Perilestes attenuatus Selys, 1886

Neiss, Ulisses Gaspar & Hamada, Neusa, 2010, The larva of Perilestes attenuatus Selys, 1886 (Odonata: Perilestidae) from Amazonas, Brazil, Zootaxa 2614, pp. 53-58 : 54-57

Perilestes attenuatus Selys, 1886

Figures: 2–15

Diagnosis: ligula with one pair of tubercles; abdominal S3–10 with lateral spines; median line of tergites 4–10 with hooks.

Larva: body elongated, especially abdomen; disruptive color pattern, with dark brown and pale spots; legs with alternating pale and brown bands ( Fig. 2 ).

Head: trapezoidal in shape ( Fig. 2 ), flattened dorso-ventrally, about 1.8–2.1 times as wide as long, with posterior margin concave, cephalic lobes pronounced and rounded with small spines on the posterior margin. Ocellus well marked, surrounded by black. Anterior margin of labrum concave in the middle with small setae along its length. Antenna 7-segmented, more than twice as long as head length; fourth antennomere the longest; first, second, fourth, fifth and sixth antennomere ochraceous in color, with a median band pale; third antennomere, pale, with distal 2/3 light brown; seventh antennomere all pale ( Fig. 7 ). Relative size of antennomeres (mm): 0.47, 0.71, 0.64, 0.8, 0.4, 27, 0.13. Prementum-postmentum articulation reaching base of third coxa; in the exuviae this articulation surpasses base of second coxa; postmentum with a dark brown spot on latero-apical margin. Prementum, long, width 0.52–0.56 times its length, slightly concave and constricted at basal half, with dorsal surface and external margin bare; ligula slightly convex, crenulated along distal margin, crenulations short and blunt; median cleft deep, surpassing basal margin of ligula, sides parallel, and with a small blunt tubercle on each side of the median cleft ( Fig. 8 ). Labial palp short, with three sharp teeth, median tooth longest, inner tooth shortest. Labial palp without spines or setae on dorsal surface and outer margin; inner margin serrulate ( Fig. 10 ). Mandibular formula: L 1’1234 0 a(m12345)b, R 1’1234 y b ( Fig. 9 ). Maxilla with four teeth long and curved on the inner side; apical tooth with three supplementary teeth.

Thorax: prothorax small, quadrangular, with lateral angles of distal margin pronounced and rounded on each side ( Fig. 2 ). Wing pads reaching half of abdominal segment 4; in exuviae, wing pads reaching half of abdominal segment 3. Legs with pale and dark bands ( Fig. 2 ); coxa with brown spot on antero-lateral and dorsal regions; trochanter pale with a brown band on the median region; femur with two brown bands and apical region with a dorsal brown spot; tibia with two brown bands. Apical ventral region of tibia with group of very short, simple spines; tarsus 3-jointed, with two rows of ventral setae, longer in hind leg, tarsal claws simple and sharp.

Abdomen: elongated, segments with similar color pattern ( Fig. 2 ); lateral spines on S3–10; spines on S3– 4 smaller than others ( Fig. 11 ). Median line on tergites 4–10 with a row of spines/hooks; additionally, tergite 4 with 1–3 distal spines. Spines on the median line of tergites increasing in size in antero-posterior direction; area between spines with numerous thin setae ( Fig. 12 ). Tergite 10 with two divergent spines, pointed dorsally at median region of posterior margin ( Fig. 3 ). Sternite 10 with two spines on the distal margin, one on each side of median line ( Fig. 4 ). Male gonapophyses small, conical and sharp, not surpassing distal end of S9 ( Fig. 4 ). Male with a mark of developing secondary genitalia under abdominal S1 and S2 ( Fig. 13 ). Female gonapophyses surpassing distal end of S10; external lobes with small spines laterally ending in a sharply pointed projection ( Fig. 5 ). Caudal lamellae foliate, with short petiole and main tracheal branch and ramifications evident; tracheal branch with spines on basal half; presence of spiniform setae on the dorsal and ventral margins until distal third; coloration brown with basal, medial and sub-apical pale outer spots, distal region pale, almost transparent ( Fig. 6 ); median lamella similar but slightly shorter than lateral ones. Female cercus with apex pointed ( Fig. 14 ), male cercus elongated with apex rounded ( Fig. 15 ), both curved dorsally.

