Ramiplectrus, Yefremova & Feldstein-Farkash, 2025

Yefremova, Zoya A. & Feldstein-Farkash, Tamar, 2025, Ramiplectrus catiensis, a new genus and a new species with branched male antennae and long metatibial spurs from Vietnam (Hymenoptera: Eulophidae), Israel Journal of Entomology (Oxford, England) 54 (6), pp. 7-19 : 14-16

Key to the genera of Eulophinae with branched male antennal segments

1 Male antenna: F1 and F2 with branch, F3 and F4 without branches; scutellum with two sublateral grooves .................................................................................2

– Male antenna: F1, F2 and F3 with branch, F4 without branches; scutellum without sublateral grooves ............ Dahlbominus , Elasmus , Eulophus , Hemiptarsenus , Necremnus , Notanisomorphella , Microlycus , Pnigalio , Sympiesis

2 Mesoscutum without complete notauli; metatibia without spurs; mandibles well developed; branches of male antenna 2.0× as long as antennal scape; propodeum with distinct plicae........................................................................... Dicladocerus

– Mesoscutum with complete notauli; metatibia with 2 long spurs; mandibles small without teeth; branches of male antenna as long as antennal scape; propodeum without plicae..................................................................... Ramiplectrus gen. n.

Comments based on the molecular analysis

Based on our phylogenetic analysis, Ramiplectrus catiensis gen. et sp. n. is placed in the tribe Eulophini (subfamily Eulophinae ) ( Fig. 8 ). This allocation is also supported by the position of the propleural plates, which meet and cover the prosternum – a character typical for most genera in the tribe Eulophini . In the present 28S rRNA phylogenetic analysis, the tribe Eulophini is divided into two clades: Clade A includes Ramiplectrus gen. n., along with Dicladocerus , Elachertus , Euplectrus , Hoplocrepis Ashmead, 1890 , Hyssopus Girault, 1916 , Miotropis Thomson, 1878 , Paraolinx Ashmead, 1894 and Platyplectrus , and Clade B that includes the genera Sympiesis , Pnigalio , Hemiptarsenus , Eulophus and Elasmus . The bootstrap support for the

Clade A is 47, and for the Clade B is 29. These relatively low values are likely due to the limited number of variable positions in the D2 region of the 28S rRNA gene. As observed in previous studies ( Gauthier et al. 2000; Rasplus et al. 2020), the tribe Euplectrini , represented here by Euplectrus sp. and Platyplectrus sp. , forms a subclade within Clade A of Eulophini . These genera share two morphological features also found in R. catiensis sp. n.: long metatibial spurs and small mandibles. However, the 28S rRNA sequence of R. catiensis sp. n. is distinct and does not cluster directly with them.

Instead, R. catiensis sp. n. clusters with Miotropis sp. , which is characterized by a large pronotum (2.0–2.5× as broad as long; 2.5× in R. catiensis ), complete notauli, one pair of long setae on mesoscutal midlobe, mesoscutellum with two incomplete longitudinal grooves and a propodeum with a complete median carina. However, Miotropis spp. differ from R. catiensis sp. n. in having well-developed mandibles, unbranched male antennae, and in lacking long metatibial spurs. Male genitalia in Miotropis simplex Thomson, 1878 and M. nigriceps Suciu, 1980 have digiti bearing two spines ( Suciu 1980). Examination of a male of Miotropis unipuncta (Nees, 1834) labelled “Batorliget, Hungary, 1959. vii, 11, Dr. Erdös, det, Erdös” (SMNHTAU), confirmed that its antenna is unbranched.

The clustering of Ramiplectrus gen. n. with Miotropis sp. is likely an inaccuracy of the phylogenetic analysis (possibly due to long branch attraction), similar to the observed grouping of Hoplocrepis with Paraolinx , which are morphologically very different. To test this, a short 28S rRNA fragment (~180 bp) from Xanthellum Erdös & Novicky, 1951 ( Rasplus et al., 2020, SRX8128990) was included in our analysis. In this reduced dataset, Xanthellum sp. clustered with Hoplocrepis sp. , which is more congruent with morphology (topology not shown).

Our new species presents a unique combination of morphological characters – two notably long metatibial spurs and a branched male antennae. The distinct 28S rRNA sequence confirms the novelty of Ramiplectrus catiensis gen. et sp. n. among already sequenced genera.

Figures

Fig. 8. The phylogenetic tree of Eulophini 28S rRNAsequences, 424 bp D2 region.The new sequences of Ramiplectrus catiensis gen. et sp. n., Platyplectrus desertus and Euplectrus bicolor are marked with asterisk (*). The phylogenetic tree was reconstructed using PhyML 3.0 under the maximum likelihood criterion. Cirrospilini sequences are used to root the tree. Bootstrap supports are given near the corresponding nodes.