Philogenia mangosisa

Tennessen, Ken J., 2008, Description of the female and nymph of Philogenia mangosisa from southern Ecuador (Odonata: Megapodagrionidae), Zootaxa 1787, pp. 63-68 : 65-67

Nymph of Philogenia mangosisa

( Figs 2 a–k)

Specimens Examined: One final instar exuviae (Ψ), and four final instar nymphs (2%, 2Ψ). Ecuador, Zamora Chinchipe Province, 3.6 km N of Guaguayme Alto; elev. 885m; 3 degrees 52’ 34"N, 78 degrees 53’ 33"W. 21 Aug. 2006, S. M. Bybee & K. J. Tennessen.

General body color dark brown without significant pattern, except meso- and metathorax dark brown ( Fig. 2 a).

Head. mottled brown, mostly dark ( Fig. 2 a), 4.8 mm wide (across compound eyes); eyes black dorsally, ventral submarginal row of stout tan spinules intermixed with fine setae ( Fig. 2 b). Labrum 1.95 mm wide, anterior margin slightly concave with scattered hair-like setae. Antenna 7-segmented, devoid of setae ( Fig. 2 d), 3.8 mm long; segments 1–4 amber, segments 5–7 fade from amber to light yellow toward tip; segment 2 approximately 1.7 times as long as segment 1; segment 3 longest, nearly 3 times as long as segment 1 and 1.55 times as long as segment 4; segment lengths (left antenna of reared): 0.39, 0.66, 1.15, 0.74, 0.45, 0.23, 0.12 mm (relative lengths adjusting segment 3 to a length of 1.00: 0.34, 0.57, 1.00, 0.64, 0.39, 0.20, 0.10). Prementum amber to tan ( Fig. 2 e), nearly covering entire ventral surface of head, 4.1 mm long, maximum width distal, 3.7 mm, minimum width near hinge, 1.8 mm; ligula convex ( Fig. 2 f), finely serrated along anterior margin, a small median cleft open at apical third to half; lateral margins of prementum serrate but without dorsal or ventral setae; labial hinge lying at transverse midline of procoxae. Palp with three large apical teeth, middle tooth largest, ventral one smallest ( Fig. 2 g), without setae dorsally, external margin serrated, ventral margin bearing numerous, fine, short pale setae along lateral margin and one long (0.45–0.48 mm) pale seta just proximal to base of movable hook; movable hook stout, not sharply tipped, slightly curved, about 0.75 times length of palp. Mandibles with following formula sensu Watson (1956): L 1234+5 0 a (m1) b, R 1234 y a (m0) b.

Thorax. pronotum slightly raised anteriorly on either side of median line, hind margin broadly convex; propleural process and procoxa with a row of stout spinules along lateral edge and with a rough covering of serrate processes, more pronounced on procoxa ( Fig. 2 h); legs pale brown; profemur with a serrate dorsal ridge, two dorsal serrate carina, and two lateral ridges extending to roughly half the femur length and composed of serrate protuberances with many short stout setae ( Fig. 2 h); meso- and metafemora laterally flattened, without any noticeable markings in dorsal view, but with a dorsal carina and two serrate, ventral carinae; metafemur extending to S7. Hind wing pad extending to posterior portion of S6; fore wing pad extending slightly past anterior margin of S6; fore wing pad 6.3 mm long.

Abdomen. no postero-lateral spines on any segments; 6–14 short, fine setae scattered along ventro-lateral carinae of S3-S10, 4–6 longer setae on S8 and S9. Female cerci triangular, projecting directly posteriorly, tips acute; male cercus curved downward in lateral view, tips indented ( Fig. 2 j), directed inward in posterior view, 0.06 mm long, tips blunt and slightly indented ( Fig. 2 j); two thin, pale, flap-like structures between bases of paraprocts ( Fig. 2 j), originating beneath tips of cerci, covering anal opening and extending ventrad to slightly beyond ventral margin of S10. Gills brown violet with pale, filamentous, setose tips; median gill and its terminal filament slightly longer than lateral gills ( Fig. 2 k).

Measurements (mm). Total length 15.5–16.0; head width 4.5–4.6; metafemur length 5.3–5.6; abdominal length 8.0–8.1; abdominal width (measured at S3) 2.75–2.9; median gill length 7.0; lateral gill length 7.1.

Diagnosis. Female. The female of P. mangosisa is distinct from the sympatric P. redunca Cook in the morphology of the prothoracic hind lobe. In P. mangosisa , the ventro-lateral extremity of the hind lobe extends ventrally over the proepimeron as a narrow pale lobe ( Fig. 2 ); in P. redunca , the lower part of the hind lobe is reduced. The proepimeron of P. mangosisa lacks a posterior protuberance ( Fig. 2 ), whereas P. redunca possesses a robust, posteriorly-directed protuberance on the epimeron (see Cook 1989; Figs. 5 and 6 showing this protuberance covering the reduced lower extremity of the hind lobe in lateral view). We saw no difference in color pattern between both species. Cook (1989) based the description of P. redunca on over 20 females from Napo, Morona-Santiago, Pastaza and Tungurahua provinces, although none was taken in copula with a male. Cook correctly associated females of P. redunca based on a recently collected pair taken in copula ( ECUADOR, Pastaza Prov., seep along Río Metolo, Los Copales near Mera, 20 Sept. 2005, coll. K. J. Tennessen).

