Sandokanid phylogeny based on eight molecular markers—The evolution of a southeast Asian endemic family of Laniatores (Arachnida, Opiliones)

Historical biogeography of a neglected family of armoured harvestmen (Opiliones : Laniatores : Icaleptidae) with the first record and a new genus for tropical Mesoamerica

Among Opiliones (Arachnida), there are many taxa either with no familial assignment or erroneously located in their current family. This is the case of Ethobunus pilosus, formerly in Phalangodidae and before this work in Zalmoxidae. To assess the phylogenetic position of this taxon, we started with a revision of the male genitalia; followed by the inclusion of three molecular markers: nuclear 28S and 18S, and mitochondrial protein-encoding cytochrome c oxidase subunit I (COI) from E. pilosus in the previously published phylogenies of the Samooidea + Zalmoxoidea clade. The results revealed that E. pilosus is a derived lineage within the family Icaleptidae, thus it is transferred from Zalmoxidae, and the new name Trypophobica gen. nov. is proposed to accommodate it, with the new combination Trypophobica pilosa comb. nov. With its inclusion in Icaleptidae, and the description of Trypophobica llama sp. nov., the current diagnosis of the family needs updating, and further morphological characters should be considered as putative synapomorphies. In addition, the reconstruction of the ancestral ranges of Icaleptidae suggests a mid-Cretaceous origin c. 104 Ma in South America, with a subsequent colonisation to north Mesoamerica c. 80 Ma.

A polyvalent and universal tool for genomic studies in gastropod molluscs (Heterobranchia)

Molluscs are the second most diverse animal phylum and heterobranch gastropods present ~ 44,000 species. These comprise fascinating creatures with huge morphological and ecological disparity. Such great diversity comes with even larger phylogenetic uncertainty and many taxa have been largely neglected in molecular assessments. Genomic tools have provided resolution to deep cladogenic events but generating large numbers of transcriptomes/genomes is expensive and usually requires fresh material. Here we leverage a target enrichment approach to design and synthesize a probe set based on available genomes and transcriptomes across Heterobranchia. Our probe set contains 57,606 70mer baits and targets a total of 2,259 ultra-conserved elements (UCEs). Post-sequencing capture efficiency was tested against 31 marine heterobranchs from major groups, including Acochlidia, Acteonoidea, Aplysiida, Cephalaspidea, Pleurobranchida, Pteropoda, Runcinida, Sacoglossa, and Umbraculida. The combined Trinity and Velvet assemblies recovered up to 2,211 UCEs in Tectipleura, up to 1,978 in Nudipleura, and up to 1,927 in Acteonoidea, the latter two being the most distantly related taxa to our core study group. Total alignment length was 525,599 bp and contained 52% informative sites and 21% missing data. Maximum-likelihood and Bayesian inference approaches recovered the monophyly of all orders tested as well as the larger clades Nudipleura, Panpulmonata, and Euopisthobranchia. The successful enrichment of diversely preserved material and DNA concentrations demonstrate the polyvalent nature of UCEs, and the universality of the probe set designed. We believe this probe set will enable multiple, interesting lines of research, that will benefit from an inexpensive and largely informative tool that will, additionally, benefit from the access to museum collections to gather genomic data.

Evolution of a sensory cluster on the legs of Opiliones (Arachnida) informs multi-level phylogenetic relationships

Phylogenetic relationships in Opiliones (Arachnida) at the suborder level have greatly stabilized in recent years, largely due to advances in molecular systematics. Nonetheless, identifying morphological characters in the context of well-resolved phylogenies is essential for testing new systematic hypotheses and establishing diagnostic markers. Here, we investigate with SEM a promising character system across Opiliones: the sensilla on the distalmost article of legs I and II. We identified four discrete characters and scored species of nearly all families of Laniatores (28 families, 44 species), three Dyspnoi, two Eupnoi and two Cyphophthalmi. Using a phylogenetic backbone compiled from recent and ongoing phylogenomic studies, we trace the evolution of these sensilla using ancestral state reconstruction. We discover a widespread occurrence of three sensilla (a pair of sensilla basiconica and one hooded sensillum) on the anterior legs of all families of Laniatores studied, and that comparable structures occur in the other suborders of Opiliones. Our analysis shows that this sensory field provides diagnostic information at different levels of phylogenetic relationships. We discuss the implications of the widespread occurrence of these sensilla in Opiliones, which have recently been hypothesized as hygro-/thermoreceptors and their putative homology with tarsal organs in Arachnida.

