«Taxonomic Revision, Molecular Phylogeny and Zoogeography of the huntsman spider genus Eusparassus (Araneae: Sparassidae) Dissertation for attaining ...»
Synapomorphies for this subfamily are the trilobate membrane with well developed lateral projections and median hook, and chelicerae with three anterior and four to six posterior teeth, intermarginally covered with denticles (mostly a patch of denticles is present close to the three anterior teeth; Jäger, 1998). Within the Heteropodinae the genera Heteropoda, Spariolenus Simon, 1880 and Sinopoda Jäger, 1999 were grouped together with the highest support.
Heteropoda and Sinopoda were already considered closely related given both somatic and copulatory structures (Jäger, 1999b). On the other hand, Spariolenus was proposed to be closer to Barylestis Simon, 1910 (Jäger, 2006; Moradmand and Jäger, 2011), but was here recovered sister to Heteropoda, while Barylestis was sister of Pandercetes L. Koch, 1875. The placement of the genus Pseudopoda [including the type species P. prompta (Pickard-Cambridge, 1885)] within the Heteropodinae clade was not fully resolved.
We also included a member of the New World Heteropodinae from the Caribbean Islands (Olios cf. sanctivincenti (Simon, 1897)) which, according to a personal communication of C. A. Rheims, belongs to an unknown genus misplaced in Olios) that did not cluster with the Old World
Results: chapter 3.3: Molecular phylogeny
The genera Palystes L. Koch, 1875, Parapalystes Croeser, 1996 and Panaretella Lawrence, 1937 represented a well supported monophyletic group in most analyses (Fig. 3). The grouping is congruent with the subfamily Palystinae and its diagnostic characters studied and proposed by Croeser (1996) and Jäger and Kunz (2010), including eye arrangement and chelicerae with three anterior and three posterior teeth lacking intermarginal denticles. The Palystinae are endemic to tropical Africa (Croeser 1996). According to weak diagnostic characters (Jäger and Kunz, 2010) Parapalystes could be considered a synonym of Palystes. Our molecular data suggests this possibility, while otherwise the well-defined genus Palystes would appear paraphyletic. For further studies on Palystinae the genera Anchonastus Simon, 1898 and Sarotesius Pocock, 1898 also need to be included.
The Madagascan-Seychellois endemic Damastes Simon, 1880 was weakly recovered as a sister taxon to the Palystinae clade. The genus was classified as Deleninae by Simon (1903) but later transferred by Järvi (1912) to a sub-group of Heteropodinae named Toraniformes (Toraniae).
Jäger (2002) stated that the systematic placement of the genus within the family is still unclear.
Our phylogeny recovered Damastes neither close to Deleninae nor Heteropodinae, but the genus also cannot be interpreted as a member of Palystinae or another clade.
This currently monotypic subfamily, based on the genus Staianus Simon, 1889, clustered with the genera Rhitymna Simon, 1897 and cf. Remmius (Fig. 3). The relationship of the three genera is otherwise unresolved, while Remmius and Rhitymna are considered more closely related based on morphology. Staianus is distinctly different from another Madagascan genus Damastes (Jäger
Results: chapter 3.3: Molecular phylogenyand Kunz, 2005), and our molecular data suggests an independent origin of the two endemic genera, as well.
The Australian endemic group Deleninae is here represented by the genera Holconia Thorell, 1887 and Isopeda L. Koch, 1875, that grouped together with highest support in our analyses. The subfamily was established by Hogg (1903) to include several endemic Australian genera previously classified as Sparassinae by Simon (1897). Hogg (1903) distinguished Deleninae from Sparassinae by the characters of body shape and male palps which is backed here by molecular data. The monophyly of Deleninae was also recovered by Agnarsson and Rayor (2013) based on rich sampling within the subfamily but including few outgroup (e.g. Sparassinae).
