Triaenonychidae, Sorensen, 1886

Derkarabetian, Shahan, Baker, Caitlin M., Hedin, Marshal, Prieto, Carlos E. & Giribet, Gonzalo, 2021, Phylogenomic re-evaluation of Triaenonychoidea (Opiliones: Laniatores), and systematics of Triaenonychidae, including new families, genera and species, Invertebrate Systematics 167 (1), pp. 277-288 : 148-153

Systematics of Triaenonychidae

Here we discuss each of the major lineages within Triaenonychidae , cover relevant taxonomic history and morphological characteristics, provide hypothesised placement of unsampled genera, and highlight potential for future revisionary work. Although there are differences in relationships among major clades across phylogenetic analyses, essentially all major clades and subclades are recovered, with the exception of a few individual taxa showing uncertain placement noted below. We present our discussion based on the IQ-TREE results, noting any uncertainty with the BEAST and SVDQuartets phylogenies in the relevant sections.

Clade A

Clade A is found in eastern Australia and New Zealand. Morphological phylogenetic studies placed Pyenganella as sister group to Lomanella , sharing several characters including some in the male genitalia ( Hunt 1996; Mendes 2009). However, this was a hypothetical placement in Hunt (1996), and not the actual result of analysing his morphological dataset (see his fig. 1 and 2), and was obtained only with particular character weighting schemes in Mendes (2009), who also emphasised caution in this relationship. In the other analyses of Mendes (2009), Pyenganella was recovered as an early diverging core triaenonychid. In our analyses, Pyenganella is always found as sister group to the New Zealand endemic genera Hendea and Hendeola Forster, 1954 . A potential synapomorphy for these three genera might be found in the male genitalia: on the ventral plate the single superior seta on each lobe is noted to be stronger and stouter than the 2 – 3 pairs of inferior setae, as noted by Forster (1954) for Hendea and Hendeola . Hickman (1958) noted that the superior setae of Pyenganella are longer than the inferior, but we add that they are also slightly stouter (S. Derkarabetian, pers. obs.)

This clade also includes what we call the ‘ Equitius group’ from eastern Australia, with a fairly complicated taxonomic history. The genus Monoxyomma Pocock, 1903 was a superficial group of taxa united by the number of tarsal segments on leg I. The type species was M. spinatum Pocock, 1903 , and the genus later included two other species from Queensland, Australia: M. manicatum Roewer, 1920 and M. rotundum Forster, 1955 . In a revision of Equitius Simon, 1880 , Hunt (1985) synonymised the type species M. spinatum with Equitius (as E. spinatus ), but stated that the other two species belong to a ‘new genus together with some undescribed species ranging from northern Queensland to southern New South Wales’. It is unclear whether this undescribed genus has a continuous distribution along eastern Australia or a disjunct distribution; Hunt (1985) states that ‘ Equitius is replaced ’ (emphasis added) in the north and south by species of this new genus, implying allopatry. Across studies, Hunt refers to multiple undescribed genera: the one mentioned above (discussed in Hunt 1985) and ‘new genus C’ and ‘new genus D in Hunt (1996) ’. Both of these new genera were included in the phylogenetic analyses of Hunt (1996) and recovered in a clade with Equitius . (Hunt never explicitly mentioned ‘new genus A’ and ‘new genus B’ implied by the previous statements.) It is likely that one of the new genera in Hunt (1996) is the undescribed genus mentioned in Hunt (1985), and equally likely that both of these genera are represented as sequenced specimens recovered in Clade A. Our sample of MCZ:IZ:23313 collected from southern Queensland may likely be a northern representative of this undescribed genus, whereas the two we have identified as ‘ Equitius ’ cf. Monoxyomma (MCZ:IZ:152643 and NHMUC:Aus10b) may be the southern representatives. In the checklist of Triaenonychidae, Kury et al. (2014) included M. manicatum and M. rotundum in Equitius . Given the comments of Hunt (1985), we consider these incertae sedis as the genus level and label them as ‘ Equitius ’. The ‘ Equitius group’ including the potential (and yet another) undescribed genus from the Otway Ranges of Victoria (MCZ:IZ:152660 and SDSU_TAC: OP2779) will require more detailed taxonomic attention.

