglossa.

The A. irai sp. nov. can be distinguished from A. jacobusi and A. biancae by the setae in the distal middle area of the dorsal surface of the labrum, which are three, minute, blunt and spatulate setae in A. irai sp. nov., four, strong and pointed in A. biancae , while A. jacobusi has two protuberances and a row of thin and long setae. Apobaetis irai sp. nov. has glossa subequal in length to the paraglossa, while in A. jacobusi and A. biancae the glossa is longer than paraglossa; A. irai sp. nov. differs from A. jacobusi and A. biancae by the size of the claws, with 1.0–1.2 × the length of tarsus in A. irai sp. nov., in A. biancae the claw is 1.4 × the length of tarsus and in A. jacobusi the claw is subequal to the tarsus; A. irai sp. nov. has no spines on the paracercus, A. jacobusi and A. biancae have lateral spines on all segments of the paracercus.

Figures

FIGURE 3. Apobaetis irai sp. nov. holotype (INPA). A, dorsal habitus of larvae female; B, lateral view; C, ventral view.

FIGURE 4. Apobaetis irai sp. nov. holotype (INPA). A, labrum (left d.v., right v.v.); B, labrum (detail of median setae); C, left mandible; D, right mandible; E, hypopharynx; F, left maxilla; G, labium (left d.v., right v.v.).

FIGURE 5. Apobaetis irai sp. nov. holotype (INPA).A, foreleg (anterior surface), detached setae are posterior surface; B, detail of forefemur; C, posterior margin of terga IV; D, gill; E, paraproct; F, cercus; G, paracercus.