Nesocordulia fossa Bernard, Daraż, Ravelomanana & Dijkstra, 2025

Bernard, Rafał, Daraż, Bogusław, Ravelomanana, Andrianjaka & Dijkstra, Klaas-Douwe B., 2025, Six new species of Nesocordulia McLachlan, 1882 reveal an insular evolutionary radiation of dragonflies on Madagascar (Odonata: Anisoptera: Libelluloidea), Zootaxa 5660 (2), pp. 151-193 : 160-161

publication ID	https://doi.org/10.11646/zootaxa.5660.2.1
publication LSID	lsid:zoobank.org:pub:103B00A2-9573-45C1-B1AE-A1FA9772E247
DOI	https://doi.org/10.5281/zenodo.16602828
persistent identifier	https://treatment.plazi.org/id/B042BE13-FF91-AA7E-71DD-53DBFD19FE8A
treatment provided by	Plazi
scientific name	Nesocordulia fossa Bernard, Daraż, Ravelomanana & Dijkstra
status	sp. nov.

Treatment

Nesocordulia fossa Bernard, Daraż, Ravelomanana & Dijkstra sp. nov. —Fossa Knifetail

Figs 4 View FIGURE 4 , 15–19 View FIGURE 15 View FIGURE 16 View FIGURE 17 View FIGURE 18 View FIGURE 19

http://zoobank.org/ urn:lsid:zoobank.org:act:C2B3AC67-AEB0-482B-AD98-99339259908B

Etymology. The name, a noun in apposition, refers to Madagascar’s largest carnivore, the similarly rufous, longbodied and enigmatic Fossa ( Cryptoprocta ferox Bennett, 1835 ).

Type material. Holotype male ( RMNH.INS.1552538), Tsakoka trail, 18.7943° S, 48.4267° E, 950 m asl (coordinates approximate), Mantadia National Park, Alaotra-Mangoro Region, Madagascar, 17.01.2016, leg. K.- D.B. Dijkstra and A. Ravelomanana. GoogleMaps

Diagnosis. Comparatively large species, easily separated from all congeners except N. rubricauda by the reddish brown body, dark brown wing bases, and denser venation, especially between the cubital and anal veins. Aside from unique features, such as the shape of the cerci and hamule (see Figs 15–16 View FIGURE 15 View FIGURE 16 and 17–18 View FIGURE 17 View FIGURE 18 , respectively), yellow markings on the largely reddish brown thorax, and black apical smudges laterally on the reddish brown S3–6, differs from N. rubricauda by the yellow marking on the clypeus and the single cell rows subtended by Rspl.

Description. Holotype male. Total length 56.6, abdomen (excluding appendages) 39.4, Fw 41.7, Hw 40.6, Fw Pt 2.4, cerci 2.7. Fw Ax 15–16, Fw Px 12, Hw Ax 9, Hw Px 14. Colouration generally reddish brown, with metallic green, yellow and black markings ( Fig. 4a View FIGURE 4 ).

Head. Face dark in various shades of brown with a yellow triangular centre ( Fig. 4e View FIGURE 4 ). Postfrons and frons sides olive brown with metallic sheen locally. Frontal shield of antefrons blackish brown with trace of metallic blue; the lower edge of antefrons olive brown with a minute yellow spot in the middle. Anteclypeus and central postclypeus yellow, sides of postclypeus olive brown. Labrum dark reddish brown with a paler amber brown centre ( Fig. 4e View FIGURE 4 ). Labium pinkish brown with yellowish admixture at the base ( Fig. 4b View FIGURE 4 ). Occipital triangle reddish- to dark brown. Postgenae yellowish to reddish brown ( Fig. 4b View FIGURE 4 ). Eyes in live purplish brown anterodorsally and light blue posteroventrally ( Fig. 4a View FIGURE 4 ).

Thorax. Synthorax reddish brown with three evenly distributed metallic stripes (green with blue reflections) on mesepisternum, mesepimeron and metepisternum, and with adjacent two yellow spots ( Figs 4a,b View FIGURE 4 , 19 View FIGURE 19 ). The mesepimeral yellow spot shorter and together with irregular purplish brown patch situated on the lower extension of the metallic stripe while the metepimeral yellow spot long and extending behind the metallic stripe. Legs dark brown to black with basal parts (coxae, trochanters and parts of femora, the longest on forelegs) ochre to reddish brown ( Figs 4a,b View FIGURE 4 ).

Wings. Dark brown bases, larger in Fw, reaching farthest in costal and subcostal space (crossing Ax 2 in Fw and Ax 1 in Hw) and closest in cubital space ( Figs 4a,b View FIGURE 4 ). Wing membrane also slightly tinted with brownish locally, especially in its anterior and distal parts ( Fig. 4f View FIGURE 4 ). Pt medium-sized, black, but magnified, with a paler dark brown border along veins. Venation in Hw: (a) row between the cubital and anal veins with 5–8 cells doubled; (b) row between R4 and the median vein with 8–9 cells doubled (even tripled distally) ( Fig. 4f View FIGURE 4 ). Rspl subtending single row of cells. Membranula whitish.

Abdomen. Reddish brown, most intensively on S8–9, with black rings of posterior field of tergites (beginning from S2). S3–6 each with a posterolateral triangular black smudge bordering the posterior black rings ( Figs 4a,d View FIGURE 4 ). No yellow pattern, only ochre yellow brush on S3–7 anterolaterally.

Secondary genitalia. Branches of the hamule separated by a deep and wide gap, with the posterior branch pressed against the genital lobe and the anterior branch tapered distally into a triangular and unbent tip ( Figs 4b View FIGURE 4 , 15 View FIGURE 15 ). In ventral view, the inner lobe of the anterior branch bluntly triangular and elongated along the main axis of the body ( Fig. 16f View FIGURE 16 ). Genital lobe relatively long, bluntly triangular, directed downwards and slightly posteriorly, pinkish brown with rusty ochre hair-like setae ( Figs 4b View FIGURE 4 , 15 View FIGURE 15 ).

Caudal appendages. Cerci medium-length, reddish brown (as the abdomen), basally darker. In dorsal view, with arched base and out-curved tapered tips, thus appearing sinusoidal or lyre-shaped ( Figs 4c View FIGURE 4 , 18 View FIGURE 18 ). In lateral view, gently arched up (with the bent near half of their length), not distended in their distal half, and with an undercut tip ( Fig. 17 View FIGURE 17 ). Epiproct reddish brown and long, reaching 90% of the cerci length ( Figs 4c View FIGURE 4 , 17 View FIGURE 17 ).

Female. Unknown.

Distribution and ecology. Known only from the type locality in central-eastern Madagascar ( Fig. 21 View FIGURE 21 ), in the ecoregion of Madagascar Humid Forests ( One Earth 2024) and the hydrographic ecoregion of Eastern Highlands ( Sparks & Stiassny 2022). The male was flying in the middle of the day, but in deep shade, cruising very low over a stream under thick tangles and a closed canopy.