The anatomy of an unstable node: a Levantine relict precipitates phylogenomic dissolution of higher-level relationships of the armoured harvestmen (Arachnida: Opiliones: Laniatores)

After tumultuous revisions to the family-level systematics of Laniatores (the armored harvestmen), the basally branching family Phalangodidae presently bears a disjunct and irregular distribution, attributed to the fragmentation of Pangea. One of the curious lineages assigned to Phalangodidae is the monotypic Israeli genus Haasus, the only Laniatores species that occurs in Israel, and whose presence in the Levant has been inferred to result from biogeographic connectivity with Eurasia. Recent surveys of Israeli caves have also yielded a new troglobitic morphospecies of Haasus. Here, we describe this new species as Haasus naasane sp. nov. So as to test the biogeographic affinity of Haasus, we sequenced DNA from both species and RNA from Haasus naasane sp. nov., to assess their phylogenetic placement. Our results showed that the new species is clearly closely related to Haasus judaeus, but Haasus itself is unambiguously nested within the largely Afrotropical family Pyramidopidae. In addition, the Japanese ‘phalangodid’ Proscotolemon sauteri was recovered as nested within the Southeast Asian family Petrobunidae. Phylogenomic placement of Haasus naasane sp. nov. in a 1550-locus matrix indicates that Pyramidopidae has an unstable position in the tree of Laniatores, with alternative partitioning of the matrix recovering high nodal support for mutually exclusive tree topologies. Exploration of phylogenetic signal showed the cause of this instability to be a considerable conflict between partitions, suggesting that the basal phylogeny of Laniatores may not yet be stable to addition of taxa. We transfer Haasus to Pyramidopidae (new familial assignment). Additionally, we transfer Proscotolemon to the family Petrobunidae (new familial assignment). Future studies on basal Laniatores phylogeny should emphasise the investigation of small-bodied and obscure groups that superficially resemble Phalangodidae.

A new species of Tithaeidae (Arachnida: Opiliones: Laniatores) from Mindanao reveals contemporaneous colonisation of the Philippines by Sunda Shelf opiliofauna

The Philippine archipelago harbours a remarkable diversity of harvestmen, with respect to both taxonomy and complexity of biogeographic origins. Among the armoured harvestmen (suborder Laniatores), six families of distantly related groups occur in this archipelago. Here, we describe a new species of the family Tithaeidae, Tithaeus odysseus sp. nov., discovered during a collecting campaign on the island of Mindanao. The description of this species expands the known distribution of the family and demonstrates another exception to the zoogeographic boundary known as Huxley’s Line which putatively separates the biota of the Philippines (excluding the Palawan island group) from the Sunda Shelf biota. Given the coincident distributions of Tithaeidae and the mite harvestman family Stylocellidae (Cyphophthalmi), a group renowned for its poor dispersal ability, we inferred phylogenetic relationships and divergence times of the Philippines lineages of both families by using a comprehensive molecular dating analysis of all Opiliones. The internal phylogeny of Tithaeidae mirrored the biogeography of Philippine Stylocellidae, showing a close affinity between the Philippine and Bornean species. Molecular dating showed contemporaneous colonisation of Mindanao by both families in the Cretaceous. We infer these patterns to reflect faunal connections between the southern Philippines and Borneo via the Zamboanga Peninsula. To render the genus Tithaeus monophyletic, we synonymise Metatithaeus with Tithaeus (new synonymy).

The sensory equipment of a sandokanid: An extreme case of tarsal reduction in harvestmen (Arachnida, Opiliones, Laniatores)

The study of sensory structures has the potential to provide insights into the natural history and evolution of animals. The sensory structures of arachnids are usually concentrated on the pedipalps (the tritocerebral appendages) or on the distal podomere (tarsus) of the anterior walking legs, the latter being the case for armored harvestmen (Opiliones, Laniatores). Therefore, modifications of the tarsus could have direct impacts on the sensory equipment of these animals. Using scanning electron microscopy, we investigated the sensory equipment in an extreme case of reduction in tarsal articles in the harvestman Sandokan truncatus (Sandokanidae), which bears a single tarsomere in all legs, and the potential consequences of this reduction. Additionally, we review the literature on the natural history of the family Sandokanidae. Tarsomeres of all legs are equipped with gustatory sensilla, mechanoreceptors, and a pore organ, but wall-pored olfactory sensilla are restricted to tarsi I and II. Tarsi II present a higher density of olfactory sensilla and also putative campaniform sensilla (strain detectors), which indicates a special sensory function of this pair of legs. Other podomeres are covered with shelled sensilla, a probable chemoreceptor previously unreported in Opiliones. Overall, S. truncatus has types of sensilla largely comparable to harvestmen with longer and subdivided tarsi. However, S. truncatus also exhibits extra-tarsal sensory fields of sensilla basiconica (putative thermo-/hygroreceptors) in previously undescribed sites, and the unique pore organs. Our results establish a basis for further research investigating the natural history, as well as the evolutionary correlations and mechanistic causes of the tarsal reduction in this enigmatic lineage.