Sparassinae was not recovered as monophyletic in our data set (Fig. 3). The type genus Micrommata (as senior synonym of Sparassus Walckenaer, 1805) (Jäger, 1999a) does not cluster with its assumed closest relatives Olios, Cebrennus Simon, 1880 and Cerbalus Simon, 1897. The cheliceral features thought to characterise this group may be symplesiomorphic characters (lacking intermarginal denticles and the presence of two anterior and three to six posterior teeth;
Jäger, 1998). Because of their general similarity in somatic characters the genera Eusparassus, Micrommata and Olios were previously summarised under the generic name Sparassus. Later, Jäger (1999) gave Micrommata priority over Sparassus, with the group again split into the three previously synonymous genera. Still, Olios remains a special case, being currently the largest Sparassidae genus (Platnick, 2013) and being used as a collective group for many undescribed taxa (Jäger and Kunz, 2005). Rheims (2010b) noted that the genus is most likely polyphyletic, which is supported in our analyses. While most other Sparassidae species of the same genus cluster together with high support, Olios cf. lacticolor Lawrence, 1952 and Olios cf.
sanctivincenti are placed far from the rest of the included Olios species. “True” Olios species, can be considered the type species Olios argelasius (Walckenaer, 1805), the morphologically similar O. lamarcki (Latreille, 1806) and O. sanguinifrons (Simon, 1906), are grouped together with strong support. Three other Olios species were recovered close to this core group, yet without their interrelationships further resolved. Rheims (2010b) supposed that of these the Nearctic Olios species (giganteus and bibranchiatus) may warrant an independent genus. Morphological
Results: chapter 3.3: Molecular phylogenycharacters (Jäger and Kunz, 2005) are in accordance with our molecular evidence to suggest that the southern African Olios species (auricomis and lacticolor) are different from each other and that O. lacticolor should be excluded from the genus. The two Afro-Asian desert dwelling genera Cebrennus and Cerbalus were grouped together with high support and were sister to the ensemble of the “True” and associated Olios species.
The Eusparassinae were not supported as monophyletic in our analyses, but given the unresolved Non-Sparianthinae clade backbone this possibility cannot be entirely rejected. The inferred phylogeny placed the assumed Eusparassinae genera (see Fig. 1) into two separate clades (Fig.
3); one contained the type genus Eusparassus and all of its representatives, and the second clade contained the remaining genera (here outlined as African clade) which grouped together with at least sufficient support from half the BI analyses. Eusparassus was thus recovered as isolated from Pseudomicrommata (both included in the initial composition of the subfamily; Järvi, 1912) and the latter grouped with high support with Arandisa Lawrence, 1938, also endemic to Africa and weakly affiliated with others in the African clade (Fig. 3). As noted before, Järvi’s (1912,
1914) classification used exclusively the female copulatory characters to group genera and ignored most of the somatic ones. Nevertheless, Eusparassus and Pseudomicrommata resemble each other in some structures, but also show significant differences in copulatory and somatic characters. For instance, Pseudomicrommata (and Arandisa) have distinct pockets on the lateral lobes of their epigynes (Jäger and Kunz, 2005) which are lacking in Eusparassus. Moreover, the size and arrangement of the eyes and the spination pattern of the legs are very different in the two groups. Eusparassus species have the anterior median eyes (AME) always larger or equal to the anterior lateral eyes (ALE) but in the remaining genera AME are smaller than ALE. In Eusparassus, legs always have two pairs of tibial spines ventrally while other genera (Pseudomicrommata and Arandisa) have three. Some Eusparassus species have intermarginal denticles in their chelicerae which are always missing in species of other genera. It should be noted that similar structured copulatory organs may have developed independently several times in Sparassidae, as has been shown in other groups of spiders (Forster, 1980). In general, the structure of copulatory organs (particularly in males) is known to evolve and change more rapidly compared to somatic characters (Eberhard, 2010). Thus, the general similarity in copulatory organs is also more likely to reflect a convergent evolution of these organs. The genus
Results: chapter 3.3: Molecular phylogenyPseudomicrommata is likely to be subsumed into a group of its own, along with the other African endemic genera Arandisa, Leucorchestris, Lawrence, 1962, Carparachne Lawrence, 1962, Microrchestris Lawrence, 1962 and Palystella Lawrence, 1928. The phylogenetic relationships between the African clade and Eusparassus needs to be further resolved, including with more material and molecular markers.