Clade B

Clade B is exclusively found in South Africa, with the exception of Ceratomontia argentina from South America (MCZ:IZ152640, discussed below). Species in this clade are typically smaller in size relative to the other South African taxa (Clade D1). Kauri (1961) proposed two main groups, the ‘ Ceratomontia group’ and the ‘ Roewerania group’, divided according to the respective presence or absence of a longitudinal band of small granules ventrally on the pedipalp femur. Both groups are paraphyletic in our analyses. Kauri’ s ‘ Ceratomontia group’ mostly corresponds to Clade B, except that in our analyses Paramontia Lawrence, 1934 and Planimontia Kauri, 1961 are included, and Micromontia Lawrence, 1939 is excluded. Taxa from Kauri’ s ‘ Roewerania group’ are predominantly found in subclades D1 and D2, those subclades containing all the other South African taxa. More recently, Kury (2004) described the genus Lizamontia Kury, 2004 for the three South African species that were included in the otherwise entirely Madagascan genus Acumontia Loman, 1898 , to which they are not closely related. These species were originally included as part of Kauri’ s ‘ Roewerania group’, but in our analyses the genus constituted an early-diverging lineage of Clade B, closely related to the ‘ Ceratomontia group’ taxa, a relationship perhaps reflected in its morphology. As detailed in Kury (2004), compared to the ‘ Ceratomontia group’ sensu Kauri, Lizamontia lacks the ventral longitudinal band of small granules, and, unlike most other South African taxa, Lizamontia lacks sexual dimorphism in the chelicerae and stout spines on the pedipalp femur. A potential synapomorphy for Clade B, found in the male genitalia, is fused parastyli that wrap around the stylus like a coat (e.g. Kauri 1961; Kury 2004), but all presumptive genera of this clade have not been examined. It is likely that a specieslevel revision of this lineage will find that some South African genera are paraphyletic; indeed, Baker et al. (2020 b) recovered a polyphyletic Biacumontia Lawrence, 1931 . Many taxa are differentiated by leg tarsus segmentation, and species assignment and identification can be ambiguous based on available descriptions, the majority of which were done by R.F. Lawrence in the 1930s before the standardised use of genitalic morphology in Opiliones systematics. The unsampled monotypic genus Lispomontia Lawrence, 1937 potentially falls in this clade. Lawrence (1937 b) discusses its resemblance to Ceratomontia and Biacumontia based on tarsal formula, and its resemblance to ‘ Cryptobunus ’ (now Amatola Lawrence, 1931 ) and Biacumontia based on cheliceral morphology.

As currently defined, Ceratomontia is one of two transcontinental triaenonychid genera, with four species in South America largely distributed east of the Andes in Argentina, Uruguay, and south-eastern Brazil, and 18 species found in South Africa. Each regional group is represented in our dataset by a single sample and our analyses support paraphyly, a result also found in the morphological analyses of Mendes and Kury (2008). In their study, the South African Ceratomontia species were more closely related to the South African genera Monomontia and Austromontia , having several apomorphic characters not shared with the South American Ceratomontia , such as a ventral plate with a narrower base relative to the apex. Our results thus concur with earlier work that Ceratomontia is not monophyletic, and therefore is not a trans-Atlantic genus. The South American Ceratomontia have a penis with an undivided ventral plate and five setae on each side of the stylus, whereas the South African group has a cleft ventral plate and four setae on each side. The type species of the genus is C. capensis Roewer, 1915 from South Africa, necessitating a new genus name for the South American Ceratomontia lineage. However, we refrain from doing so until more South American Ceratomontia can be included in molecular phylogenetic analyses.

Clade C

Clade C is entirely South American, with the exception of Hedwiga Roewer, 1931 from New Zealand. The monotypic Picunchenops is a single-site cave-obligate species from Argentina that shows extreme troglomorphy, including complete loss of eyes. When it was described, Maury (1988) placed it into Triaenonychidae based on male genitalia, but could not confidently assign it to any of the triaenonychid subfamilies. Later, Kury (2003) placed Picunchenops in the subfamily Triaenonychinae (tribe uncertain). Another lineage within Clade C comprises a set of closely related taxa including Triaenonyx Sørensen, 1886 , all of which share a fairly similar male genitalic morphology, with an elongate and sometimes uniquely complex stylus ( Maury 1987 a, 1987 b, 1988; Pérez-González and Werneck 2018) that is hypertrophied in the case of Araucanobunus Muñoz Cuevas, 1973 ( Hunt and Maury 1993). Described as one of two South American genera in Triaenobuninae , the monotypic Araucanobunus was hypothesised to be closely related to Ankaratrix , the only Triaenobunine from Madagascar ( Muñoz-Cuevas 1973). Although MuñozCuevas (1973) noted many differences between Araucanobunus and Americobunus Muñoz Cuevas, 1972 , comparisons with other South American taxa were lacking, largely because few South American triaenonychids were known at this time. The Triaenonychidae type genus Triaenonyx consists of six species, five of which were described before 1916. The inclusion of Hedwiga in this clade was unexpected and no morphological similarities are obvious.

