Eutomostethus gagathinus (Klug, 1816)

Macek, Jan, 2014, Descriptions of larvae of the Central European Eutomostethus species (Hymenoptera: Symphyta: Tenthredinidae), Acta Entomologica Musei Nationalis Pragae 54 (2), pp. 685-692 : 690-691

Eutomostethus gagathinus (Klug, 1816)

( Figs 4 , 5 )

Material examined. CZECH REPUBLIC: BOHEMIA BOR.: Krušné hory Mts., PĜebuz (5641), 12.viii.2011, larvae on Carex hirta ; J. Macek lgt. & det. ( NMPC) .

Description of the last instar larva. Body length 12–13 mm. Head amber yellow, granulose with small dark spot in middle of occiput on coronar suture; head in upper half with scattered tiny setae and a row of longer setae alongside epistomal suture; clypeus with six setae, labrum symmetrical, deeply emarginated with eight setae, mandibles with one seta, palpifer with three setae, maxillar palpus with one seta, stipes with one seta; body in upper part grey-yellowish, in lower part paler; dark dorsal longitudinal and underneath white margined supraspiracular strips; cuticle granulose; prothoracal suprapleural lobe protuberant; ¿rst prothoracal annulet with four glandubae; third abdominal segment with six annulets; second and fourth annulets with scattered tiny cylidrical setae; fourth annulet with four glandubae, ¿rst and second postspiracular lobes with one glanduba each, subspiracular and suprapedal lobes with one glanduba and numerouse tiny blackish cylindrical setae; fourth annulet of the ninth abdominal segment with six glandubae, anal segment with numerous scattered glandubae over major part of segment, suranal lobe with four glandubae, posterior margin of suranal and anal lobes densely pubescent.

Notes on identification. Eutomostethus gagathinus differs from the similar larvae of E. punctatus and E. luteiventris in the surface sculpture of the anal segment (see Fig. 4a ).

Bionomics. Habitat: mesophile and humid meadows, marshes, open grasslands and wetlands from planar to montane zone; univoltine; flight period May to August; larval period July to September; host plants: Juncus sp. ( LACOURT 1999), Carex paniculata ( LISTON 2011) , C. hirta (new record). Mature larvae build for hibernation a fragile parchment cocoon covered with soil particles, in which they also pupate in the next spring.

Discussion. LACOURT’ s (1999) mention of Juncus as a food plant is questionable since his information source is not given. LISTON (2011) assumes C. paniculata to be probable larval food plant, due to having observed abundant specimens flying around the stands of this plant. I swept some adults on a humid meadow with abundant stands of C. hirta near the village PĜebuz in Krušné hory Mountains, North Bohemia, Czech Republic. On a subsequent visit to the same place in August I swept several Eutomostethus larvae from Carex hirta which were successfully reared in captivity to adult stage and belong to E. gagathinus .

Figures

Figs 1–4. Mounted larvae from alcohol. 1 – Eutomostethus ephippium (Panzer, 1798); 2 – E. luteiventris (Klug, 1816); 3 – E. punctatus (Konow, 1887); 4 – E. gagathinus (Klug, 1816). Lettering: a – the cuticular sculpture of the anal segement; b – the prothorax, the arrow indicating the protuberant suprapedal lobe. Scale bar: 2 mm.

Figs 5–8. Living last instar larvae (a – lateral view; b – dorsal view). 5 – Eutomostethus gagathinus (Klug, 1816); 6 – E. ephippium (Panzer, 1798); 7 – E. punctatus (Konow, 1887); 8 – E. luteiventris (Klug, 1816). Scale bar: 5 mm.