Peristicta forceps Hagen in Selys, 1860

Schröder, Noelia M., Anjos-Santos, Danielle, Rippel, Camila G. & Pessacq, Pablo, 2020, Description of the last instar larva of Peristicta aeneoviridis Calvert, 1909 (Odonata: Coenagrionidae), Zootaxa 4728 (4), pp. 461-468 : 465

Peristicta forceps Hagen in Selys, 1860

( Fig. 3 )

Peristicta forceps Hagen in Selys (1860) : male description; Kennedy (1919): holotype genital ligula drawings; Munz (1919): wing drawing, genus included in Zygoptera key; Lencioni (2005): reproduction of Kennedy’s holotype genital ligula drawings; Pessacq (2007), female and larva description, male redescription, thorax, genital ligula and cercus figures, distributional map; Anjos-Santos & Pessacq (2013): genital ligula figures, included in key.

Peristicta aeneoviridis Ris (1913) [nec Calvert, 1909]: female description? record for Misiones Province, Argentina.

Additions to the original larval description:

Specimens examined. Four exuviae (2 ♂♂, 2 ♀♀ laboratory emerged), five F-0 larvae (4 ♂♂, 1 ♀). AR- GENTINA: Corrientes Province, Payubre chico stream and provincial route 29, about 25 km from Mercedes city (-29,02806, -58,17444, 66 m asl), 09-10 x 2003, P. Pessacq & J. Muzón leg.

Head. Similar to P. aeneoviridis , except lacinia ventral teeth proportions as follows: 1:0.5:0.3. Lacinia dorsal teeth followed by three long, thick spine-like setae followed by thin, shorter plumose setae; ventral teeth followed by a row of long, thick or thin, plumose setae.

Thorax. Similar to P. aeneoviridis , except: femora with one wide medial dark band; prothoracic femora ( Figs. 3a, b ) with an irregular row of ovoid and spine-like setae on flexor and extensor margins, remaining surface with scattered ovoid setae; meso- and metathoracic femora flexor and extensor margins with a row of spine-like setae, remaining surface with scattered ovoid setae. Tibia with apical flexor third with plumose setae thicker than in P. aeneoviridis .

Abdomen: Morphological variation of caudal lamellae is addressed in Figures 3 c–h. As described by Pessacq (2007), apex of caudal lamellae is straight or more commonly presents a concavity.

Comments: In the larval description of this species (Pessacq 2007), the coloration pattern of legs and abdomen, as well as leg setae were not described, even though the first characters were shown in the habitus figure. Abdominal coloration is the same as in P. aeneoviridis . The coloration pattern of the caudal lamella is faded in the pictures herein included for P. forceps due to the time preserved in ethanol (more than 15 years), but it can be seen in the figures of Pessacq (2007).

Diagnosis. Peristicta aeneoviridis can be distinguished from P. forceps (characteristics of the latter in parentheses) by having two medial dark bands in femur (one), caudal lamella apex rounded (straight to deeply concave), only ovoid setae on the femur (ovoid and spine-like), small relative size of lacinia ventral hooks (larger) and sparse apical ring of spine-like setae on S6 (denser). Based on the description of Santos (1971), Peristicta guarellae can be distinguished from the other two larvae by the lack of light marginal marks on caudal lamellae and a light longitudinal medial band on the abdomen (dark in remaining species).

Figures

FIGURE 3. Last instar-lava of Peristicta forceps: a) prothoracic femur details, ventral view; b) setae on prothoracic femur, ventral view; c, d, e) median caudal lamella morphological variation, left lateral view; f, g, h) lateral caudal lamella morphological variation, left lateral view.