Cretolixon alatum Lohrmann, 2020

Lohrmann, Volker, Zhang, Qi, Michalik, Peter, Blaschke, Jeremy, Müller, Patrick & Jeanneau, Laurent, 2020, † Cretolixon - a remarkable new genus of rhopalosomatid wasps (Hymenoptera: Vespoidea: Rhopalosomatidae) from chemically tested, mid-Cretaceous Burmese (Kachin) amber supports the monophyly of Rhopalosomatinae, Fossil Record 23 (2), pp. 215-236 : 225-226

Cretolixon alatum Lohrmann sp. nov.

LSID (species): urn:lsid:zoobank.org:act:D47E97C1-EC99-4872-A4BD-314B5496CF2B

(registered on 5 December 2019)

( Figs. 4–8 )

Material

Holotype. Male ( Fig. 4 ), MB.I 6500, deposited in the amber collection of the Museum für Naturkunde Berlin, Berlin, Germany (ex coll. Jens-Wilhelm Janzen), mid-Cretaceous (Albian – Cenomanian) amber from northern Myanmar, Kachin State, Hukawng Valley , Noije Bum Hill, SW of Tanai. The specimen is completely preserved without any significant distortions. The following syninclusions have been observed: one Collembola, Capnodiales, and stellate hairs.

Paratypes. Female ( Fig. 5 ), VL-Bu-04, deposited in the Übersee-Museum Bremen, Bremen, Germany (ex coll. Volker Lohrmann), mid-Cretaceous (Albian–Cenomanian) amber from northern Myanmar, Kachin State, Hukawng Valley. The specimen is almost completely preserved without any significant distortions. The left side of the mesosoma and base of the wings is hidden under an air bubble. Tarsomeres II –V of the right hind leg are missing. In order to access crucial characters of the fossil the amber piece has been cut into two fragments. The following syninclusions have been observed: one Coleoptera ( Staphylinidae ), one Cicada (nymph), one Blattodea (nymph), plant fibers, and stellate hairs.

Female ( Fig. 6b, e ), NIGP173865, deposited in the amber collection of the Nanjing Institute of Geology and Palaeontology, Nanjing, China, mid-Cretaceous (Albian– Cenomanian) amber from northern Myanmar, Kachin State, Hukawng Valley. The specimen is incompletely preserved but without any significant distortions. The posterior half of the second metasomal segment and remainder of the metasoma, as well as apical sections of fore wings and hind wings, are missing. Additionally, a fracture is hiding large parts of the anterodorsal mesosoma.

Male ( Fig. 6a, c, d ), SNSB-BSPG 2020 XCIII 25, deposited in the Staatliche Naturwissenschaftliche Sammlungen Bayerns, Munich , Germany (ex coll. Patrick Müller, BUB 3227), mid-Cretaceous ( Albian–Cenomanian ) amber from northern Myanmar, Kachin State, Hukawng Valley . The specimen is almost completely preserved without any significant distortions. The following parts of the legs are missing: tarsomeres II –V of right fore leg, apical half of tarsomere II and tarsomeres III–V of left middle and right hind legs, and tarsus and tibial spurs of left hind leg. Additionally, several air bubbles hide parts of the left lower mesosoma and parts of the wing. The following syninclusions have been observed: parts of a filiform antenna and leg of an unidentified insect, stellate hairs, and plant fibers .

Diagnosis

As for the genus (vide supra).

Description

As for the genus, with the following additions (n.m. = not measurable, due to preservation).

