Leptogomphus, Selys in Borneo, 1878

Dow, Rory A., Stokvis, Frank & Ngiam, Robin W. J., 2017, Revision of the Genus Leptogomphus Selys in Borneo, including gene trees and a two marker molecular phylogeny (Odonata: Anisoptera: Gomphidae), Zootaxa 4358 (2), pp. 201-257 : 205-207

Leptogomphus of Borneo

Molecular analysis. Figures 1–3 show the results of molecular analyses. In each figure the best ML tree is shown, with posterior probabilities from the corresponding BI analysis included. Bootstrap support values and posterior probabilities are shown for each node if one of them is less than 100 or 1.0 respectively; these values are not shown for the outgroup taxa. Branches associated with the outgroup taxa have been shortened (indicated by ‘/’) to make the figures more compact. Relationships among Bornean species are discussed here, discussion of the results within species can be found in the remarks under each species below.

In the COI gene tree ( Fig. 1 ) the Bornean species plus the Philippine L. semperi form a clade, with the rest of the examined Leptogomphus species as a sister clade; support for the relationship of these two clades is high (ML) or complete (BI). Leptogomphus sp. cf coomansi is not resolved as a separate entity from L. coomansi , but L. coomansi is separated into two clades. Leptogomphus pasia and L. sii are sisters with high/complete support, but are well differentiated from one-another. Leptogomphus semperi appears as the sister of L. coomansi with high support, and L. pasia + L. sii form a sister clade to L. coomansi + L. semperi with high (complete in BI) support. Leptogomphus species cf williamsoni appears as distinct sister to L. williamsoni with complete support, and L. pendleburyi appears as a rather distant sister to L. species from Pulong Tau National Park with complete support in the BI analysis, but lower support in ML. The L. williamsoni + L. sp. cf williamsoni clade is the sister of the L. pendleburyi + L. species clade, but with low support in ML, this whole clade is the sister of the L. coomansi + L. semperi + L. pasia + L. sii clade, but again with low support in ML.

ITS was only successfully extracted and amplified for one non-Bornean Leptogomphus sample ( L. intermedius ), so the gene tree ( Fig. 2 ) throws little light onto the relationships of the Bornean species with the rest of the genus. In ITS two main clades are visible, one consisting of L. coomansi + L. sp. cf coomansi + L. sii + L. pasia , the other of L. willliamsoni + L. pendleburyi + L. species + L. intermedius ; support for this relationship is complete in BI but not in ML. Within the first clade, L. sp. cf coomansi is the close sister of L. coomansi with complete support in BI but not ML; the two clades visible in COI for L. coomansi are still present, but very weakly distinguished. Leptogomphus pasia and L. sii are close sisters, but support is not complete for their relationship in either analysis. The L. coomansi + L. sp. cf coomansi clade is the sister of the L. pasia + L. sii clade, but with less than complete support. In the second main clade L. williamsoni is the sister of L. pendleburyi + L. species + L. intermedius , but with less than complete support in BI and rather low support in ML. Leptogomphus pendleburyi is the sister of L. species with complete (BI) or high (ML) support, but support for the relationship of L. intermedius to the others is very weak; we suggest that its position in this gene tree is merely an artefact of poor taxon sampling for the non-Bornean species.

In the combined COI and ITS analyses ( Fig. 3 ), L. coomansi and L. sp. cf coomansi have the same relationship as seen with ITS alone, with complete support in the BI analysis, but lower support in ML. The same two clades are visible within L. coomansi as in the single marker analyses. Leptogomphus semperi appears as the sister of the L.

coomansi + L. sp. cf coomansi clade with complete support in BI but not ML. Leptogomphus pasia and L. sii again appear as sister species, with complete (BI) or nearly complete (ML) support; the L. pasia + L. sii clade is the sister of L. coomansi + L. sp. cf coomansi + L. semperi with complete (BI) or high (ML) support. The remaining taxa form a clade that is the sister of the clade containing all those already mentioned, with complete support in both analyses. However the lack of ITS for most of the non-Bornean samples gives little confidence in this relationship, so that we only discuss the relationships between the Bornean species here. Within this clade L. pendleburyi is the sister of L. species with complete support, and L. williamsoni and L. sp. cf williamsoni are sisters with complete support.

Considering only the Bornean species, each of the analyses generally supports relationships between the species that are rather obvious on morphological grounds. The close relationship between L. coomansi and L. sp. cf coomansi is clear on morphological grounds, as is the sister species relationship of L. pasia and L. sii , and L. williamsoni and L. sp. cf williamsoni , and the more distant relationship of the last pair with the other two. The relationships of L. pendleburyi are less obvious on morphological grounds; the picture emerging from the molecular analyses appears plausible, but an expanded analysis is desirable to confirm it.

Figures

FIGURE 2. ITS gene tree for 20 specimens of Leptogomphus and three outgroup taxon.The best Maximum Likelihood tree is shown, with posterior probabilities from the Bayesian Inference analysis also depicted on the branches. Bootstrap values and posterior probabilities are shown if less than 100 or 1.0 respectively. RMNH collection codes are shown for each specimen, as well as the sex of the specimen and an indication of where it was collected.

FIGURE 3. Phylogenetic reconstruction for 30 specimens of Leptogomphus and three outgroup taxa using the combined COI+ITS dataset. The best Maximum Likelihood tree is shown, with posterior probabilities from the Bayesian Inference analysis also depicted on the branches. Bootstrap values and posterior probabilities are shown if less than 100 or 1.0 respectively. RMNH collection codes are shown for each specimen, as well as the sex of the specimen and an indication of where it was collected.

FIGURE1. COI gene tree for 29 specimensof Leptogomphusand three outgroup taxon.The best Maximum Likelihood tree is shown, with posterior probabilities from the Bayesian Inference analysis also depicted on the branches. Bootstrap values and posterior probabilities are shown if less than 100 or 1.0 respectively. RMNH collection codes are shown for each specimen, as well as the sex of the specimen and an indication of where it was collected.