Measurements (in mm; females N = 1, males N = 3): Total length (without gills), female: 13.5, males: 13.5–16.5; head length, female: 1.58, male: 1.4; head width, female: 2.8, male: 2.7–2.8; antenna, female: 3.6, male: 3.2–3.5; prementum length, female: 3.1, male: 2.7–2.8; prementum max. width, female: 1.6, male: 1.5; hind wing pads, female: 3.6, male: 3.5–3.6; fore wing pads, female: 3.75, male: 3.8–3.9; femur, female: F1: 1.9, F2: 2.5, F3: 3.2, male: F1: 1.7–1.9, F2: 2.2–2.5, F3: 2.8–2.9; tibia, female: T1: 2.1, T2: 2.5, T3: 3.1, male: T1: 1.8–2, T2: 2.1–2.3, T3: 2.6–2.9; cercus, female: 0.4, male: 0.6; median caudal lamellae, female: 3.1, male: 2.6–2.8; lateral caudal lamellae, female: 3.4, male: 3.2–3.4.

Material examined. BRAZIL: AMAZONAS state: Manaus: highway BR 174–Km 25, ramal Quinta da Boa Vista Km 6, igarapé (02º44'42.7"S / 60º 00'00.6"W): last-instar larva 1 female, 27.v.2008, two male exuviae (last-instar larvae collected 27.v.2008 emerged 30.v.2008 and 5.vi.2008); Reserva Florestal Adolpho Ducke, highway AM 010–Km 26 (2º57'07.4"S / 59º 57'27.6"W): Igarapé Acará 23: last-instar larva 1 male, Igarapé Acará 22: 1 adult male, 15.v.2008, Igarapé Bolívia 13, 1 adult male, 26.v.2008, 1 adult male, 6.xi.2008; highway BR 174–Km 56, ramal ZF02 Km 38, LBA station, igarapé (2º35'50.9"S / 60º 12'54.9"W): 1 adult male, 22.v.2008; highway BR 174–Km 38, Fazenda Experimental da UFAM, PPBio grid, igarapé (2º39'29.8"S / 60º 4'28"W): adults: 1 male and 1 female in tandem, 10.xi.2008; Presidente Figueiredo: highway AM 240–Km 13, Sítio da Maroca, igarapé (2º00'55.7"S / 59º 51'32.6"W): 1 adult male, 18.iv.2008; Novo Airão: highway AM 352: Km 10, Fazenda Valdemar, igarapé (2º42'49.5"S / 60º 54'45.2"W), 1 adult female, 12.viii.2008; Km 24, Mercuri Hotel, stream at the second bridge (2º50'44.4"S / 60º 54'56.9"W), 1 adult male, 19.viii.2008; Manacapuru: highway AM 352: Km 66, Comunidade Nova Esperança, fourth stream (3º2'41.7"S / 60º 46'12.1"W), 1 adult male, 5.ix.2008; Km 75, Sítio Sr. Pereira, stream (3º4'58.2"S / 60º 44'7.8"W), 1 adult female, 10.ix.2008; all Neiss, U. G. leg.

Remarks. The larva of P. attenuatus can be distinguished from that of P. fragilis , the only other species of which the larva has been described, by the presence of a pair of tubercles on the ligula (absent in P. fragilis ) and by the arrangement of the spines and hooks on the abdominal segments: lateral spines on S3–10 and dorsal hooks on the median line of S4–10 (lateral spines on S4–10 and dorsal hooks on S 5–10 in P. fragilis , respectively) ( Santos 1969). As Williamson & Williamson (1924) reported for Perilestes , the larva and adult of P. attenuatus are forest stream dwellers, inhabiting streams with sandy beds with plant detritus, especially leaves.

Perilestes attenuatus occurs in Bolivia and Brazil; in the latter, this species has been reported in the states of Amazonas (Manaus), Pará (Santarém) and Rondônia (Porto Velho) ( Williamson & Williamson 1924). Our study increases the known range for the species in the state Amazonas to the municipalities of Novo Airão, Manacapuru and Presidente Figueiredo.

Figures

FIGURES 2 – 6. Perilestes attenuatus (Odonata: Perilestidae): 2) female larva in dorsal view; Last abdominal segments: 3) two dorsal divergent spines (indicated by an arrow), pointed upward on the median region of posterior margin; 4) male gonapophyses, ventral view; 5) female gonapophyses, left lateral view; 6) left lateral caudal lamellae. (Scale bar: 1 mm)

FIGURES 7 – 15. Perilestes attenuatus (Odonata: Perilestidae), last-instar larvae (♂, Ψ): 7) antenna; 8) prementum, dorsal view; 9) left (L) and right (R) mandibles, inner side; 10) palp, dorsal view; 11) abdomen, S 3 – 10, dorsal view, arrow indicates lateral spines; 12) abdomen, S 4 – 10, in right lateral view, arrow indicates dorsal hooks on the median line; 13) mark of accessory genitalia on venter of abdominal S 1 and S 2 of male; Cercus, lateral side: 14) female, 15) male. (Scale bar: 1 mm).