Afrocladus kenyaensis, Nel, Andre, Garrouste, Romain & Prokop, Jakub, 2015

Nel, Andre, Garrouste, Romain & Prokop, Jakub, 2015, The first African Anthracoptilidae (Insecta: Paoliida) near the Permian — Triassic boundary in Kenya, Zootaxa 3925 (1), pp. 145-150 : 147-148

Afrocladus kenyaensis sp. nov.

( Figure 3–4 )

Material. Holotype specimen NHM II 3069 a, b (print and counterprint), Natural History Museum, London, UK.

Etymology. Named after the Kenya country.

Age and outcrop. Late Permian (?), Mombasa Basin, Lower unit of Maji ya Chumvi Formation, Duruma Sandstones series, Karoo supergroup, Kenya.

Diagnosis. Based on hind (?) wing venation only, wing longer than that of Afrocladus pumilio , RP closely parallel to RA near its base, CuA with four anterior branches instead of three in Afrocladus pumilio .

Description. Nearly complete single wing with part of anal area missing, 9.0 mm long, 2.7 mm wide; simple, straight, concave ScP closely parallel to Radius, 0.2 mm apart, ending on costa 3.1 mm from wing base; area between ScP and costal margin narrow, 0.2 mm wide, without visible crossveins or veinlets; radial stem straight, with RP separating from RA 3.2 mm from wing base; RA straight, apparently simple; slightly concave RP with two visible branches; RP closely parallel to RA at its base, touching median vein close to its base; slightly concave median vein divided into two parallel simple branches 2.5 mm from wing base; a brace m-cua between M and CuA 1.8 mm from wing base; CuA and CuP emerging from a common stem; convex CuA anteriorly pectinate with four parallel simple branches less convex than main stem of CuA; concave CuP simple, weakly curved with a rather narrow area between it and CuA, 0.5 mm wide; area between CuP and posterior wing margin ca. 1.1 mm wide; first anal vein convex, simple, weakly curved; second anal vein more poorly preserved but with apparently two posterior branches; two further anal veins more very poorly indicated; several simple crossveins between branches of M and RP; all branches of RP, M and CuA weakly curved and parallel.

Discussion. These two fossils fall in the Anthracoptilidae sensu Guan et al. (in press), as it has the following diagnostic characters of the family, i.e. ScP ending on RA or on costal margin; RP emerging from R in basal half of wing; median vein strongly approximate or shortly fused with RP near base of RP (synapomorphy); branches of RP, median vein and CuA strongly parallel at least in their basal halves; median vein braced to CuA by a short convex cross-vein mp-cua; CuA and CuP emerging from a long common stem; main stem of CuA strongly convex, but anteriorly pectinate with at least a series of parallel branches, all less convex than main stem of CuA (synapomorphy); CuP concave simple; at least two anal veins more convex than CuP; anal area can be very large or not.

The presence of a common stem Cu from which CuA emerges directly excludes affinities with the archaeorthopteran of the clade Cnemidolestodea Handlirsch, 1937 (sensu Béthoux 2005), in which CuA is also anteriorly pectinate (see discussion in Guan et al. in press).

These two wings have a very narrow area between costa and ScP, suggesting they are hindwings, as this area is clearly broader in the forewings of the other Anthracoptilidae .

After Rasnitsyn & Aristov (2004), only the genera Jarmilacladus, Rhinomaloptila, and Spargoptilon share with Afrocladus the ScP ending on costal margin and not on radius. This character seems to be rather variable at generic level because Mesoptilus carpenteri Guan et al., 2015 , shares it while Mesoptilus dolloi (Lameere 1917) has ScP ending on radius.

Afrocladus differs from all anthracoptilids except Paracladus retardatus Carpenter, 1966 , in the distinctly shorter ScP, with apex close to base of RP. Afrocladus pumilio and Afrocladus kenyaensis have also very small wings, 5.5 to 9.0 mm long, unlike the other Anthracoptilidae that have wings ranging between 17 to 48 mm long.

Conculusion The presence of fossil insects on the surface of borehole samples is highly improbable, although few other records are known (viz. the case of the holotype of Permophlebia uralica Nel et al., 2001). These two discoveries in the same outcrop suggest that the corresponding layers are probably very rich in fossil terrestrial arthropods. It would be of great interest to search for new material in situ. Afrocladus pumilio and Afrocladus kenyaensis are the first African and the youngest representatives of the Anthracoptilidae , and of the Paoliida. They are of very small sizes, distinctly smaller than all the other Paoliida except some Blattinopsidae ( Glaphyrophlebia pygmaea (Meunier, 1907) from the Late Carboniferous of France, with a wing 14 mm long) ( Hörnschemeyer & Stapf 2001). This size reduction could be put in parallel to a similar phenomenon that seems to have affected the last representatives of the order Palaeodictyoptera during the Late Permian ( Béthoux et al. 2007). It could be due to adaptations to environmental changes that have taken place around the P-T boundary ( Aristov et al. 2013).

Figures

FIGURE 3. Afrocladus kenyaensis sp. nov., holotype NHM II 3069 a, b, photograph of wing, copyright NHM, London (scale bar represents 1 mm).

FIGURE 4. Afrocladus kenyaensis sp. nov., holotype NHM II 3069 a, b, drawing of wing (scale bar represents 1 mm).