Ruptor cordatus, Żyła & Bogri & Hansen & ShaW & Kypke & Solodovnikov, 2022

Żyła, Dagmara, Bogri, Amalia, Hansen, Aslak Kappel, ShaW, Josh Jenkins, Kypke, Janina & Solodovnikov, AleXey, 2022, A New Termitophilous Genus of Paederinae Rove Beetles (Coleoptera, Staphylinidae) from the Neotropics and Its Phylogenetic Position, Neotropical Entomology 51 (2), pp. 282-291 : 287-288

Ruptor cordatus sp. nov.

Type material, Holotype: [card mounted, DNA extraction voucher]: ♂, ‘ PER17-19a , PERU: Amazonia, Loreto region, Maynas province, Allpahuayo-Mishana NP , 20 km S of Iquitos , 3.IX.2017 / 100–200 m, 3°57.812′S 73°25.142′W, rainforest, in termite nest, leg. A. Hansen, J. Kypke, A. Solodovnikov /HOLOTYPE Ruptor cordatus gen. et sp. n. Żyła et al. des. 2021 [red label]’ ( MHN-UNMSM) . Paratypes: [card mounted]: 1♀ ‘ PER17-19a PERU: Amazonia, Loreto region, Maynas province, Allpahuayo-Mishana NP , 20 km S of Iquitos , 3.IX.2017 / 100–200 m, 3°57.812′S 73°25.142′W, rainforest, in termite nest, leg. A. Hansen, J. Kypke, A. Solodovnikov / collected with the holotype/PARATYPE Ruptor cordatus gen. et sp. n. Żyła et al. des. 2021 [yellow label]’ ( NHMD) ; [disarticulated, in glycerin]: 1♀, ‘PER17-20a , PERU: Amazonia, Loreto region, Maynas Province, Allpahuayo-Mishana NP , 20 km S of Iquitos , 4.IX.2017 / 100–200 m, 3°58.725′S 73°25.497′W, rainforest, in termite nest, leg. A. Hansen, J. Kypke, A. Solodovnikov / PARATYPE Ruptor cordatus gen. et sp. n. Żyła et al. des. 2021 [yellow label]’ ( MHN-UNMSM) ; [in cryovial]: 1♀, ‘ PER17-21b , PERU: Amazonia, Loreto region, Requena province, 3 km E of Jenaro Herrera , 6.IX.2017, 100–200 m / 4°54.022′S 73°39.104′W, secondary forest/plantation, in termite nest, leg. A. Hansen, J. Kypke, A. Solodovnikov / PARATYPE Ruptor cordatus gen. et sp. n. Żyła et al. des. 2021 [yellow label]’ ( NHMD) .

Measurements of holotype (in millimetres). Length = 4.9; front body length (HL+ PL + EL) = 2.27; HW (head width at widest point) = 1.0; HL (head length medially) = 0.6; PW (pronotum width at widest point) = 1.1; PL (pronotum length medially) = 0.78; EW (elytra width at widest point) = 1.18; EL (elytra length from shoulder to hind margin) = 0.89.

Description

Body colouration varies from pale brown to dark brown; head and elytra always darker; pro- and mesotibia darker than metatibia. Anterior and posterior margins of head, pronotum and elytra evenly covered with short golden setae; rest of head and abdomen mainly with grey setae; disc of head appearing dull due to microsculpture between fine punctation. Antennae: antennomere 1 as long as two following antennomeres; 2 and 3 elongate; 4 to 8 clearly transverse, 9 and 10 slightly transverse, 11 elongate, 1.5 × longer than antennomere 10. Antennomeres 3 to 7 appearing bicoloured, apical third of each antennomere distinctly darkened. Pronotum slightly longer than head. Elytra slightly longer than, and about as wide as pronotum; punctation with punctures larger and more densely positioned than those on pronotum. Aedeagus with narrowly pointed median lobe and characteristically elongate, bifurcate sclerite of internal sac.

Distribution and bionomics

Ruptor cordatus sp. nov. was found inside the chambers of arboreal termite nests ( Fig. 1 ) in the lowland forest of the North-Eastern Peru ( Fig. 2 ). The termite host was confidently identified as a widespread Labiotermes labralis ( Figs. 1 and 2 ), the only species in the genus that builds an arboreal nest ( Constantino et al. 2006). Based on our sampling, we were able to find Ruptor cordatus sp. nov. in roughly every fourth termite nest that was searched. All nests where Ruptor cordatus sp. nov. was found were with winged termites, where also a number of other inquiline staphylinids (mostly Aleocharinae ) were always encountered.

Etymology

The scientific name of the new species is a Latin adjective that refers to the cordate shape of the head of the new species due to its characteristic notch in the middle of the hind margin of the head.

