Oxystigma caerulans De Marmels 1987

Garrison, Rosser W., 2014, Review of Oxystigma Selys with the synonymy of Oxystigma williamsoni Geijskes (Odonata: Heteragrionidae), Zootaxa 3780 (2), pp. 347-364 : 350-358

Oxystigma caerulans De Marmels 1987

Figs. 1 (head), 15–16 (thx), 26 (setifer), 41–42 (app), 58 (map)

Oxystigma caerulans De Marmels, 1987: 233 (description & Figs. holotype ♂, paratype ♂, ♀, larva by supposition,);— De Marmels 1990: 335 (checklist);— Bridges 1994: VII.40 (catalog);— Tsuda 2000: 70 (catalog); — Heckman 2008: 298 (key to species); Garrison et al. 2010: 99 –100 (list, Figs. ♂ app, genital ligula).

Types. Holotype ♂: VENEZUELA, Bolivar State, km 125, road EI Dorado-Santa Elena, de Uairén, 1280 m, 20–22 May 1985, J. De Marmels leg, in MIZA [not examined]

Specimens examined. Total: 4♂, 1♀. VENEZUELA, Bolívar State. km 125, road EI Dorado-Santa Elena, de Uairén (Sierra de Lema) {N 6.73°, W 61.64°}, 1,280 m, 20–22 May 1985, J. De Marmels leg, 1♂, 1♀ (paratypes); stream 2 km N of Salto del Danto, along highway 10; 87x 057 [T.W. Donnelly year/collection number] {N 5.99°, W 61.41°}, 1–2 Aug. 1987, T.W. Donnelly leg. 2♂; "La Escalera vor Waldende a Luepa'; "locality label a bit questionable: type locality probably less than one km before end of forest, heading to Luepa (not 2 or 3 km, as on label [J. De Marmels, pers. comm.]" {N 5.77°, W 61.46°}, 1200 m, 2 Aug. 1987, 1♂ (all RWG).

Diagnosis. Male cercus is unique in possessing a supplementary denticulate ridge at basal 0.30 best seen in medio-dorsal view ( Figs. 41–42 ). These denticles ("dorso-internal submedian hook or tubercle" of De Marmels,1987) vary as to number and condition; they are absent in O. cyanofrons ( Figs. 43 , 49–51 ) and O. petiolatum ( Figs. 44–48 , 52–57 ). A transverse ridge bisects the medial margin of the medial lobe (absent in O. cyanofrons , Figs. 43 , 49–51 and O. petiolatum Figs. 44–48 , 52–57 ) and the distal portion of the cercus beyond the posterior margin of the medial lobe is relatively short compared to that of O. cyanofrons ( Figs. 43 , 49–51 ) and O. petiolatum ( Figs. 44–48 , 52–57 ).

Female is unique by the club-like setifer ( Fig. 26 ) ending more or less at the level of the anteriormost portion of the intersternite; the setifer is longer and surpasses the margin of the intersternite in O. cyanofrons ( Figs. 27–30 ) and O. petiolatum ( Figs. 25, 31–34 ).

Remarks. The morphological characters given here supplement the diagnosis by De Marmels (1987) in his original description. Variation noted in the thoracic pattern mentioned in the original description is illustrated here for the synthorax ( Figs. 15–16 ). The head ( Fig. 1 ) is dark and is similar to many O. petiolatum .

Distribution. This species is thus far known from southern Bolívar State, Venezuela, though it will likely turn up in neighboring Brazil. De Marmels (1987) mentions that "… adults of O. caerulans sp. n. were common along a black ("red") water creek in the forest. It was the only megapodagrionid seen."

Figures

FIGURES 1 – 8. Head, anterior (frontal) view.

FIGURES 41 – 48. Right male cercus, medio-dorsal (internal) view

FIGURES 49 – 57. Right male cercus, dorsal view (A), postero-mesal view (B)

FIGURES 25 – 34. Female intersternite and setifer (mesopresternum), left lateral view.

FIGURES 9 – 16. Head, anterior (frontal) view (continued); 15 – 16. thorax dorsolateral view.