Hemerobiidae

Makarkin, Vladimir N., Wedmann, Sonja & Weiterschan, Thomas, 2012, First record of a fossil larva of Hemerobiidae (Neuroptera) from Baltic amber, Zootaxa 3417, pp. 53-63 : 54-56

Hemerobiidae indet., larva

Figs. 1 , 2

Description. Larva approximately 3.6 mm long (including mouthparts), rather swollen.

Head somewhat retracted into prothorax. Head capsule about 0.36 mm long, about 0.36 mm wide; area between antennae and basal parts of mouthparts not clearly visible. Mandibles, maxillae form sucking mouthparts (their parts hard to distinguish from each other); mouthparts slightly shorter than head capsule width, smoothly curved inward; maxillae apparently slightly longer than mandibles with apex somewhat blunt. Antennae slightly longer than head capsule width, distinctly three-segmented; basal segment short, rounded, with smooth surface; second segment approximately twice as long, conspicuously stouter than third segment, both with annulated surfaces; apex of antenna with short bristle. Labial palps three-segmented, slightly shorter than mandible length; two basal segments cylindrical, both slightly longer than wide; terminal segment fusiform, length approximately equal to length of two basal segments together. Dorsal ecdysial lines distinct, Y-shaped. Each eye with four stemmata.

Cervix short, transverse, forming collar which slightly overlaps posterior margin of head capsule. Anterior subsegment of prothorax broad, about 0.6–0.7 mm wide and about 0.3–0.4 mm long; lateral dorsal sclerites large, crescent-shaped. Posterior subsegment of prothorax, meso-, metathorax poorly visible, no measurements can be given.

Legs relatively short, stout, robust. Coxa elongate, stout; trochanter indistinctly visible, apparently elongate; femur rather short, stout; tibia short, only slightly longer than tarsus; claws rather short; empodium between claws short, pad-shaped ( Fig. 2 D).

Abdomen poorly preserved, in general swollen.

Remarks. Some details of the larva are indistinctly visible. The maxillae and their association with the mandibles might be slightly different in the drawing and photo as there are reflecting fractures that disturb the view. The abdomen is obscured by a milky covering and the boundaries between the segments are not clearly visible.

The presence of a short, pad-shaped empodium clearly shows that this is a 2nd or 3rd instar larva; the empodium is long and trumpet-shaped in the first instar larva of Hemerobiidae . Most probably this is a 2nd instar larva, judged from its relatively small size. Such small 3rd instar larvae are unknown in any species of extant Hemerobiidae . For instance, in Sympherobius amiculus ( Fitch, 1855) the 2nd instar larva is 2.81 mm long, and the 3rd instar larva is 4.8 mm long ( Smith 1923); in Psectra diptera ( Burmeister, 1839) the 2nd instar larva is 3.75 mm long, and the 3rd instar (full-grown) larva is 5.5 mm long ( Killington 1946); in Megalomus fidelis ( Banks, 1897) the mature 2nd instar larva is 3.32 ± 0.43 mm long, and the mature 3rd instar larva is 4.53 ± 1.05 mm ( MacLeod 1961).

Figures

FIGURE 1. Hemerobiidae indet., larva, specimen 1530 from coll. T. Weiterschan. A, whole larva, lateral view. B, head and thorax, lateral view. C, head, fronto-dorsal view. All scale bars = 0.5 mm.

FIGURE 2. Hemerobiidae indet., larva, specimen 1530 from coll. T. Weiterschan. A, whole larva as preserved, lateral view. B, head and prothorax, dorsal view. C, mouthparts, ventro-lateral view. D, apex of right mid-leg. dsc, dorsal sclerite; em, empodium; lp, labial palps; md, mandible; mx, maxillae; ti, tibia; tr, tarsus. All scale bars = 0.5 mm (D not to scale).