Phylogenetic analyses

PartitionFinder found the following four partitions: (1) 28S + COI2 + ArgK2 + Wg2 + TP2 + CADC2 + CADA2 + COI1 + ArgK1 + CADC1 + CADA1 + Wg1 + TP1; (2) Wg3 + TP3 + ArgK3; (3) CADA3 + CADC3; (4) COI3. For partition 1, SYM + I + G was found to be the best-supported model, for partitions 2 and 3—GTR + I + G, and for partition 4—HKY + G. We moved 28S to a separate partition as this is the only non-protein-coding gene in our dataset and analysed it under the SYM + I + G model. The third codon positions of COI were excluded as it has been suggested that they suffer saturation for deep divergences, which can potentially bias phylogenetic analyses (e.g. Swofford et al. 1996; Lin and Danforth 2004). Since COI3 was excluded, no partition was analysed under the HKY + G model.

The BI analysis reached convergence, with a standard deviation of split frequencies well below 0.01 after 10 million generations. Mixing of the Markov chain Monte Carlo chains was good, effective sample size (ESS) values were greater than 200 for all parameters indicating good mixing of the chains and the observed PSRF was 1.00. Convergence was also visualised in Tracer v1.7.

The tree topology presented in Fig. 6 is the 50% majority rule consensus tree. The subfamily Paederinae was recovered as monophyletic with strong support (posterior probability PP=1) as well as Paederini , Pinophilini and Lathrobiini , its three currently recognised tribes (PP= 1 in all cases). Within Lathrobiini , the first clade ( Dysanabatium Bernhauer, 1915 + ( Notobium Solsky, 1864 + Phanophilus Sharp, 1886 )), all three genera currently classified in Lathrobiina , was well-supported (PP=1). The next clade ( Pseudolathra Casey, 1905 +( Neolindus Scheerpeltz, 1933 + Cylindroxystus Bierig, 1943 )) was the Pseudolathra - Cylindroxystina lineage recently discovered in Żyła et al. (2021), which was well-supported here too (PP=0.99). The next resolved clade ( Tetartopeus Czwalina, 1888 +( Lathrobium Gravenhorst, 1802 + ( Domene Fauvel, 1873 + ( Lobrathium Mulsant & Rey, 1878 + Platydomene Ganglbauer, 1895 )))) was the so-called ‘true’ Lathrobiina (PP=1), recovered as sister to the ‘ Medonina and allied taxa’ clade (sensu Żyła et al. 2019) with weak support (PP = 0.84). Within the ‘ Medonina and allied taxa’ clade, the clade ( Enallagium Bernhauer, 1915 [ Lathrobiina ] + ( Scopaeus Erichson, 1839 [ Scopaeina ] + unidentified specimen of a Medonina from the Far East Russia)) branched off first with strong support (PP= 1). The subtribe Medonina was recovered as non-monophyletic, where its bigger fraction formed a group largely paraphyletic with respect to other subtribes in this clade, i.e. Scopaeina , Stilicina , Astenina , Stilicopsina and Echiasterina . Rugilus Leach, 1819 + Stilicoderus Sharp, 1889 (both Stilicina ) and Eustilicus Sharp, 1886 ( Stilicina )+ Thinocharis Kraatz, 1859 ( Medonina ) were altogether recovered as a strongly supported clade (PP=1). Dibelonetes Sahlberg, 1847 and Stilicopsis Sachse, 1852 (both Stilicopsina ), as well as Echiaster Erichson, 1839 and Ronetus Blackwelder, 1943 (both Echiasterina ) were resolved as monophyletic clades (PP= 1 in both cases), with Stilicopsina sister to Astenus Dejean, 1833 ( Astenina ) (PP=0.85). Our new genus was recovered as deeply nested within the ‘ Medonina and allied taxa’ clade. There, it was resolved as sister to a heterogeneous clade formed by the majority of sampled members of Medonina (all, except for Medonina from Far East Russia and Pseudomedon Mulsant & Rey, 1878 ) and all sampled Scopaeina , Stilicina , Astenina , Stilicopsina and Echiasterina .

Figures

Fig. 1 Rove beetle Ruptor cordatus gen. et sp. nov. and its termite host Labiotermes labralis (Holmgren, 1906). a Arboreal termite nest of Labiotermes labralis; b worker specimen of Labiotermes labralis; c live specimen of Ruptor cordatus photographed on the disassembled termite nest debris before being collected

Fig.2 Distribution of Ruptor cordatus gen. et sp. nov. (orange star) and its termite host Labiotermes labralis (Holmgren, 1906) (blue circle), the latter based on Constantino et al. (2006)

Fig. 6 Bayesian Inference (BI) 50% majority rule consensus phylogenetic tree. Nodes with (BI) posterior probability (PP)>0.95 were considered well supported, nodes with PP=0.90–0.94 moderately sup- ported, those with PP=0.80– 0.89 weakly supported and nodes with PP<0.79 were considered to be unsupported