Expression and function of spineless orthologs correlate with distal deutocerebral appendage morphology across Arthropoda

The deutocerebral (second) head segment is putatively homologous across Arthropoda, in spite of remarkable disparity of form and function of deutocerebral appendages. In Mandibulata this segment bears a pair of sensory antennae, whereas in Chelicerata the same segment bears a pair of feeding appendages called chelicerae. Part of the evidence for the homology of deutocerebral appendages is the conserved function of homothorax (hth), which has been shown to specify antennal or cheliceral fate in the absence of Hox signaling, in both mandibulate and chelicerate exemplars. However, the genetic basis for the morphological disparity of antenna and chelicera is not understood. To test whether downstream targets of hth have diverged in a lineage-specific manner, we examined the evolution of the function and expression of spineless (ss), which in two holometabolous insects is known to act as a hth target and distal antennal determinant. Toward expanding phylogenetic representation of gene expression data, here we show that strong expression of ss is observed in developing antennae of a hemimetabolous insect, a centipede, and an amphipod crustacean. By contrast, ss orthologs are not expressed throughout the cheliceral limb buds of spiders or harvestmen during developmental stages when appendage fate is specified. RNA interference-mediated knockdown of ss in Oncopeltus fasciatus, which bears a simple plesiomorphic antenna, resulted in homeotic distal antenna-to-leg transformation, comparable to data from holometabolous insect counterparts. Knockdown of hth in Oncopeltus fasciatus abrogated ss expression, suggesting conservation of upstream regulation. These data suggest that ss may be a flagellar (distal antennal) determinant more broadly, and that this function was acquired at the base of Mandibulata.

The Opiliones tree of life: shedding light on harvestmen relationships through transcriptomics

Opiliones are iconic arachnids with a Palaeozoic origin and a diversity that reflects ancient biogeographic patterns dating back at least to the times of Pangea. Owing to interest in harvestman diversity, evolution and biogeography, their relationships have been thoroughly studied using morphology and PCR-based Sanger approaches to infer their systematic relationships. More recently, two studies utilized transcriptomics-based phylogenomics to explore their basal relationships and diversification, but sampling was limiting for understanding deep evolutionary patterns, as they lacked good taxon representation at the family level. Here, we analysed a set of the 14 existing transcriptomes with 40 additional ones generated for this study, representing approximately 80% of the extant familial diversity in Opiliones. Our phylogenetic analyses, including a set of data matrices with different gene occupancy and evolutionary rates, and using a multitude of methods correcting for a diversity of factors affecting phylogenomic data matrices, provide a robust and stable Opiliones tree of life, where most families and higher taxa are precisely placed. Our dating analyses using alternative calibration points, methods and analytical parameters provide well-resolved old divergences, consistent with ancient regionalization in Pangea in some groups, and Pangean vicariance in others. The integration of state-of-the-art molecular techniques and analyses, together with the broadest taxonomic sampling to date presented in a phylogenomic study of harvestmen, provide new insights into harvestmen interrelationships, as well as an overview of the general biogeographic patterns of this ancient arthropod group.

Total evidence phylogeny of the North American harvestman family Stygnopsidae (Opiliones : Laniatores : Grassatores) reveals hidden diversity

