skip to main content

Title: Increasing Information Content and Diagnosability in Family-Level Classifications

Higher-level classifications often must account for monotypic taxa representing depauperate evolutionary lineages and lacking synapomorphies of their better-known, well-defined sister clades. In a ranked (Linnean) or unranked (phylogenetic) classification system, discovering such a depauperate taxon does not necessarily invalidate the rank classification of sister clades. Named higher taxa must be monophyletic to be phylogenetically valid. Ranked taxa above the species level should also maximize information content, diagnosability, and utility (e.g., in biodiversity conservation). In spider classification, families are the highest rank that is systematically catalogued, and incertae sedis is not allowed. Consequently, it is important that family-level taxa be well defined and informative. We revisit the classification problem of Orbipurae, an unranked suprafamilial clade containing the spider families Nephilidae, Phonognathidae, and Araneidae sensu stricto. We argue that, to maximize diagnosability, information content, conservation utility, and practical taxonomic considerations, this “splitting” scheme is superior to its recently proposed alternative, which lumps these families together as Araneidae sensu lato. We propose to redefine Araneidae and recognize a monogeneric spider family, Paraplectanoididae fam. nov. to accommodate the depauperate lineage Paraplectanoides. We present new subgenomic data to stabilize Orbipurae topology which also supports our proposed family-level classification. Our example from spiders demonstrates why classifications must be able to accommodate depauperate evolutionary lineages, for example, Paraplectanoides. Finally, although clade age should not be a criterion to determine rank, other things being equal, comparable ages of similarly ranked taxa do benefit comparative biology. [Classification, family rank, phylogenomics, systematics, monophyly, spider phylogeny.]

more » « less
Author(s) / Creator(s):
; ; ; ; ; ; ; ; ; ; ;
Publisher / Repository:
Oxford University Press
Date Published:
Journal Name:
Systematic Biology
Page Range / eLocation ID:
p. 964-971
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. Abstract

    The family Mutillidae (Hymenoptera) is a species‐rich group of aculeate wasps that occur worldwide. The higher‐level classification of the family has historically been controversial due, in part, to the extreme sexual dimorphism exhibited by these insects and their morphological similarity to other wasp taxa that also have apterous females. Modern hypotheses on the internal higher classification of Mutillidae have been exclusively based on morphology and, further, they include Myrmosinae as a mutillid subfamily. In contrast, several molecular‐based family‐level studies of Aculeata recovered Myrmosinae as a nonmutillid taxon. To test the validity of these morphology‐based classifications and the phylogenetic placement of the controversial taxon Myrmosinae, a phylogenomic study of Mutillidae was conducted using ultraconserved elements (UCEs). All currently recognized subfamilies and tribes of Mutillidae were represented in this study using 140 ingroup taxa. The maximum likelihood criterion (ML) and the maximum parsimony criterion (MP) were used to infer the phylogenetic relationships within the family and related taxa using an aligned data set of 238,764 characters; the topologies of these respective analyses were largely congruent. The modern higher classification of Mutillidae, based on morphology, is largely congruent with the phylogenomic results of this study at the subfamily level, whereas the tribal classification is poorly supported. The subfamily Myrmosinae was recovered as sister to Sapygidae in the ML analysis and sister to Sapygidae + Pompilidae in the MP analysis; it is consequently raised to the family level, Myrmosidae,stat.nov.The two constituent tribes of Myrmosidae are raised to the subfamily level, Kudakrumiinae,stat.nov., and Myrmosinae,stat.nov.All four recognized tribes of Mutillinae were found to be non‐monophyletic; three additional mutilline clades were recovered in addition to Ctenotillini, Mutillini, Smicromyrmini, and Trogaspidiini sensu stricto. Three new tribes are erected for members of these clades: Pristomutillini Waldren,trib.nov., Psammothermini Waldren,trib.nov., and Zeugomutillini Waldren,trib.nov.All three recognized tribes of Sphaeropthalminae were found to be non‐monophyletic; six additional sphaeropthalmine clades were recovered in addition to Dasymutillini, Pseudomethocini, and Sphaeropthalmini sensu stricto. The subtribe Ephutina of Mutillinae: Mutillini was found to be polyphyletic, with theEphutagenus‐group recovered within Sphaeropthalminae and theOdontomutillagenus‐group recovered as sister to Myrmillinae + Mutillinae. Consequently, the subtribe Ephutina is transferred from Mutillinae: Mutillini and is raised to a tribe within Sphaeropthalminae, Ephutini,stat.nov.Further, the taxon Odontomutillinae,stat.nov., is raised from a synonym of Ephutina to the subfamily level. The sphaeropthalmine tribe Pseudomethocini was found to be polyphyletic, with the subtribe Euspinoliina recovered as a separate clade in Sphaeropthalminae; consequently, Euspinoliina is raised to a tribe, Euspinoliini,stat.nov., in Sphaeropthalminae. The dasylabrine tribe Apteromutillini was recovered within Dasylabrini and is proposed as a new synonym of Dasylabrinae. Finally, dating analyses were conducted to infer the ages of the Pompiloidea families (Mutillidae, Myrmosidae, Pompilidae, and Sapygidae) and the ages of the Mutillidae subfamilies and tribes.