According to morphological characters, the Asian genus Rhitymna was already proposed not belong to Eusparassinae (Jäger, 2003). In agreement, our current phylogeny did not support a close relationship of Rhitymna to Eusparassus or Pseudomicrommata, but placed it within a group encompassing Staianinae, the unplaced cf. Remmius and the type of the probably polyphyletic Sparassinae (Micrommata) as sister to these three genera.
3.5. Eusparassus The genus Eusparassus received strong support, combining all species assigned to this genus including the type species E. dufouri Simon, 1932 (using tissue of the neotype). The monophyly of each of the dufouri-, doriae- and walckenaeri-group was recovered, generally with high support (Fig. 3). The phylogenetic results correspond with the majority of the morphological characters (a combination of somatic and genital characters) used to group Eusparassus species (Moradmand, 2013). The deep divergence within some species (e.g. E. levantinus Urones, 2006 in Iberia or E. walckenaeri in Eastern Mediterranean) may indicate the presence of cryptic species. As noted in section 3.3.6 many Olios species probably require reassignment, as was done for the species E. laevatus (Simon, 1897) and E. tuckeri (Lawrence, 1927) now placed in Eusparassus (Moradmand, 2013). Our molecular phylogeny supports these nomenclatural acts. In contrast, O. sanguinifrons, originally described in Eusparassus (Simon, 1906), is here confirmed to be an Olios species close to the type species O. argelasius, as transferred by Jäger et al. (2002).
Another recent taxonomic proposal supported by this study is the synonymy of Cercetius with Eusparassus (Moradmand and Jäger, 2012b). Cercetius is nested within the Eusparassus clade, which is also congruent with the morphological information provided by Moradmand (2013).
Cercetius had not been assigned to any of the proposed Eusparassus species-groups and was considered as a lineage intermediate to the dufouri- jaegeri-, and walckenaeri-group.
(Moradmand, 2013), a placement not contradicted by the partly unresolved placement of the genus in our analyses. It is for now best retained as a single terminal taxon on the phylogenetic tree, however, the results point to a closer relationship with the walckenaeri-, doriae- and
Results: chapter 3.3: Molecular phylogenydufouri-group than with the jaegeri- and tuckeri-group members. The dufouri-group and Cercetius perezi was recovered as sister groups to the walckenaeri+doriae clade. One of the main somatic characters proposed to group Eusparassus species is the presence of the intermarginal denticles on the chelicerae, present only in the walckenaeri- and jaegeri-group (and in some specimens of Cercetius perezi). The homology of this character was not recovered in our analyses, as these groups did not form a clade. It is likely that gain of intermarginal denticles has taken place independently in both the walckenaeri- and jaegeri-group, or was lost in others. The phylogenetic reconstructions strongly supported the walckenaeri-group as sister to the doriaegroup. Moradmand (2013) suggested the doriae-group to be a lineage derived from the walckenaeri-group in Asia indicated by the loss of the intermarginal denticles of the chelicerae and by other subsequent modifications. Our data suggest that these groups are closely related phylogenetically. The placement of the single representative of the jaegeri-group in the tree, E.
jaegeri Moradmand, 2013, was not further resolved. The jaegeri-group is composed of four species endemic to southern Africa (Moradmand, 2013) and its unresolved position might result from the lack of other group members in the tree. The monophyly of the tuckeri-group, comprising E. tuckeri and E. educatus Moradmand, 2013, both endemic to SW Africa, was not recovered, but cannot be rejected either for the insufficient support at the connecting nodes.
Eusparassus educatus (and to some extent E. tuckeri) has an extraordinarily long embolus, unique among Eusparassus species (Moradmand, 2013). Finally, the inclusion of more species and additional data is necessary to further resolve the evolutionary history of Eusparassus.
3.6. Divergence time and historical biogeography
The divergence between Sparianthinae and other Sparassidae was estimated at 163 MA (95% HPD (highest posterior density) of 127–203 MA) by calibrating the “All-outgroups-8Sparassidae dataset” using four fossils (Fig. 4). The substitution rate (uncalibrated random local clock) increased slightly from about 0.8 in the outgroup taxa, Sparassidae and the basal Amaurobioidea-Agelenoidea-div.-clade, to 1.0 for the rest of RTA-clade members, but accelerated to 1.4 in the Salticidae-Philodromidae-Corinnidae clade (Appendix 1, Fig. 21).