Systematic relationships among Laniatores have received considerable attention during the past few years. Many significant taxonomic changes have been proposed, particularly in the superfamily Gonyleptoidea. As part of this superfamily, the basalmost Stygnopsidae is the least known family. In order to propose the first total evidence phylogeny of the family, we produced four datasets: three molecular markers – partial nuclear 28S, mitochondrial ribosomal 16S, mitochondrial protein-encoding cytochrome c oxidase subunit I; and 72 morphological characters. With these data, we performed three different phylogenetic analyses: (1) Bayesian Inference with molecular data, and (2) Bayesian Inference and (3) Maximum Likelihood using combined data. Our results are congruent: a monophyletic Stygnopsidae subdivided into two major clades: Stygnopsinae and Karosinae, subfam. nov. The following genera are redefined: Stygnopsis, Hoplobunus and Serrobunus stat. rev. The following taxa are described: Iztlina venefica, gen. nov., sp. nov. and Tonalteca, gen. nov. Additionally, the following changes are proposed: Serrobunus queretarius (Šilhavý, 1974), comb. nov., Stygnopsis apoalensis (Goodnight & Goodnight, 1973), comb. nov., Stygnopsis mexicana (Roewer, 1915), comb. nov., Stygnopsis oaxacensis (Goodnight & Goodnight, 1973), comb. nov., and Tonalteca spinooculorum (Goodnight & Goodnight, 1973), comb. nov. We also discuss the status of the genera Isaeus stat. rev. and Mexotroglinus. Finally, we discuss the evolution of male genitalia and convergence of selected homoplastic diagnostic characters.

A multilocus phylogeny of Podoctidae (Arachnida, Opiliones, Laniatores) and parametric shape analysis reveal the disutility of subfamilial nomenclature in armored harvestman systematics

The taxonomy and systematics of the armored harvestmen (suborder Laniatores) are based on various sets of morphological characters pertaining to shape, armature, pedipalpal setation, and the number of articles of the walking leg tarsi. Few studies have tested the validity of these historical character systems in a comprehensive way, with reference to an independent data class, i.e., molecular sequence data. We examined as a test case the systematics of Podoctidae, a family distributed throughout the Indo-Pacific. We tested the validity of the three subfamilies of Podoctidae using a five-locus phylogeny, and examined the evolution of dorsal shape as a proxy for taxonomic utility, using parametric shape analysis. Here we show that two of the three subfamilies, Ibaloniinae and Podoctinae, are non-monophyletic, with the third subfamily, Erecananinae, recovered as non-monophyletic in a subset of analyses. Various genera were also recovered as non-monophyletic. As first steps toward revision of Podoctidae, the subfamilies Erecananinae Roewer, 1912 and Ibaloniinae Roewer, 1912 are synonymized with Podoctinae Roewer, 1912 new synonymies, thereby abolishing unsubstantiated subfamilial divisions within Podoctidae. We once again synonymize the genus Paralomanius Goodnight & Goodnight, 1948 with Lomanius Roewer, 1923 revalidated. We additionally show that eggs carried on the legs of male Podoctidae are not conspecific to the males, falsifying the hypothesis of paternal care in this group.

Evolutionary biology of harvestmen (Arachnida, Opiliones)

Opiliones are one of the largest arachnid orders, with more than 6,500 species in 50 families. Many of these families have been erected or reorganized in the last few years since the publication of The Biology of Opiliones. Recent years have also seen an explosion in phylogenetic work on Opiliones, as well as in studies using Opiliones as test cases to address biogeographic and evolutionary questions more broadly. Accelerated activity in the study of Opiliones evolution has been facilitated by the discovery of several key fossils, including the oldest known Opiliones fossil, which represents a new, extinct suborder. Study of the group's biology has also benefited from rapid accrual of genomic resources, particularly with respect to transcriptomes and functional genetic tools. The rapid emergence and utility of Phalangium opilio as a model for evolutionary developmental biology of arthropods serve as demonstrative evidence of a new area of study in Opiliones biology, made possible through transcriptomic data.

A Paleozoic stem group to mite harvestmen revealed through integration of phylogenetics and development

Successfully placing fossils in phylogenies is integral to understanding the tree of life. Crown-group Paleozoic members of the arachnid order Opiliones are indicative of ancient origins and one of the earliest arthropod terrestrialization events [1, 2]. Opiliones epitomize morphological stasis, and all known fossils have been placed within the four extant suborders [3-5]. Here we report a Carboniferous harvestman species, Hastocularis argusgen. nov., sp. nov., reconstructed with microtomography (microCT). Phylogenetic analysis recovers this species, and the Devonian Eophalangium sheari, as members of an extinct harvestman clade. We establish the suborder Tetrophthalmi subordo nov., which bore four eyes, to accommodate H. argus and E. sheari, the latter previously considered to be a phalangid [6-9]. Furthermore, embryonic gene expression in the extant species Phalangium opilio demonstrates vestiges of lateral eye tubercles. These lateral eyes are lost in all crown-group Phalangida, but are observed in both our fossil and outgroup chelicerate orders. These data independently corroborate the diagnosis of two eye pairs in the fossil and demonstrate retention of eyes of separate evolutionary origins in modern harvestmen [10-12]. The discovery of Tetrophthalmi alters molecular divergence time estimates, supporting Carboniferous rather than Devonian diversification for extant suborders and directly impacting inferences of terrestrialization history and biogeography. Multidisciplinary approaches integrating fossil and neontological data increase confidence in phylogenies and elucidate evolutionary history.

