Partisaniferus edjarzembowskii, HAUG & HAUG, 2022

HAUG, JOACHIM T. & HAUG, CAROLIN, 2022, Another strange holometabolan larva from Kachin amber-the enigma of the beak larva (Neuropteriformia), Palaeoentomology 5 (3), pp. 276-284 : 278-279

? Partisaniferus edjarzembowskii sp. nov.

urn:lsid:zoobank.org:act:46CB5E22-3E9E-4A03-86EB-975D4199E6FD

Holotype. SNHM-6013 (formerly PED 0740 )

Additional material. PED 0596

Etymology. The species is named in honour of Edmund Jarzembowski and his work on fossil insects. When written as? P. edjarzembowskii , the name reads basically as “PED jarzembowskii” in honour of his contributions, especially also on immatures of fossil insects and their study, as a part of PED = Palaeo-EvoDevo.

Diagnosis. Trunk segments with continuous tergites without subdivision in several sclerites. No apparent protrusions on abdomen segments. Trunk end broad, only slightly narrower than preceding trunk, posteriorly rounded.

Differential diagnosis. Differs from Partisaniferus atrickmuelleri in lacking any differentiation into distinct sclerites and abdomen protrusions, and in the shape of the trunk end, which is narrow trapezoid in dorsal view.

Locality and horizon. Kachin, Myanmar, earliest Cenomanian.

Description. General. Very small holometabolan larva ( Figs 1A–D , 2A ). Body organised into head and trunk. Head composed of six segments (inferred, see discussion). Anterior trunk (thorax) with three longer segments (pro-, meso-, metathorax), ventrally each carrying a pair of locomotory appendages (legs). Posterior trunk (abdomen) with nine units, anterior eight representing true segments, last unit, trunk end, likely a compound structure of several segments. All trunk units with prominent dorsal sclerites (tergites). Each trunk segment with convex lateral rims, with a pair of setae one on each side, trunk end with two pairs of setae.

Head. Triangular in dorsal view.Anteriorly drawn out into beak-like protrusion ( Fig. 1C ), most likely formed by some components of mouthparts, but unclear by which ones. No clear structures of ocular segment visible, no eye structures apparent, clypeo-labrum complex (possible appendage derivative) possibly contributing to beak; faint V-shaped line on beak, possibly as edge of clypeolabrum.

Antennae [antennulae] inserting far lateral on head, with four visible elements ( Fig. 1C, D ). Proximal element proximally very wide, strongly tapering distally to about 50% of proximal width; length about as long as distal width. Element 2 of similar length, also tapering distally to about 50% of the proximal width. Element 3 tubular, slightly narrower than distal width of element two, slightly longer than wide. Element 4 slightly shorter, but about as wide as element 3, distally rounded.

A single pair of palps apparent ( Fig. 1C, D ), unclear if maxillary [maxillulary] or labial [maxillary] palps, with two elements. Proximal element conical, nearly twice as long as proximal width. Distal width only half of proximal width. Distal part narrow, elongate, spine-like.

Anterior trunk (thorax). Trunk segment 1 (prothorax) largest, slightly wider than posterior width of head, nearly twice as long as head capsule without beak ( Fig. 1A, C ). Ventrally with a pair of locomotory appendages (legs), no details discernible.

Trunk segment 2 (mesothorax) slightly shorter than prothorax, similar in width ( Fig. 1A, C ). Ventrally with a pair of locomotory appendages (legs), no details discernible.

Trunk segment 3 (metathorax) similar in size to mesothorax ( Fig. 1A, C ). Ventrally with a pair of locomotory appendages (legs), no details discernible.

Posterior trunk (abdomen). Trunk segment 4 (abdomen segment 1) slightly shorter than metathorax, similar in width.Trunk segments 5–10 (abdomen segments 2–7) similar to trunk segment 4. Trunk segment 11 (abdomen segment 8) about as long, but slightly narrower than preceding segments. Trunk end anteriorly narrower than trunk segments and slightly shorter, posteriorly rounded ( Fig. 1A–D ).

Figures

FIGURE 1.?Partisaniferus edjarzembowskii sp. nov., beak larva, SNHM-6013, Kachin amber, Myanmar, in dorsal view under different light settings.A, Under unpolarised ringlight with black background.B, Under cross-polarised light with blackbackground. C, Colour-marked version of B. D, Under transmitted light. Abbreviations: a2–a8 = abdomen segments 2–8; at = antenna; bk = beak; hc = head capsule; mt = metathorax; pl = palp; pt = prothorax; te = trunk end.

FIGURE 2. Comparison of drawings of the different beak larvae and other larvae to illustrate possible ontogenetic changes. A,?Partisaniferus edjarzembowskii sp. nov., beak larva 3, SNHM-6013; scale bar on the lower right. B–D, All known beak larvae at the same scale; note that the larva in B has a much larger body size than those in C and D; scale bar between B and D applies to B–D. B, Possible second specimen of?Partisaniferus edjarzembowskii sp. nov., beak larva 2, based on Haug et al. (2022b). C,?Partisaniferus edjarzembowskii sp. nov., beak larva 3, based on this study. D, Partisaniferus atrickmuelleri, beak larva 1, based on Haug et al. (2020e). E. Enlarged version of D; scale bar on the lower right. F and G, Comparison of first and last larval stage of a representative of Nevrorthidae at the same scale; scale bar under G applies to F and G. F, Last larval stage of Nevrorthus sp. based on Gepp (1984). G. First larval stage based on Haug et al. (2019b). H and I, Comparison of first and last larval stage of a representative of Psychopsidae (Psychopsis elegans) at the same scale based on Tillyard (1918); size provided by magnification factor, hence no scale bar provided. H, Last larval stage. I, First larval stage.