Clade D

Subclade D1. This clade is found in South Africa, with the exception of the South American Nuncia verrucosa Maury, 1990 (MCZ:IZ:138122). The species Nuncia verrucosa is representative of a lineage with similar somatic morphology that also includes N. spinulosa Maury, 1990 , and potentially N. rostrata Maury, 1990 . The type species of Nuncia is N. obesa (Simon, 1899) , found in the diverse New Zealand Nuncia E2 subclade. As such, this South American lineage will need a new genus name. We refrain from naming this clade here as not all South American Nuncia were sampled, but their position among South African species was also found in the Sanger-based phylogeny of Baker et al. (2020 b). Speleomontia Lawrence, 1931 was one of two South African genera included in the subfamily Sorensenellinae , and based on our results are completely unrelated to the Sorensenellinae from New Zealand: Sorensenella Pocock, 1902 and Karamea Forster, 1954 . The South African ‘ Adaeum group’ includes several genera that share very similar somatic morphology to that of Adaeum Karsch, 1880 , typically large-bodied with a highly denticulate dorsal scutum, often found dirt-encrusted. Based on this morphology, it is almost certain that the unsampled genera Cryptadaeum Lawrence, 1931 , Micradaeum Lawrence, 1931 , Montadaeum Lawrence, 1931 , Paradaeum Lawrence, 1931 , and Heteradaeum Lawrence, 1963 fall into the ‘ Adaeum group’ as well ( Lawrence 1931, 1963). These taxa are largely differentiated by the structure of the sternum and tarsal claw segmentation. This lineage essentially corresponds to the subfamily Adaeinae as currently defined, excluding Dingupa Forster, 1952 from Australia. In the BEAST and SVDQuartets analyses D1 is sister group to Clade E, rendering Clade D paraphyletic. Similarly, both analyses placed Mensamontia in Clade C.

Subclade D2. This subclade includes the three South African genera Roewerania Lawrence, 1934 , Graemontia Staręga, 1992 , and Micromontia . The male genitalia of Roewerania and Graemontia both show a deeply cleft dorsal plate ( Kauri 1961; Kury 2006). This lineage likely includes the unsampled genera Austronuncia Lawrence, 1931 , the monotypic Gunvoria Kauri, 1961 , and the monotypic Yulella Lawrence, 1939 . Gunvoria also shows a deeply cleft dorsal plate ( Kauri 1961). Yulella natalensis ( Lawrence, 1937) was originally described as a species of Roewerania ; Lawrence (1963) noted morphological similarities between Austronuncia and Yulella , and A. spinipalpus Lawrence, 1931 has extremely (and unusually) elongate pedipalps and chelicerae, much like Roewerania lignicola Lawrence, 1934 ( Lawrence 1931, 1934). Although the BEAST analyses recover a paraphyletic D2 with respect to D3, the unsampled taxa would still be associated with D2 genera in a D2 + D3 clade.

Subclade D3. This clade includes all taxa from Madagascar, excluding Flavonuncia and Ankaratrix , most of which were described by Lawrence (1959) and have remained largely unstudied since then. Many of these genera show extremely similar somatic morphology (e.g. Acumontia ): large bodied, most with large dorsal spines on the scutum, an elongate spine on the eye mound, and leg I with 4+ tarsal segments. The only genus not fitting this general pattern is Hovanuncia Lawrence, 1959 , which lacks spines on the eye mound and scutum and only has three tarsal segments on leg I. In a checklist of Afrotropical Opiliones, Staręga (1992) states a synonymy for Flavonuncia and Hovanuncia ; however, this synonymy only appeared in the abstract and was never followed, not even in the checklist included in the same paper. Obviously, these genera are distinct. The unsampled Madagascan genera Ivohibea Lawrence, 1959 , Millomontia Lawrence, 1959 , and Millotonyx Lawrence, 1959 will almost certainly fall in this clade: all three genera share the same general body plan as Acumontia and similar genitalic morphology. A sequenced specimen which could not be assigned to an existing genus based on morphology (MCZ:IZ:52828) potentially represents a new genus.