A molecular phylogenetic approach to the New Zealand species of Enantiobuninae (Opiliones : Eupnoi : Neopilionidae)

Members of the New Zealand Enantiobuninae constitute some of the most charismatic soil arthropods of the archipelago, and a striking example of sexual dimorphism, with nondescript females but colourful males boasting exaggerated chelicerae many times longer than their bodies. The genera Forsteropsalis and Pantopsalis recently underwent revision, but many questions remained about the validity of species designations owing to historical issues of characters of dubious taxonomic value, female specimens designated as holotypes despite the males holding all the diagnostic characters, and the suspected presence of more than one male form within some species. We present the first phylogeny based on molecular data for the New Zealand species in the genera Forsteropsalis, Pantopsalis and Mangatangi, and comment on the taxonomic implications of our results, including the diagnostic viability of important morphological characters. Our analyses reject the monophyly of Neopilionidae and Forsteropsalis, but support the monophyly of Pantopsalis. Finally, we comment on the taxonomic implications of the results, including the diagnostic validity of morphological characters traditionally used on the groups.

Into the deep: a phylogenetic approach to the bivalve subclass Protobranchia

A molecular phylogeny of Protobranchia, the subclass of bivalve mollusks sister to the remaining Bivalvia, has long proven elusive, because many constituent lineages are deep-sea endemics, which creates methodological challenges for collecting and preserving genetic material. We obtained 74 representatives of all 12 extant protobranch families and investigated the internal phylogeny of this group using sequence data from five molecular loci (16S rRNA, 18S rRNA, 28S rRNA, cytochrome c oxidase subunit I, and histone H3). Model-based and dynamic homology parsimony approaches to phylogenetic reconstruction unanimously supported four major clades of Protobranchia, irrespective of treatment of hypervariable regions in the nuclear ribosomal genes 18S rRNA and 28S rRNA. These four clades correspond to the superfamilies Nuculoidea (excluding Sareptidae), Nuculanoidea (including Sareptidae), Solemyoidea, and Manzanelloidea. Salient aspects of the phylogeny include (1) support for the placement of the family Sareptidae with Nuculanoidea; (2) the non-monophyly of the order Solemyida (Solemyidae+Nucinellidae); (3) and the non-monophyly of most nuculoid and nuculanoid genera and families. In light of this first family-level phylogeny of Protobranchia, we present a revised classification of the group. Estimation of divergence times in concert with analyses of diversification rates demonstrate the signature of the end-Permian mass extinction in the phylogeny of extant protobranchs.

Elongation factor-1α, a putative single-copy nuclear gene, has divergent sets of paralogs in an arachnid

Identification of paralogy in candidate nuclear loci is an important prerequisite in phylogenetics and statistical phylogeography, but one that is often overlooked. One marker commonly assumed to be a single-copy gene and claimed to harbor great utility for inferring recent divergences is elongation factor-1α (EF-1α). To test this hypothesis, we systematically cloned EF-1α in three disjunct populations of the harvestman Metasiro americanus. Here we show that EF-1α has a large number of paralogs in this species. The paralogs do not evolve in a concerted manner, and the paralogs diverged prior to the population divergence. Moreover, the paralogs of M. americanus are not comparable to the highly divergent EF-1α paralogs found in bees and spiders, which are easily recognized and separated through the use of specific primers. We demonstrate statistically that our detection of paralogs cannot be attributed to amplification error. The presence of EF-1α paralogs in M. americanus prevents its use in statistical phylogeography, and the presence of out-paralogs argues against its use in phylogenetic inference among recently diverged clades. These data contradict the common assumption that EF-1α is for most or all taxa a single-copy gene, or that it has a small number of paralogs that are homogenized through gene conversion, unequal crossing over, or other processes.

