Psaironeura tenuissima (Selys, 1886)

Mendoza-Penagos, Cristian Camilo, Juen, Leandro, Neiss, Ulisses Gaspar, Hamada, Neusa & Muzón, Javier, 2023, Description of the final-instar larva of Psaironeura tenuissima (Odonata: Zygoptera: Coenagrionidae) from Amazonia, International Journal of Odonatology 26, pp. 197-204 : 198-202

publication ID	https://doi.org/10.48156/1388.2023.1917238
persistent identifier	https://treatment.plazi.org/id/03F02E49-FFFE-FB0D-EE44-FF12FE6CF78D
treatment provided by	Felipe
scientific name	Psaironeura tenuissima (Selys, 1886)
status

Treatment

Description of the final-instar larva of Psaironeura tenuissima (Selys, 1886) View in CoL ( Figs 1−4 View Figure 1 View Figure 2 View Figure 3 View Figure 4 )

Examined material

Five exuviae (3 ♂, 2 ♀, reared), 5 F-0 larvae (5 ♂). BRA- ZIL: Pará state: Goianésia, Cickel ,lateral ponds in stream of the first order (- 3.709 S, - 48.561 W, elevation 159 m), 03 August 2021 (1 ♂, 1♀, emerged 05 September 2021, 10 September 2021, respectively); 08 August 2021 (1 ♀ emerged 08 September 2021) Hamada Neusa, Pes Ana, Desiderio Gleison, da Silva Jeferson, Mendoza-Penagos Cristian, leg. GoogleMaps ; Paragominas , first order stream (- 3.086 S, - 47.687 W, 50 m), 13 August 2021 (1 ♂, emerged 10 September 2021) Hamada Neusa, Pes Ana, Desiderio Gleison, da Silva Jeferson, Mendoza-Penagos Cristian, leg. GoogleMaps ; Magalhaes Barata, Calafate , stream of first order (- 0.863 S, - 47.668 W, 20 m), 26 September 2021 (5 ♂ F-0), Mendoza-Penagos Cristian, leg. GoogleMaps ; Amazonas state: Presidente Figueiredo, Uatumã Biological Reserve, next to Balbina village , PPBio grid: N.S. 4– 2.600 m, first order stream, larva collected in stack of leaves in a backwater (- 1.802 S, - 59.246 W, 120 m), 25 September 2009 (1 ♂, emerged 02 October 2009) U.G. Neiss leg. GoogleMaps

Description

Larva. Slender, dark brown coloration, legs pale yellow with two dark brown bands on femora. Caudal appendages lamellate, basal part sclerotized, apex membranous ( Figs 1a–b View Figure 1 ).

Head. subpentagonal, elongated transversally, as wide as 1.5 long ( Fig. 1a View Figure 1 ). Labrum ventral margin concave at center, with six spiniform setae; clypeus dark brown with a medial pale spot. Occipital margin concave, occipital lobes rounded and strongly projected laterally with a row of marginal five–six claviform setae. Antennae ( Fig. 2a View Figure 2 ) with seven segments, yellowish with a dark brown spot at base of antennomeres 3 th, 4 th and 6 th; 3 rd antennomere the longest, size proportions of antennomeres: 0.40, 0.60, 1, 0.70, 0.50, 0.40, 0.30. Maxilla’s ( Fig. 2b View Figure 2 ) galeolacinia with eight teeth, four dorsal teeth slightly incurved, and three ventral teeth varying in size and robustness, maxillary palp gently incurved. Prementum reaching the procoxae, two premental setae on each side of midline; lateral margins slightly concave, each with a row of I– VI setae; distal margin projected and finely serrulated, with a minute tubercle on each side of the midline ( Fig. 2c View Figure 2 ). Labial palp ( Figs 2d–e View Figure 2 ) with 6 setae on the dorsal margin; movable hook slightly curved, sturdy, and sharply point- ed; apical lobe truncated, with three small teeth on the basal margin and minute denticles on the distal margin; anterior margin with terminal hook well developed, as long as 0.5 times the length of the movable hook; internal margin slightly serrated. Mandibles ( Figs 2f–g View Figure 2 ) with three setae on the external margin; mandibular formula: L 1’1234 y ab / R 1’1234 y a.