Subclade D4. This clade includes Ankaratrix from Madagascar as the sister group to three genera that are either endemic to Western Australia ( Breviacantha Kauri, 1954 and Dingupa ) or South Australia ( Yatala Roewer, 1942 ). Recently, Porto and Pérez-González (2020) explored soil crypsis in Ankaratrix while also describing four new species. The unsampled genus Perthacantha Roewer, 1931 is also likely included in this clade, as Hunt (1996) stated ‘ Perthacantha Roewer 1931 (= Dingupa Forster 1952 )’, though without any explanation or justification. We are keeping these two genera distinct until a more direct comparison can be made. Our examinations of Dingupa show that the male genitalia are similar to the drawings for Breviacantha gisleni Kauri, 1954 ( Kauri 1954) . In the SVDQuartets analysis, subclade D4 is not monophyletic with Ankaratrix grouped with subclade D2, although with weak support.

Subclade D5. This is a widespread Australian lineage that somewhat corresponds to a group recovered in Hunt’ s (1996) morphological phylogenetic analyses, though it does not include Calliuncus Roewer, 1931 . This group had an apomorphy of a penis stylus completely enveloped by plates, a character shared with taxa in Clade E1 (where we find Calliuncus instead). The Tasmanian genera Notonuncia Hickman, 1958 , Bryonuncia Hickman, 1958 , and Ankylonuncia Hickman, 1958 were recovered as a closely related group. As shown in Hunt (1996) Bryonuncia and Ankylonuncia were not recovered in the above-mentioned group, and hence do not share this apomorphy. However, they were found to be each other’ s closest relatives united by a penis with a ‘mid-dorsal large spiny lobe’. It is possible that re-examination and reinterpretation of genitalia may find that the ‘large spiny lobes’, which do surround the stylus (e.g. Ankylonuncia barrowensis Hickman, 1958 ), are homologous to the ‘plates enveloping the stylus’. The monotypic genus Tasmanonyx is unique in this lineage in having hind claws with the lateral branches longer than median prong, a characteristic shared with the nonmonophyletic Sorensenellinae . The unsampled genus Leionuncia Hickman, 1958 most likely falls in this clade, close to Notonuncia , as recovered in Hunt (1996).

The ‘ Nunciella group’ includes two deeply divergent clades. In our results, the genus Nunciella Roewer, 1929 is paraphyletic across three different lineages: (1) a clade including the Nunciella samples from Western Australia (MCZ:IZ:35908 and MCZ:IZ:132908) and N. cheliplus Roewer 1931 from Victoria; (2) N. kangarooensis Hunt, 1971 , a species endemic to Kangaroo Island, South Australia; and (3) N. tasmaniensis Hickman, 1958 from Tasmania. This non-monophyly is not surprising given the fact this genus is diagnosed by the number of tarsal segments of the first leg and Hunt’ s (1985) statement that Nunciella contains ‘a miscellany of species of doubtful affinity’. The type species of Nunciella is N. aspera (Pocock, 1902) , a species known from Western Australia, although Pocock’ s original description states the location for this species (then called Triaenonyx aspera ) as just ‘Australia’. Two new genus names will be needed for ‘ Nunciella ’. However, we do not name new genera here as detailed analyses of Nunciella are required. In this group, we also identify a new genus, called ‘new genus B Australia NHMUC:Aus025b’ ( Fig. 1 J ), which differs from related taxa in both somatic and male genitalic morphology. The two specimens sequenced are both from the Otway Ranges, Victoria, but we refrain from describing this genus here until more specimens can be obtained for detailed anatomical study.

