The Plecoptera of Panama. IV. Description of the last nymphal instar for two species of Anacroneuria Klapálek (Plecoptera: Perlidae) from the Caldera River, Chiriquí, Panamá Author Castillo Sánchez, Kayla N. Author Aguirre, Yusseff P. Author Ríos González, Tomás A. Author Bernal Vega, Juan A. text Zootaxa 2019 2019-12-17 4711 3 446 458 journal article 24568 10.11646/zootaxa.4711.3.2 08d3223a-3afc-47e8-ac59-634f4e4b59d1 1175-5326 3586528 0E29F571-BA60-4F77-9174-4BF0FB3A688F Anacroneuria planicollis Klapálek, 1923 ( Figs. 2–12 ) Material examined: Panamá : Chiriquí , Jaramillo Abajo, Caldera River, 1065 masl , 8°44’46.97”N and 82°25’8.77”O . 1 n, 04.ii.2015 , #17; ibid., 1 n, 04.ii.2015 , #19; ibid., 1 n, 04.ii.2015 , # 22; ibid., 1 n, 21.ii.2015 , #23;1 n, 21.ii.2015 , #24;1 n, 21.ii.2015 , #25;1 n, 21.ii.2015 , #26;1 n, 21.ii.2015 , #27;1 n, 21.ii.2015 , #28;1 n, 21.iii.2015 , #48; ibid., 1 n, 21.iii.2015 , #49; ibid., 1 n, 21.iii.2015 , #50; ibid., 1 n, 21.iii.2015 , #51; ibid., 1 n, 21.iii.2015 , #52; ibid., 1 n, 21.iii.2015 , #53; ibid., 1 n, 21.iii.2015 , #54; ibid., 1 n, 25.iv.2015 , #99; ibid., 1 n, 25.iv.2015 , #100; ibid., 1 n, 24.viii.2015 , #190;1 n, 17. ix.2015 , #196; ibid., K. Castillo , MUPADI (nymphs: m # 1, f # 1, adults: m # 2, f # 16) . Adult : Description by Stark (1998) . Description of the last nymphal instar . Male (n=3): Body brown and stout, body length 12.3 ± 0.23 mm (not including cerci) ( Fig. 2 ). Head (length = 1.9 ± 0.17 mm , width = 2.9 ± 0.26 mm ): mostly brown, with a dark spot in dorsal view that extends from the back of the ocelli to the middle part of the head. Light colored ocelli with dark margins and a clear area extended laterally, front with a clear and discontinuous M-shape spot, brown labrum ( Fig. 3 ), filamentous antennae (length: 7.5 ± 1.10 mm ) with dark hairs in the proximal region of the scape ( Fig. 4 ). FIGURES 2–4. Nymph of Anacroneuria planicollis (male). 2. Body, dorsal view, 3. Head, dorsal view, 4. Antenna, dorsal view. (hd: head, th: thorax, ad: abdomen, pr: pronotum, lbr: labrum, ant: antenna, e: eye, scale: 1.0 mm). Thorax (n=3): Pronotum (length = 1.6 ± 0.11 mm , width = 2.9 ± 0.21 mm ) with band pattern (dark, light, dark, light) from the midline to the lateral margin of the pronotum, pronotal margin clear with spines ( Fig. 3 ). Mesonotum (length = 2.6 ± 0.73 mm , width = 32 ± 0.21 mm ) and metanotum (length = 2.6 ± 0.17 mm , width = 2.7 ± 0.23 mm ) with pattern of clear, diffuse drawings, wing pads dark in nymphs closed to emerge, with spines in the margins ( Fig. 9 ). Thoracic gills: sc1 present, sc2 and sc3 absent; pl1, pl2 and pl3 present ( Fig. 10 ). Legs mostly brown, covered with dark hairs and outer side margins with few fringes of bristles. Foreleg ( Figs 5–6 ): coxa with numerous dorsal spines in the distal region and without ventral spines ( Fig. 8 ). Femur covered with dark hairs, with a transverse row of spines (7 to 8) in the middle part and a patch of small spines in the proximal lower part, presence of a dark spot at the distal end, without ventral distal spines ( Fig. 7 ). Abdomen: Brown tergites with long, strong spines, presence of a circular brown spot in the ninth sternite ( Fig. 11 ), anal gills absent, cerci with few fine bristles at the distal end. FIGURES 5–8. Prothoracic Anacroneuria planicollis (male). 5. Prothoracic leg, dorsal view, 6. Foreleg, ventral view, 7. Femur, dorsal view, 8. Coxa, ventral view. (cx: coxa, tr: trochanter, fm: femur, scale: 1.0 mm). Variations Female (n=11): Body characteristics similar to those of the male. Body length 16.1 ± 0.82 mm (does not include cerci, n = 3), antennas: n = 10, long = 7.55 ± 2.69 mm , head: long = 2.42 ± 0.17 mm , width = 3.71 ± 0.21 mm , pronotum: long = 2.15 ± 0.08 mm , width = 3.77 ± 0.28 mm , mesonotum: long = 3.23 ± 0.24 mm , width = 4.08 ± 0.32 mm , metanotum: long = 3.31 ± 0.16 mm , width = 3.68 ± 0.25 mm , inverted V-shaped notch in the eighth sternite ( Fig. 12 ). Diagnosis : The nymphs of A. planicollis can be distinguished from A. quetzali , by the presence of a dark spot on the head in dorsal view that extends from the back of the ocelli to the middle part of the head, presence of pattern of bands from the midline towards the lateral margin of the pronotum, coxa without ventral spines, and femur with a transversal row of spines (7 to 8) medially. Distribution : Belize , Costa Rica , Guatemala , México , Nicaragua , and Panamá . Ecology : The nymphs of A. planicollis were collected in a shallow area of the Caldera River with bedrock substrate, submerged leaf litter, and slow current. The nymphs of A. planicollis were positively correlated with temperature and conductivity ( Castillo Sánchez et al., 2018 ).