Thorax. Pronotal disk subtrapezoidal ( Fig. 1a View Figure 1 ), lateral pointed projection weakly pronounced. Legs short, posterior tibiae not reaching the margin of S10 ( Fig. 1a View Figure 1 ). Coxae dark brown. Femora pale yellow with two dark brown bands, one submedial and one distal ( Fig. 3a View Figure 3 ). Tibiae pale yellow with a medial dark brown band. Tarsi pale yellow. Femora with concave setae ( Figs 3b–e View Figure 3 ), distributed on the extensor and flexor margins. Tibiae with intercalated trifid ( Fig. 3d View Figure 3 ) and pectinated ( Fig. 3e View Figure 3 ) setae on the distal ventral surface. First and second tarsomeres with four ventral rows of setae (simple, trifid and pectinated, as on tibiae), two medial and two lateral; third tarsomere almost as long as long as the remaining tarsomeres together, with two ventral rows of setae. Tarsal claws simple, thin, and curved apically. Wing pads reaching the median region of S5 (S6 on larval exuviae).

Abdomen. Short and cylindrical; posterior margin armed with setae as follows: S5 laterally, S6–9 increasing dorsally, and S10 completely ( Fig. 3f View Figure 3 ). Male gonapophyses ( Fig. 3g View Figure 3 ) conical, divergent, and sharply pointed, extending beyond the distal margin of S9; their bases separated from each other by a gap matching the length of the gonapophyses. Male cerci globose, apex strongly downcurved ( Fig. 3h View Figure 3 ). Female gonapophyses ( Fig. 3i View Figure 3 ) well developed, extending beyond the posterior margin of S10; lateral valves with acute apexes, central and dorsal valves smooth, shorter than lateral valves. Caudal lamellae ( Figs 3j–k View Figure 3 ) elongated, nine times longer than their widest part, parallel-sided; nodated, divided into two regions: a basal 0.70–0.75 strongly sclerotized, and an apical 0.20–0.25 membranous short, flexible, and foliated apical one with a pale, almost transparent, and entire apex. Epiproct ( Fig. 4h View Figure 4 ) basal 0.70 of dorsal margin with 13–14 strong setae-like spines; basal 0.65 of ventral margin with 19–20 strong setae-like spines, lateral carinae with 14–16 strong spine-like setae. Paraprocts basal 0.70 of dorsal margin with 13 strong setae-like spines, basal 0.75 of ventral margin with 37– 43 strong setae-like spines, lateral carinae with 22–26 strong spines.

Measurements (mm). TL 9.65–9.67; AL 5.71–5.75; PfL 1.00–1.107; MsfL 1.427; HtfL 1.7; CeL 0.21; MgL 0.18; MLh 1.41; MWh 2.3; epiproct length 2.64, maximum width 0.35; paraproct length 2.28, maximum width 0.35. These measurements apply to both males and females, and no significant differences were found.

Differential diagnosis

Psaironeura can be grouped with Neoneura and Protoneura on the basis of their nodated caudal lamellae ( Neiss & Hamada, 2012). However, they can be differentiated by their numbers of labial palp setae, the expression of their lateral projections on the prothorax, and the shape of the apexes of their caudal lamellae ( Table 1) (Román-Herácleo et al., 2021).

Although the known larvae of the remissa and tenuissima species groups of Psaironeura are morphologically similar to those of P. angeloi and P. tenuissima , respectively, it is possible to discern some differences between them ( P. angeloi in parentheses): prementum distal margin strongly pronounced (triangular), reaching half of the labial palp length (slightly pronounced reaching 1/3 of labial palp length); apex of epiproct entire, rounded and without terminal filament (apex trilobate, with a filament on the middle lobe); apex of paraprocts entire, rounded and without filament (apex bilobate, with a filament on the middle lobe); 37–43 (22) spines on the lower margin of paraprocts.

Habitat and Ecology

Psaironeura adults are found in dense forest vegetation, in the lower stratum of the vegetation, and near lateral pools or backwaters ( Fig. 4a View Figure 4 ) ( Mendoza-Penagos et al., 2022). The larvae studied here were collected in Amazon lowland forest black-water streams of the first or second orders, among dead leaves and roots in pools adjacent to the main course of streams. These situations matched the habitat described by Román-Herácleo et al. (2021) for P. angeloi .