A species currently known as Nuncia unifalculata is recorded from the extremely isolated Crozet Islands, which have never had a continental connection. This species was first described as Promecostethus unifalculatus by Enderlein (1909) based on four specimens, three immatures and one adult. However, upon examination, Roewer (1923) concluded that all specimens were immature, and postulated that it may belong to the transcontinental genus Nuncia . Later, Hickman (1939) redescribed this species based on a large set of adult specimens and formally transferred it to Nuncia . Forster (1954), when describing the New Zealand Nuncia (i.e. true Nuncia ) and considering Hickman’ s description, concluded that N. unifalculata does not belong in Nuncia and ‘should in fact be placed in either Nunciella or Neonuncia ’. The catalogue of Kury et al. (2014) lists this species as Promecostethus unifalculatus . We agree with Forster (1954): N. unifalculata does not belong to any lineage of Nuncia , and based on the description it is most similar to Nunciella and would therefore fall here in subclade D5. We further hypothesise, based on pedipalp spination, that this species is derived from the Western Australian Nunciella , related to N. aspera . This species must represent a long-distance dispersal event, but whether it differs at the genus level from Nunciella (or another potential source) is uncertain as no genitalia were ever drawn and specimens could not be obtained for this study. Despite previous synonymy, we follow Kury et al. (2014) and use the name Promecostethus unifalculatus for this species to signify its distinctiveness from Nuncia , while not adding a new name to potential future synonymy. Examination of genitalia and inclusion in a molecular phylogeny is needed to confirm its genus-level placement.

Clade E

Subclade E1. This subclade includes taxa from South America and Australia. The relationship among these taxa is not surprising as male genitalic morphology is very similar ( Muñoz Cuevas 1971 a, 1971 b; Hunt 1972), with the stylus enclosed in a cup-like structure, a character shared with subclade D5. Although genitalia for Callihamus Roewer, 1931 and Callihamina Roewer, 1942 were not examined in initial descriptions, the sample of Callihamina included in our study (NHMUC:18A) is a male and our examination of the genitalia confirms this character. The Australian genera Calliuncus , Callihamus and Callihamina are all very similar morphologically and diagnosed solely based on the number of tarsal segments of leg II. Calliuncus is a widespread genus found in Western Australia, Victoria and Tasmania, and appears paraphyletic with respect to the other two genera. Callihamus badius Roewer, 1931 is known only from near Melbourne, Victoria, and Callihamina adelaidia Roewer, 1942 is known only from near Adelaide, South Australia ( Roewer 1931, 1942). Whereas our sample of Callihamus (MCZ:IZ:152666) is from the Otway Ranges, fairly close to the type region of Melbourne, our sample of Callihamina (NHMUC:18A) is from New South Wales, extremely distant from the type locality of Adelaide. Despite this distance, the specimen keys to Callihamina , again distinguished from the other genera solely based on the number of tarsal segments. Given sampling of all Calliuncus species, synonymy of these three genera might be warranted. The unsampled genus Parattahia Roewer, 1915 , only including P. u-signatum Roewer, 1915 from Tasmania most likely falls in this clade. Parattahia is generally similar in somatic morphology, possessing a characteristic hook on the eye mound like the other taxa. Nuncia chilensis was initially described as Parattahia chilensis by Soares (1968), placing it in this genus because of its similarity to P. u-signatum. Hunt (1996) noted that Calliuncus is actually a junior synonym of Parattahia , but formal changes should not be made until P. u-signatum can be included in analyses.

Subclade E2. This subclade represents the ‘true Nuncia ’ from New Zealand, a large diversification with 58 named taxa (34 species with 34 subspecies), divided into three subgenera ( Nuncia , Corinuncia , Micronuncia ). Based on results from Baker et al. (2020 b), who included 62 New Zealand Nuncia specimens covering much of the specific diversity of the genus, monophyly of these subgenera seems unlikely, and some species with multiple subspecies may be paraphyletic. This genus would greatly benefit from a taxonomic revision, and initial steps have been taken with the recent redescription of the type (sub)species Nuncia obesa obesa (Simon, 1889) ( Porto and Pérez-González 2019) and the molecular work of Baker et al. (2020 b). The unsampled genera Neonuncia Roewer, 1915 and Psalenoba Roewer, 1931 most likely fall into this lineage. Neonuncia was differentiated from Nuncia based only on tarsal segment count of leg I ( Roewer 1914), but Forster (1954) found additional characters separating the two genera. Neonuncia are found either in mainland New Zealand or across multiple islands surrounding New Zealand. Psalenoba is a monotypic New Zealand endemic. Forster (1954) states that examination of this species will show it is placed within Nuncia , perhaps identical to a species described in his work, but the original description and figures are insufficient and the types were unavailable to him. The checklist of Kury et al. (2014) includes the genus Metanuncia Roewer, 1915 with two species, but both species were synonymised into Nuncia by Forster (1954).