Application of 16s rDNA and cytochrome b ribosomal markers in studies of lineage and fish populations structure of aquatic species

The most economically important form of aquaculture is fish farming, which is an industry that accounts for an ever increasing share of world fishery production. Molecular markers can be used to enhance the productivity of the aquaculture and fish industries to meet the increasing demand. Molecular markers can be identified via a DNA test regardless of the developmental stage, age or environmental challenges experienced by the organism. The application of 16s and cytochrome b markers has enabled rapid progress in investigations of genetic variability and inbreeding, parentage assignments, species and strain identification and the construction of high resolution genetic linkage maps for aquaculture fisheries. In this review, the advantages of principles and potential power tools of 16s and cytochrome b markers are discussed. Main findings in term of trend, aspects and debates on the reviewed issue made from the model of aquatic species for the benefit of aquaculture genomics and aquaculture genetics research are discussed. The concepts in this review are illustrated with various research examples and results that relate theory to reality and provide a strong review of the current status of these biotechnology topics.

The evolutionary and biogeographic history of the armoured harvestmen – Laniatores phylogeny based on ten molecular markers, with the description of two new families of Opiliones (Arachnida)

We investigated the internal phylogeny of Laniatores, the most diverse suborder of Opiliones, using sequence data from 10 molecular loci: 12S rRNA, 16S rRNA, 18S rRNA, 28S rRNA, cytochrome c oxidase subunit I (COI), cytochrome b, elongation factor-1α, histones H3 and H4, and U2 snRNA. Exemplars of all previously described families of Laniatores were included, in addition to two families – Petrobunidae, fam. nov. and Tithaeidae, fam. nov. – that we erect herein. Data analyses were based on maximum likelihood and Bayesian approaches on static alignments, and included phylogenetic tree estimation, molecular dating, and biogeographic analysis of ancestral area reconstruction. The results obtained include the monophyly of Laniatores and the infraorder Grassatores – the focus of this study – as well as support for numerous interfamilial relationships. The two new families described cluster with other South-east Asian families (Podoctidae and Epedanidae). Diversification of Laniatores is estimated at ~348 Mya, and origin of most Grassatores superfamilies occurs in a ~25 million year span of time immediately after the end-Permian mass extinction (254 Mya). Ancestral range reconstruction of the clade (Samooidea + Zalmoxoidea) suggests that the ancestral range of Samooidea comprises West Tropical Gondwana (West Africa + Neotropics), whereas that of Zalmoxoidea is exclusively Neotropical. The following additional taxonomic changes are proposed: (1) Remyus is transferred to Phalangodidae, and (2) Escadabiidae and Kimulidae are transferred to Zalmoxoidea.

A new family of Laniatores (Arachnida:Opiliones) from the Afrotropics

Among Opiliones, Afrotropical lineages constitute some of the least studied groups in comparison with those endemic to other biogeographic provinces. Based upon morphological evidence, we erect Pyramidopidae, fam. nov. to distinguish a group of Laniatores from the family Phalangodidae. We review evidence from recent molecular phylogenetic studies that corroborate the independence of Pyramidopidae, fam. nov. from previously described families and support its sister relationship to another largely Afrotropical group, the family Assamiidae. The monotypic genus Maiorerus Rambla, 1993 is transferred to Pyramidopidae, fam. nov. The new family comprises 12 genera geographically restricted to Africa and the adjacent Canary Islands. Interfamilial relationships of the derived Laniatores are discussed in the context of gross and genitalic morphology.

A phylogenetic analysis for the South-east Asian mite harvestman family Stylocellidae (Opiliones:Cyphophthalmi) – a combined analysis using morphometric and molecular data

In an effort to place type specimens lacking molecular data into a phylogenetic framework ahead of a taxonomic revision, we used morphometric data, both alone and in combination with a molecular dataset, to generate phylogenetic hypotheses under the parsimony criterion for 107 members of the South-east Asian mite harvestman family Stylocellidae (Arachnida: Opiliones: Cyphophthalmi). For the morphometric analyses, we used undiscretised characters, analysed for independence and collapsed by principal components analysis (PCA) when dependent. Two challenges not previously encountered in the use of this method were (a) handling terminals with missing data, necessitated by the inclusion of old and damaged type specimens, and (b) controlling for extreme variation in size. Custom scripts for independence analysis were modified to accommodate missing data whereby placeholder numbers were used during PCA for missing measurements. Size was controlled in four ways: choosing characters that avoided misleading size information and were easily scaled; using only locally scaled measurements; adjusting ratios by y-intercepts; and collapsing dependent characters into one. These steps removed enough size information that miniaturised and large species, suspected from molecular and discrete morphological studies to be closely related, were closely placed using morphometric data alone. Both morphometric and combined analyses generated relationships that positioned type specimens in agreement with taxonomic expectations and our knowledge of the family from prior studies. The hypotheses generated here provide new direction in linking molecular analyses with established taxonomy in this large group of South-east Asian arachnids.