Gynacantha rosenbergi KAUP

Theischinger, G., 2007, The final instar larvae of Gynacantha rosenbergi KAUP and Antipodogomphus proselythus (MARTIN) (Odonata, Aeshnidae & Gomphidae), Linzer biologische Beiträge 39 (2), pp. 1233-1237 : 1233-1234

Gynacantha rosenbergi KAUP ( Figs 1, 2 )

FRASER (1963) pointed out that the larva TILLYARD (1916) had described as G.

rosenbergi belonged to G. dobsoni FRASER , a statement agreed to by THEISCHINGER

(2002). The following, therefore, is the first description of the larva of G. rosenbergi .

M a t e r i a l: 1 final instar male exuvia and 1 final instar female exuvia from larvae collected in a pond nr Deep Forest Lodge, Cape Tribulation, Queensland, Australia, 28.12.2006, S. Butler / adults emerged in Sydney, Grays Point, 28./ 29.3.2007, G. & C. Theischinger.

Total length 38.5-39.0 mm; width of head including eyes 8.0 mm; length of metafemur 5.9-6.2 mm; length of abdomen 26.8-27.2 mm. Prementum: length 6.1-6.2 mm; width at distal end 4.4-4.5 mm, at base 1.7-1.8 mm.

D i a g n o s i s Prementum moderately slender, slightly petiolate, length/width ratio 1.38-1.40; ligula margins curved, a tiny tooth each side of, and very close to, median cleft. Labial palps with row of 6-7 long palpal setae and 2-3 short palpal setae; a few additional short setae irregularly spaced next to the short setae at the basis of the row.

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Approximately right angle between angular prothoracic processes, the anterior process slightly forward directed and somewhat narrower than the posterior; notal lobes small, angulated. Distinct lateral spines on abdominal segments 6-9, a tiny indication of a spine on 5. Epiproct almost as long as paraprocts. Male cerci more than 95 %, basal projection less than 40 % length of epiproct. Female gonapophyses reaching to 2/3 length of segment 10; female cerci about 90 % length of paraprocts.

R e m a r k s: Apparently G. rosenbergi is the sister species of G. dobsoni FRASER. Accordingly the larva of G. rosenbergi is very similar to G. dobsoni . Even though the prementum of G. rosenbergi was found stouter (length/width ratio 1.38-1.40) and the number of long palpal setae was found greater (6-7) than is known of G. dobsoni (length/width ratio of prementum>1.50; 5 long palpal setae) it appears that more material is needed to establish if these differences are consistent.

Figures

Figs 1, 2: Gynacantha rosenbergi KAUP, final instar exuviae: (1) male, dorsal; (2) female, ventral.