Subclade E3. This lineage includes only a single species, Americobunus ringueleti Muñoz Cuevas, 1972 . The monotypic Americobunus is one of two triaenobunines from South America, the other being the distantly related Araucanobunus . Muñoz Cuevas (1972) stated that Americobunus shows similarities to the New Zealand genus Pristobunus Roewer, 1931 largely in somatic morphology (the armature of the body and legs, and tarsal segment count), but also in male genitalic morphology. In a broad sense, this hypothesis is correct as Americobunus is more closely related to Pristobunus (a member of subclade E5) than it is to any other South American taxa.

Subclade E4. This subclade includes a group of taxa from eastern Australia, ranging from Tasmania north to Queensland. The Australian genus Triaenobunus Sørensen, 1886 is paraphyletic. This genus is largely diagnosed by the structure of the eye mound, which is elongate and anteriorly directed with lateral spines. There is uncertainty in the placement of cf. Triaenobunus NHMUC :21B: in the IQTREE analysis it is recovered as sister group to subclade E5 with low support, the BEAST analyses placed it with T. armstrongi and Heteronuncia , and the SVDQuartets places it as sister group to T. armstrongi whereas Heteronuncia is placed as sister group to E3 + E4 + E5. The uncertainty with cf. Triaenobunus and Heteronuncia is likely because they are historical museum specimens with the associated DNA degradation ( Derkarabetian et al. 2019). Our preferred hypothesis consists of two lineages (as reflected in the BEAST analysis). The first lineage includes T. armstrongi Forster, 1955 from New South Wales, cf. Triaenobunus from Victoria, and Heteronuncia robusta Roewer, 1920 , a large species from northern Queensland. The second lineage corresponds to T. asper Hickman, 1958 and T. pectinatus Pocock, 1902 , both of which are from Tasmania. Triaenobunus was also found to be non-monophyletic in Baker et al. (2020 b), although nodal support for relevant nodes was low. It is possible that the samples we sequenced are representative of two groups of Triaenobunus : the lineage including T. armstrongi may represent a mainland Australian group of taxa largely described by Forster (1955) distributed from Victoria to Queensland, whereas T. asper and T. pectinatus represent the eight species from Tasmania. The unsampled genus Dipristes Roewer, 1931 with one species, D. serripus Roewer, 1931 , is certainly related to Triaenobunus , and was originally separated based on the number of lateral spines on the eye mound and tarsal segment count. When originally described, these diagnostic characters were distinct between Dipristes and the Triaenobunus species known at the time. However, since the description of additional Triaenobunus , the diagnostic characters of Dipristes now fall within the variation seen in Triaenobunus , probably necessitating synonymy. We save formal synonymy until a more detailed analysis of Triaenobunus can be undertaken, but we hypothesise that it will be closely related to the mainland Australia clade. The type species of T. bicarinatus Sørensen, 1886 is likely associated with the mainland Australian group as well. Clearly, Triaenobunus needs revision.

This subclade also includes the Tasmanian genus Nucina Hickman, 1958 , the genus Cluniella Forster, 1955 , which has an extremely restricted distribution in southern Queensland, and the more widespread ‘ Hickmanoxyomma complex’. The three species of Cluniella , each with very restricted but overlapping distributions, are particularly interesting because of their extreme hypertrophy of male genitalia ( Hunt and Maury 1993). The ‘ Hickmanoxyomma complex’ is a group of closely related and rapidly diverged genera largely found in Tasmania and south-eastern mainland Australia, including the genera: Hickmanoxyomma Hunt, 1990 , Paranuncia Roewer, 1915 , Odontonuncia Hickman, 1958 , Holonuncia Forster, 1955 , and an indeterminate sample from the Otway Ranges in Victoria (cf. Paranuncia NHMUC :Aus025b). Hunt (1990) stated that Hickmanoxyomma is very similar to both Odontonuncia and an undescribed genus from Victoria (which may correspond to our ‘cf. Paranuncia NHMUC :Aus025b’), and that these share similar genitalic morphology with Paranuncia , Holonuncia and Equitius . With the exception of Equitius (Clade A), our phylogeny agrees with Hunt’ s hypotheses. Notably, the genus Hickmanoxyomma is diphyletic. This genus is restricted to Tasmania and includes seven species, six of which are caveobligate ( Hunt 1990). Hunt (1990) split this genus into two species groups: the cavaticum and tasmanicum species groups. We recover H. tasmanicum ( Roewer, 1915) , the only surface species, as sister group to the two species of Paranuncia (Tasmania and Victoria), whereas H. cavaticum ( Hickman, 1958) is sister species to the monotypic Odontonuncia (Tasmania) . Complete species-level sampling will be needed to determine whether the species groups of Hunt (1990) are reciprocally monophyletic, or if the division corresponds to habitat (cave versus surface). The unsampled monotypic Stylonuncia Hickman, 1958 most likely falls within this lineage. Stylonuncia spinosa Hickman, 1958 was considered to be closely related to Nucina by Hickman (1958), differing in the eye mound and scutal spines. Hunt (1996) recovered Stylonuncia in a group with Nucina and the ‘ Hickmanoxyomma complex’ genera.

