Argia mollis Hagen in Selys, 1865

Cezário, Rodrigo Roucourt, Vilela, Diogo Silva & Guillermo-Ferreira, Rhainer, 2018, Final instar larvae of Argia mollis Hagen in Selys, 1865 and Argia smithiana Calvert, 1909 (Odonata: Coenagrionidae) from the Brazilian Cerrado, Zootaxa 4514 (1), pp. 137-144 : 138-140

Description of the final instar larvae of Argia mollis Hagen in Selys, 1865

Figs. 1–6 .

Material examined. 1 ♂ F0 exuvia ( Fig. 1a ): BRAZIL, Chapada dos Guimarães, Riacho 1 Ponte (15°31’93.06” S, 55°95’23.89” W), 21-x-2015, Guillermo-Ferreira leg. , 1♂ (reared in laboratory).

Head. Almost rectangular, wider than longer, cephalic lobes large and bulging, bearing small setae. Posterior border widely concave ( Fig. 1b ). Medial margin of compound eyes slightly straight. Ventral margin of the eyes at mandibles level. Antennae 7-jointed, longer than the head, third antennomere being the longest, antennomere 1 brownish, yellowish to pale on 4–7; length of antennomeres: 0.10, 0.37, 0.53, 0.41, 0.26, 0.15, 0.07 ( Fig. 2 ). Prementum ( Fig. 3 ) about 0.74 as wide as long, bare dorsal surface, distal margin moderately prominent, its apical margin finely serrulated ( Fig. 3a ); labial palp with two teeth, both smaller than movable hook, the medial (outer) the longest; outer margin of the hook finely crenulated ( Fig. 3b ); 1 short palpal setae on the base of movable hook ( Fig. 3b ). Mandibles present molar teeth but no molar crest, with the following formula: L 1+2345 0 a b (1>3>2>4>5), R 1+2345 0 a (1>3>2>4>5) ( Fig. 4 ). Pronotum dark brown, quadrangular, bearing small setae. Wing pads brown, extending up to segment 4. Legs light brown with two dark lateral spots on femora and tibiae ( Fig. 1a ). Abdomen. Larvae dark brown, with pale dorsolateral spots on S1–3, and darker markings on S4–8 basal ring ( Fig. 1a ). Male cerci ( Fig. 5 a–b) enlarged, with small excavations in mediodorsal view ( Fig. 5a ); in lateral view roundly pointed, small concave dorsal excavation, pointed forwards ( Fig. 5b ). Male gonapophysis pyramidal blunt, dark; surpassing 30% of S10 ( Fig. 5 c–d). Caudal lamellae (Attention: some portions of both lamellae are folded on itself and highlighted with red arrows. The descriptions represent the structures without the folds) laminar, oblong, narrow foliated at the base, foliaceous at the middle; both lateral and median lamellae with ochre coloration; both median and lateral lamella with irregular pale spots on the mid portion; median lamella shorter than lateral lamellae ( Fig. 6 a–b).

Measurements (n = 1). Total length without appendages: 11.99. Total length of head: 1.55; max. width: 3.28. Prementum length: 2.90; max. width: 2.16. Total length of labial palp: 1.58; max. width: 0.36. Femur I: 2.05; II: 2.64; III: 3.74. Tibiae I: 2.37; II: 2.79; III: 3.37. Inner wing pads: 4.45; external wing pads: 4.23. Medial caudal lamellae: 4.35; lateral caudal lamellae: 4.57.

Habitats: The larvae of A. mollis was collected in a small order rocky stream, among the roots of a small patch of aquatic vegetation.

Differential diagnosis. Provided under diagnosis of A. smithiana below.

Figures

FIGURE 5a–d. Argia mollis. 5a. mediodorsal view of F0 exuvia cerci, 5b. lateral view of right cercus, 5c. lateral view of F0 exuvia S9 and S10, 5d. ventral view of F0 exuvia gonapophyses.

FIGURE 6. Argia mollis. Median and lateral lamellae of F0 exuvia. Red arrows represents folds on some marginal parts of the lamellae.

FIGURES 1–4. Argia mollis. 1a. F0 exuvia habitus, 1b. detail of cephalic lobe; 2. antenna; 3. prementum: 3a. detail of distal margin ligula, 3b. mediodorsal view of labial palp, 3c. lateral detail of setae; 4. right and left mandibles.