Separation of the female of P. mangosisa from other species is more difficult. According to Bick & Bick (1988), P. mangosisa belongs to the margarita species-group whose males of the four species share similar caudal appendage morphology. Males of two ( P. mangosisa and P. peruviana Bick & Bick, 1988 ) possess hyaline wing tips whereas males of the other two (P. e l i s a b e t a Calvert, and P margarita Selys ) possess brown wing tips. Due to similar male appendage morphology, one might suspect females of P. mangosisa to approach females within this group. The female of P. peruviana is unknown, however pronotal morphology among the three remaining species is similar. The hind pronotal lobe of the holotype of P. m a rg a r i t a ( Fig. 1 c) is dark and extends ventrally only as far as the suture between the notum and the epimeron. The hind pronotal lobe in P. mangosisa ( Fig. 1 b) is pale and extends ventrally beyond the notal suture. According to Calvert (1924), the hind margin of the pronotum of P. elisabeta (which has dark wing tips) also extends ventrally so as to apparently form the hind margin of the upper third of the epimeron. However, the hind lobe of the pronotum of P. e l i s a b e t a, in antero-dorsal view, is entirely rounded ( Calvert, 1924, Fig. 8), unlike that of P. mangosisa which is slightly indented laterally ( Fig. 1 a).

Nymph. The large prementum of Philogenia nymphs, which projects antero-laterally beyond the head in dorsal view ( Fig. 2 b) is an unusual feature within Zygoptera but present in several megapodagrionid genera. The third antennomere in Philogenia is much longer than any of the other segments (similar condition exists in Platystictidae and Protoneuridae and many families of Anisoptera) and there is a row of stout spinules extending the length of the venter of the compound eye (similar spinules exist in other megapodagrionid genera but do not extend the entire length of the eye). The unusual, pale anal flaps in Philogenia are also present in Paraphlebia Selys , and Rhipidolestes Ris. The nymph of P. mangosisa compares closely with the few available descriptions of other species in the genus. In the key by Ramírez-Ulate and Novelo-Gutiérrez (1994), nymphs of P. mangosisa key to P. t e r r a b a Calvert, 1907 based on antennal segment 3 being much shorter than segment 4–7 combined. The ligula of P. mangosisa is partly open distally, but it is straight-sided, not v-shaped as in P. t e r r a b a. The description of P. cassandra Hagen in Selys, 1862, by De Marmels (1982) was not detailed enough to deduce differences between it and P. mangosisa . De Marmels (pers. comm..) states that the antenna of P. cassandra shows that segment 4 has about 1.4 times the length of segment 5, whereas in P. mangosisa , segment 4 is about 1.6 times as long as segment 5. Further, antennal segment 3 for P. cassandra is about four times the length of segment 1 whereas segment 3 is approximately three times the length of segment 1 in P. mangosisa . The ligula of P. mangosisa is similar to that of P. carrillica , but it is slightly open apically in the latter species.

Habitat notes. The nymphs were collected from a small, shallow stream with a gravel/sand/mud-bottom substrate no more than 0.5 m across and no more than 10 cm deep. The stream was well-shaded by woody vegetation and is likely permanent. The stream was devoid of large rocks but it had an abundance of leaf and branch litter and supported a good community of small aquatic invertebrates. Most of the nymphs were collected in the leaf litter directly under the spillway of small drops in stream elevation. Flow was fairly strong, and was fed by a small waterfall approximately 2 m high. The stream was steeply graded and rapidly descended to feed a larger stream; no nymphs were found in the larger stream. We found nymphs of P. mangosisa to be locally distributed, since other similar streams yielded no Philogenia nymphs except for one taken under a large log at the edge of a waterfall-fed pool about 4 m in diameter.

Figures

FIGURE 1. Philogenia mangosisa adult female, prothorax in dorsal view (a) and lateral view (b) with arrow indicating the diagnostic hind lobe ventral extremity; (c) line drawing of hind lobe ventral extremity from holotype of P. margarita, based on a photograph from J. Constant of IRSNB.

FIGURE 2. Philogenia mangosisa nymph; a) male nymph, lateral view; b) head, dorsal view; c) venter of compound eye, showing row of stout spinules; d) left antenna of reared?; e) prementum, ventral view; f) prementum; g) labial palp of reared?; h) stout sharp setae and scale setae on proepimeron, procoxa, and profemur, dorsal view; i) left male cercus, lateral view; j) male cerci and pale anal " flaps ", posterior view, gills removed; k) median gill, lateral view.