Subclade E5. This clade is found in Tasmania, New Zealand, and New Caledonia. Based on scutal patterns and genitalia, Forster (1954) stated that the New Zealand genus Cenefia Roewer, 1931 is related to Pristobunus , also from New Zealand, and Triaenobunus from Australia. Likewise, Forster (1954) compared Pristobunus to Triaenobunus and the unsampled genus Dipristes , largely because of similar eye mound structure. Given this, it is not surprising that Cenefia and Pristobunus are sister taxa, and they are early diverging in E5, as that eye mound may be plesiomorphic for clades E4 and E5. The unsampled monotypic Muscicola Forster, 1954 , a greenpigmented arboreal species known only from Fiordland, New Zealand, was considered to be related to Pristobunus by Forster (1954) because it shares similar somatic and genitalic morphology. As such, it is likely related to Pristobunus . In the BEAST analysis the Cenefia + Pristobunus clade is sister group to E4, whereas the SVDQuartets analysis placed it within a Tasmanian group in subclade E5, although with very weak support. Ultimately, this has little effect on our discussion, including the plesiomorphic nature of the eye mound.

Clade E5 includes most of the endemic genus-level diversity of Tasmania, which constitute a well-supported subclade. This clade was largely recovered in the morphological phylogenetic analyses of Hunt (1996), except that he included Triaenobunus , and was supported by two synapomorphies: sternum shape (essentially the Triaenobuninae type) and the ventral plate of the penis each with 2 – 3 superior setae. Similarly, internal relationships of this group largely agree with Hunt (1996) based on morphology. The group that includes Mestonia Hickman, 1958 , Allobunus Hickman, 1958 , Chrestobunus Roewer, 1915 , and Thelbunus Hickman, 1958 shares a synapomorphy of three superior setae on each ventral plate. Phoxobunus Hickman, 1958 is recovered as sister group to a clade containing Phanerobunus Roewer, 1915 , Glyptobunus Roewer, 1915 , Tasmanobunus Hickman, 1958 , Miobunus Roewer, 1915 , and Rhynchobunus Hickman, 1958 . This latter group has a synapomorphy of the penis stylus subdistally with a mediodistal spine. Several unsampled Tasmanian genera likely fall into this group. As recovered in Hunt (1996), the monotypic Chilobunus Hickman, 1958 is likely in the clade near Mestonia and Thelbunus , and the monotypic Eubunus Hickman, 1958 is likely in the clade with Phanerobunus and Glyptobunus . Tasmanobunus as a genus was synonymised with Miobunus , including the type species, T. constans Hickman, 1958 , synonymised with the type species of Miobunus , M. thoracicus Roewer, 1915 by Hunt (1995). This synonymy is reflected in the catalogue of Kury et al. (2014). However, Hunt (1995) notes that Tasmanobunus parvus Hickman, 1958 ‘does not belong in Miobunus ’, and in our analyses it is not sister to Miobunus thoracicus . In the same study, Hunt also notes that Miobunus levis Hickman, 1958 , unsampled in our study, does not belong in Miobunus . In our checklist we consider these incertae sedis and label them as ‘ Miobunus ’ parvus and ‘ M.’ levis until more detailed work can be completed including all relevant taxa. Regardless of name, both species fall within this group, most likely allied with Tasmanobunus , Miobunus and Rhynchobunus . The unsampled genus Tasmanonuncia Hickman, 1958 is likely in the group with Rhynchobunus and Tasmanobunus ; it was recovered as sister group to Rhynchobunus in Hunt (1996) and the genitalia drawn in Hunt and Maury (1993) is similar to those of Tasmanobunus (see Hickman 1958).

