Palaemnema mutans Calvert, 1931

Amaya-Vallejo, Vanessa & Novelo-Gutiérrez, Rodolfo, 2011, The larva of Palaemnema mutans Calvert, 1931 (Odonata: Platystictidae), Zootaxa 3049, pp. 59-63 : 59-62

Palaemnema mutans Calvert

Figs. 1–9

Material. One exuvia (1 ♂, reared), 22 F0 larvae (11 ♂, 11 ♀). COLOMBIA: Alto Anchicayá , Quebrada Acueducto (528 masl), 03.57025º N, 076.87815º W, 2-II-2009, (1 ♀); 3-II-2009, (2 ♀ 1 ♂); 29-I-2010, (2 ♂, 1 emerged on 3-II-2010); 5-I-2011, (5 ♂ 4 ♀); 6-I-2011, (4 ♂ 3 ♀), Alto Anchicayá, unnamed forest creek (538 masl), 03.57100º N, 076.87970º W, 11-IX-2008, (1 ♀), all V. Amaya leg. Six males and 5 females, including an emerged individual deposited in Colección Entomológica del Instituto de Ecología , A. C., Xalapa , Veracruz, México ( IEXA) .

Description. Exuviae light yellow, larvae dark brown dorsally, light brown laterally, and pale ventrally. Legs and cephalic lobes light brown. Anterior part of head, labrum, mandibles and apex of maxillae reddish-brown. Antennae yellowish-brown; head wider than thorax and abdomen, caudal lamellae saccoid, not petiolate ( Fig. 1).

Head. Slightly wider than long, flattened dorsoventrally, occiput widely concave. Compound eyes not prominent. Rows of long, hair-like setae arranged as follows: ventrolateral margin of compound eyes, surrounding the antennal scape, around three circular pale areas on the occiput, on interocellar spaces and on lateral margins of the head. Frons and apical margin of labrum covered with short, stiff setae. Antennae 7-segmented, 3 rd antennomere the longest, 7 th the shortest. Antennomeres 1–6 with long, hair-like setae on distal portion, surrounding the insertion of following antennomere, 7 with short hair-like setae on apex ( Fig. 2). Mandibles with a molar crest set in a soft, fleshy area, with the following formula (sensu Watson, 1956): R 1 2 3 4 0 a b; L 1 2 3 4 0 a (m1–7) b d, this last tooth sharply pointed. Molar lobe on left mandible usually with 9 teeth, but they could be 10, 11 or also 12; this lobe has a particular shape, divided in 2 portions: dorsal portion with a row of 5–8 small teeth, ventral portion with a fixed number of 4 larger teeth, giving the molar lobe a gapped appearance ( Fig. 3a, b). Prementum-postmentum articulation reaching posterior border of forecoxae. Prementum flat ventrally, longer than wide, sides strongly convex at middle. Lateral margins smooth and without setae. Dorsal surface with small transverse striae to each side of the midline. Ligula strongly protruding, with a row of small scales on apical border and a tuft of short, hair-like setae on each side, before insertion of labial palp; median cleft closed and well defined, with one minute spine on each side ( Fig. 4a). Labial palp with some long, hair-like scattered setae near base and below insertion of movable hook; its internal margin smooth and sharp, bluntly tipped, slightly curved to ligula, ending in two minute cusps; length of movable hook two-thirds length of internal margin of palp ( Fig. 4b). Hypopharynx deeply widened near last third of its length, widened borders with 4 long hair-like setae, and apical margin with 5–6 long hair-like setae on each side of median part, that part covered with scattered short setae ( Fig 5). Galeolacinia with 7 robust teeth, dorsal margin with 3 long, incurved teeth, 3 short teeth more incurved on ventral margin, apical tooth largest. Maxillary palp shorter than galeolacinia acutely pointed and covered with rows of short stiff setae ( Fig 6).

Thorax. Posterior margin of pronotum with row of long, hair-like setae, postero- lateral margins covered with same kind of setae. Mesepisternum covered with short setae, mesepimeron with some sparse setae and group of stiff setae surrounding wing insertion; mesinfraepisterna bare; metepimeron and metepisternum covered with sparse, short and long setae; metinfraepisterna bare. Legs long, hind tarsi extending beyond S10 when fully extended; all segments of all legs covered with long and short slender setae; fore tibiae with longer and denser setae than other tibiae; apices of tibiae bordered with row of short and stiff spines along internal margin, this margin slightly expanded on fore tibiae, and with spines more separated. External margin of fore tibiae with 3–4 robust spines intercalated with hair-like setae ( Fig 7). Fore femora not curved. Fore and hind wing buds reaching basal 0.75 and posterior margin of abdominal segment 5, respectively, and with short, stiff setae on margins.

Abdomen. Cylindrical and slender, without lateral spines or dorsal bumps. S4–10 covered with sparse, small, hair-like setae. Male gonapophyses lacking. Female gonapophyses slightly surpassing S10, all valves almost equal in size; ventral border of outer valves with row of short hairs ( Fig 8). Male cerci digitiform, blunt tipped, directed downwards in lateral view, convergent in ventral view, and as long as S10. Tergite coloration uniform, sometimes darker on S5–10. Epiproct shorter than paraprocts, external margins fully covered with long and abundant hair-like setae, ventral margin with hair-like setae only on apical half, increasing in size and number caudally, length of terminal filament 0.25 length of epiproct ( Fig 9a). Paraprocts grayish-brown, saccoid, not petiolate. External margins covered with scattered small setae that become longer and more abundant on terminal filament; length of filament more than half length of paraproct; widest part of paraproct at half its length without counting terminal filament ( Fig 9b).

Measurements (mm): Total length (without caudal lamellae) 9.8–12.9; maximum width of head 2.7–3.2; hind femur 2.8–3.1; male cerci 0.3–0.4; left paraproct with filament 5.0–6.2, right paraproct 4.8–5.4; epiproct with filament 3.2–4.4.

Habitat. Larvae of P. mutans were collected in tropical forest in shallow streams, among rough gravel and cobbles, in a stream section where the riparian vegetation was well preserved, with a closed canopy. Those streams are undisturbed, and the water has high levels of dissolved oxygen and an average temperature of 23°C.