Male (given for the holotype (MB.I 6500) first followed by the measurements of the paratype (SNSB-BSPG 2020 XCIII 25) in parentheses). Total body length (head plus mesosoma plus metasoma) in lateral view 3.69 mm (4.00 mm; head measured at slightly oblique angle). Head width (in dorsal view) 0.54 mm (0.63 mm; in ventral view). Antennal length 1.79 mm (1.83 mm) (flagellar length 1.56 mm (1.58 mm )). Mesosomal length in lateral view 1.16 mm (1.23 mm). Fore wing length 2.36 mm (2.42 mm). Hind wing length 1.79 mm (1.75 mm). Fore leg lengths: coxa 0.24 mm (n.m.); trochanter 0.15 mm (n.m.); femur 0.55 mm (0.55 mm); tibia 0.35 mm (n.m.); tarsus 0.78 mm (n.m.). Middle leg lengths: coxa 0.24 mm (0.25 mm); trochanter 0.15 mm (0.175 mm); femur 0.58 mm (0.63 mm); tibia 0.53 mm (0.58); tarsus 0.97 mm (0.85 mm; measured at oblique angle). Hind leg lengths: coxa 0.36 mm (n.m.); trochanter 0.15 mm (0.15 mm); femur: 0.72 mm (0.75 mm); tibia 0.78 mm (0.78 mm); tarsus 1.36 mm (n.m.). Metasomal length in lateral view (slightly expanded in holotype) 2.28 mm (2.40 mm).

Female (due to preservation only given for VL-Bu-04). Total body length (head plus mesosoma plus metasoma) in lateral view 5.16 mm. Head width in dorsal view 0.68 mm. Antennal length 2.2 mm (flagellar length 1.9 mm). Mesosomal length in lateral view 1.48 mm. Fore wing length 2.6 mm. Hind wing length 2.00 mm. Fore leg lengths: coxa 0.3 mm, trochanter 0.15 mm, femur 0.55 mm, tibia 0.56 mm, tarsus 1.13 mm. Middle leg lengths: coxa 0.25 mm, trochanter 0.13 mm, femur 0.8 mm, tibia 0.73 mm, tarsus 1.3 mm. Hind leg lengths: coxa 0.38 mm, trochanter 0.23 mm, femur 0.95 mm, tibia 0.93 mm, tarsus 1.68 mm. Metasomal length in lateral view 3.15 mm.

Etymology

The specific epithet alatum (ala (L.) = wing) refers to the presence of fully developed wings.

Figures

Figure 4. Cretolixon alatum gen. et sp. nov., male, holotype (MB.I 6500; ZMB). (a) Habitus in lateral view. (b) Head in slightly oblique frontal view.(c) Mesosoma in lateral view.(d) Partial right antenna.(e) Wings.Abbreviations:ab – apical bristle; FI, FII, FIII – flagellomere 1, flagellomere 2, flagellomere 3; lo – lateral ocellus; oc – occipital carina; p – pedicel; sc – scape. The arrowheads indicate the apical bristles on third maxillary palpomeres (c) and basal flagellomeres (d).

Figure 5. Cretolixon alatum gen. et sp. nov., female, paratype (VL-Bu-04, UMB). (a) Habitus in lateral view. (b) Head and basal halves of antennae in oblique lateral view. (c) Mesosoma in lateral view. (d) Right protibia and protarsus. (e) Wings. The arrowheads indicate the apical bristles on second labial and third maxillary palpomeres (b).

Figure 6. Cretolixon alatum gen. et sp. nov., male and female, paratypes (male: SNSB-BSPG 2020 XCIII 25, SNSB; female: NIGP173865, NIGP). (a, c, d) Male. (a) Habitus in lateral view. (c) Base of right antenna. (d) Base of left antenna. (b, e) Female. (b) Habitus in slightly oblique dorsal view. (e) Partial right antenna (apex of FI to base of FIV). The arrowheads indicate the apical bristles on basal flagellomeres.

Figure 7. Cretolixon alatum gen. et sp. nov., male, holotype (MB.I 6500; ZMB). Venation of fore and hind wings (microtrichia omitted, drawing based on a photograph with a perspective similar to that of Fig. 4e).

Figure 8. Cretolixon alatum gen. et sp. nov., female, paratype (VL-Bu-04; UMB). (a) Basal half of left antenna. (b) Details of mouth parts (maxillary palpus highlighted in grey). (c) Details of mouth parts (labial palpus highlighted in grey). Abbreviations: FI, FII, FIII – flagellomere 1, flagellomere 2, flagellomere 3; G – gena; lp1,..., lp4 – labial palpomere 1,..., labial palpomere 4; M – mandible; mp2,..., mp6 – maxillary palpomere 2,..., maxillary palpomere 6; p – pedicel; sc – scape. Drawings based on Fig. 5b.