Finally, E5 includes a third subclade consisting of generally large-bodied taxa characterised by tuberculate or heavily spined bodies from New Zealand and New Caledonia. Sorensenella and Karamea , two taxa included in the subfamily Sorensenellinae , share very similar genitalia ( Forster 1954), and have been treated in detail, including UCE work, elsewhere ( Baker 2020 ). The unsampled monotypic genus Prasmiola Forster, 1954 is likely the sister group to Prasma Roewer, 1931 , considered closely related by Forster (1954) but differing in tarsal segment counts. Triregia Forster, 1948 , only recorded from the North Island of New Zealand, was found as the sister group to the New Caledonian genera Diaenobunus Roewer, 1915 and Triconobunus Roewer, 1915 . These genera are very similar morphologically, being densely covered in spines, with the New Caledonian taxa differentiated only by the number of spines on the eye mound ( Roewer 1914, 1915). More thorough sampling of Triregia may show this genus to be paraphyletic with respect to the New Caledonian genera and that the New Caledonian genera may in fact constitute two independent colonisations of the island, as suggested, albeit with low support, in Baker et al. (2020 b), perhaps necessitating synonymy of some of these genera.

Taxa of uncertain affinity

Two unsampled genera cannot be placed with certainty. First, Brasiloctis Mello-Leitão, 1938 with a single species, B. bucki Mello-Leitão, 1938 , is known from a single site in south-east Brazil. Based on the original description and the single drawing provided, this species has a Triaenobunus -like appearance, covered in spines with a forward-projecting eye mound with lateral spines. As such, it could be closely related to the South American Americobunus (subclade E3), another spiny – tuberculate-bodied species with forward-projecting eyemound, which is the sister group to clade E4 + E5, where Triaenobunus is early diverging in E4. Conversely, based on biogeography, all South American taxa (except the caveobligate Picunchenops ) found east of the Andes (i.e. Ceratomontia ) fall within Clade B.

Second, the monotypic genus Lawrencella Strand, 1932 , which is the second of two Sorenesenellinae in South Africa (with Speleomontia ), is also difficult to place. Lawrence (1931) states that Lawrencella inermis ( Lawrence, 1931) , then described as Roeweria inermis , resembles Mensamontia in tarsal segment count. Based on these similarities, and the results of the IQ-TREE analyses, we would hypothesise that Lawrencella is included in the Speleomontia + Mensamontia lineage (subclade D1), the three of which are restricted to the Western Cape Province of South Africa. However, the BEAST and SVDQuartets analyses do not recover Speleomontia + Mensamontia , instead placing Mensamontia in Clade C. As such, the placement of Lawrencella , and Mensamontia , remains uncertain.

Figures

Fig. 1. Photographs of live Triaenonychoidea. (A) Synthetonychiidae: Synthetonychia oliveae, MCZ:IZ:144638. (B) Lomanellidae: Lomanella sp., MCZ:IZ:152652. (C) Buemarinoidae: Fumontana deprehendor. (D–O): Triaenonychidae. (D) Hendea myersi cavernicola [Clade A]. (E) Austromontia sp. [Clade B], MCZ:IZ:49523. (F) Triaenonyx chilensis [Clade C], MCZ:IZ:138132. (G) Larifuga sp. [Clade D1], MCZ:IZ:132879. (H) Yatala aspera [Clade D4], MCZ:IZ:152561. (I) Calliuncus sp. [Clade E1], MCZ:IZ:152607. (J) ‘new genus B Australia’ [Clade D5], MCZ:IZ:152679. (K) Nuncia sp. [Clade E2], MCZ:IZ:133374. (L) Triaenobunus asper [Clade E4]. (M) Glyptobunus ornatus [Clade E5]. (N) Phanerobunus saxatilis [Clade E5]. (O) Diaenobunus armatus [Clade E5], MCZ:IZ:151609. Photographs copyright of Gonzalo Giribet (A, E–G, K, O), Marshal Hedin (C, L–N), Shahan Derkarabetian (B, H–J). (D) copyright and courtesy of Erin Powell.