Xenos gadagkari, Sen and Nain, 2024

Nain, Deepak, Rana, Anjali, Raychoudhury, Rhitoban & Sen, Ruchira, 2024, Morphology, biology and phylogeny of Xenos gadagkari sp. nov. (Strepsiptera: Xenidae): an endoparasite of Polistes wattii (Hymenoptera: Vespidae), Zootaxa 5493 (5), pp. 561-576 : 571-573

Xenos gadagkari, Sen and Nain sp.nov.

Phylogenetic analysis

The phylogenetic analysis of X. gadagkari was conducted with several partial fragments of the mitochondrial COI gene sequences of other species obtained from NCBI. X. gadagkari forms a clade with X. vesparum among several other strepsipterans from different Polistine wasps ( Fig 17 ). The clade is also supported by high posterior probabilities (100) indicating strong reliability of the clade. The X. gadagkari sequences show a synonymous site divergence of 79% (with 68% divergence across all the sites considered) from X. vesparum .

Differences with X. hebraei and X. vesparum

X. gadagkari is phylogenetically closest to X. vesparum (according to currently available sequences). However, X gadagkari is morphologically different from X. vesparum particularly due to the drastic difference in colouration. In the female cephalotheca, the mandibles of X. gadagkari are positioned in a depression larger than their length, while in X. vesparum the depression around the mandibles is smaller than the length of the mandibles. Also, the lower margin below the semicircular field possible of labral region (SES) is elevated ( Fig 15c ) in X. gadagkari , while it is smooth in X. vesparum ( Fig 2D in Richter et al. 2017).

As the description of the adult male X. hebraei is unavailable, it is not possible to compare them. However, according to the description of the female cephalothorax of X. hebraei ( Kinzelbach 1978) ‘the clypeo-labral region protrudes less than in any other of the species of western Palearctic’. The protrusion of the clypeo-labral region in X. gadagkari is more pronounced than X. vesparum ( Fig 15d of this study compared with Fig 2D of the study on X. vesparum ( Richter et al., 2017) . Kinzelbach (1978) further described that ‘the posterior delimitation of the brood aperture is shifted far forward’ while the lateral margins of the brood aperture reach the anterior margin of the head. In X. gadagkari , neither of these two characters is different from X. vesparum i.e. the posterior delimitation of the brood aperture is not shifted forwards and the lateral margins of the brood aperture end way before reaching the anterior margin of the head. Although body size may vary between hosts, a morphometric and colour comparison of X. gadagkari with the available data from X. vesparum and X hebraei is compiled in table 2 .

Figures

FIGURE 2. Abdomen of a female wasp with double infections (2a, b) and triple infections (2c, d). Left panel: Before sclerite removal, Right panel: After sclerite removal.

FIGURE 15. a. Cephalothorax of female X. gadagkari with planidia larvae collected from P. wattii. b, c and d SEM images of the female cephalothorax. SBHP—Segmental border between head and prothorax, PL—Planidium larvae, OS—Mouth Opening BC—Opening of the Brood Canal, SES—Semicircular field possible of labral region, MX—Maxilla, MD—Mandible.

FIGURE 17. A Baysian phylogenetic tree of partial mitochondrial CO1 sequences constructed using GTR+g+i model in MrBayes for different species of Xenidae family. X. gadagkari sequences generated for this study are represented in purple. Homologue from Stylops advarians (host: Andrena milawaukeensis) was used as an outgroup. Numbers above the nodes indicate clade credibility values. Names of the hosts and their family are given against the sequences. Host name was not available for X. hamiltoni in the paper associated with the accession number. However, X. hamiltoni is usually found in Polistes carnifex (Kathirithamby & Hughes, 2006).