Tumidistephanus prometheus Ge and Tan, 2023

Ge, Si-Xun, Jiang, Zhuo-Heng, Ren, Li-Li, van Achterberg, Cornelis & Tan, Jiang-Li, 2023, New insights into the phylogeny of Stephanidae (Hymenoptera: Apocrita), with a revision of the fossil species, Arthropod Systematics & amp; Phylogeny 81, pp. 819-844 : 819

† Tumidistephanus prometheus Ge and Tan sp. nov.

Figures 8 , 9 , 10

Holotype. ♀;

BFU, Myanmar Amber, Cretaceous. Part of Si-Xun Ge’s collection.

Etymology.

The species’ name is derived from the name Prometheus in ancient Greek mythology, who brought fire and knowledge to humans. We named the new species analogous to its discovery, bringing a new perspective on Stephanidae systematics.

Diagnosis.

See generic diagnosis above.

Description.

Female. Total body length (from head anterior to metasoma distal margin, without ovipositor sheath) 2.8 mm; forewing length 2.2 mm; Ovipositor sheath 1.05 mm. - Head: Antenna elongate, filiform with at least 19 flagellomeres; the first flagellomere robust and elongated, and second flagellomere relatively short; Head elliptical with compound eyes sub-triangular; vertex with five tubercles; temple distinctly narrowed behind eye; Maxillary palpus 5-segmented, elbowed between MP II (maxillary palpomere II) and MP III (maxillary palpomere III) with its basal two segments relatively short and robust, while apical three segments long and slender. - Mesosoma: Pronotum robust with U-shaped pronotal fold strongly developed; middle part of pronotum protuberant weakly differentiated from posterior part and at somewhat higher level. - Wings: Forewing with vein 1-M distinctly curved, 1.7 × as long as vein 1-Rs and 2.1 × vein 1m-cu; vein A incomplete, only reach 1cu-a; vein 2-Rs 2.9 × as long as vein r-rs; vein r-rs ends middle part of pterostigma behind the level of apex of pterostigma; vein Rs + M and 1Cu non-parallel; vein 1Cu with spiny setae basally. vein 2Rs+M extremely elongated, 0.4 × as long as vein 2-Rs and 1.05 × as long as 1-Rs, the origin of veins 2-Rs and apical abscissa of vein M non-connected; vein 2Cua nebulous apically with 2Cub completely absent. - Legs: Fore and mid legs with their femur and tibia flattened and expanded. Hind coxa rather robust, mostly shiny with distinct lateral groove; hind femur coriaceous, extremely robust with its median part distinct swollen as nearly oval shaped. Hind femur dentigerous, with 2 large teeth and 10 medium sized teeth (4 of them between large teeth and 6 behind the apical large teeth); hind tibia elongate and 1.2 × longer than hind femur, with its basal narrow part 1.1 × as long as apical widened part (apical widened part rather extended with its maximum width 5.0 × as wide as minimum width of basal narrow part), inner side of widened part basally with two shallowly concave; hind tarsus with five tarsomeres; basitarsus 5.8 × as long as wide. - Metasoma: Metasoma with eight segments. First tergum and sternum not fused laterally, Tergite I rather slender, 1.2 × as long as tergite II. Pygidial impression reverse V-shaped. Ovipositor sheath 0.76 × as long as metasoma. Ovipositor tip laterally compressed, apical without distinct teeth.

Remarks.

This new species exhibits distinctive morphological features, such as the flattened and expanded femur and tibia of the fore and mid legs. This feature suggests that the subgenual organ of Stephanidae likely developed during the Cretaceous. Additionally, the new species has a flattened and elliptical head, which is rarely found in extant species but reminiscent of the head shape of Lagenostephanus . A similar counterpart to its extremely swollen tibia can be found in the extant genus Madegafoenus ; however, the swollen and multituberculate hind femur may be considered an autapomorphy. Combining these characteristics along with the results of the phylogenetic analysis, we assigned the new species and genus to the subfamily Lagenostephaninae Ge and Tan, subf. nov.

Figures

Figure 8. Tumidistephanus prometheus Ge and Tan, sp. nov. Holotype ♀. A Head, frontal view. B Wings. C Tergite I and II, lateral view. D Ovipositor and ovipositor sheath. E Hind leg.

Figure 9. Details of Tumidistephanus prometheus Ge and Tan, sp. nov. Holotype ♀. A Head, frontal view. B Wings. C Hind leg. D Metasoma.

Figure 10. Habitus of Holotype ♀. Tumidistephanus prometheus Ge and Tan, sp. nov. A Photo of specimen. B Line drawing of habitus.