    more » « less
  2. Portunoidea is a diverse lineage of ecologically and economically important marine crabs comprising 8 families and 14 subfamilies. Closely related portunid subfamilies Caphyrinae and Thalamitinae constitute some of this group’s greatest morphological and taxonomic diversity, and are the only known lineages to include symbiotic taxa. Emergence of symbiosis in decapods remains poorly studied and portunoid crabs provide an interesting, but often overlooked example. Yet the paucity of molecular phylogenetic data available for Portunoidea makes it challenging to investigate the evolution and systematics of the group. Phylogenetic analyses, though limited, suggest that many putative portunoid taxa are para- or polyphyletic. Here I augment existing molecular data—significantly increasing taxon sampling of Caphyrinae, Thalamitinae, and several disparate portunoid lineages—to investigate the phylogenetic origin of symbiosis within Portunoidea and reevaluate higher- and lower-level portunoid classifications. Phylogenetic analyses were carried out on sequences of H3, 28S rRNA, 16S rRNA, and CO1 for up to 168 portunoid taxa; this included, for the first time, molecular data from the genera Atoportunus , Brusinia , Caphyra , Coelocarcinus , Gonioinfradens , Raymanninus , and Thalamonyx . Results support the placement of all symbiotic taxa ( Caphyra , Lissocarcinus , and two Thalamita ) in a single clade derived within the thalamitine genus Thalamita . Caphyrina Paulson, 1875, nom. trans. is recognized here as a subtribe within the subfamily Thalamitinae. Results also support the following taxonomic actions: Cronius is reclassified as a thalamitine genus; Thalamonyx is reestablished as a valid genus; Goniosupradens is raised to the generic rank; and three new genera ( Zygita gen. nov., Thranita gen. nov., and Trierarchus gen. nov.) are described to accommodate some Thalamita s.l. taxa rendered paraphyletic by Caphyrina. A new diagnosis of Thalamitinae is provided. Results also support a more conservative classification of Portunoidea comprising three instead of eight extant families: Geryonidae (Geryonidae + Ovalipidae; new diagnosis provided), Carcinidae (Carcinidae + Pirimelidae + Polybiidae + Thiidae + Coelocarcinus ; new diagnosis provided) and Portunidae. Finally, 16s rRNA data suggests family Brusiniidae might not be a portunoid lineage. 
    more » « less
  3. Abstract

    The infraorder Mygalomorphae is one of the three main lineages of spiders comprising over 3000 nominal species. This ancient group has a worldwide distribution that includes among its ranks large and charismatic taxa such as tarantulas, trapdoor spiders, and highly venomous funnel-web spiders. Based on past molecular studies using Sanger-sequencing approaches, numerous mygalomorph families (e.g., Hexathelidae, Ctenizidae, Cyrtaucheniidae, Dipluridae, and Nemesiidae) have been identified as non-monophyletic. However, these data were unable to sufficiently resolve the higher-level (intra- and interfamilial) relationships such that the necessary changes in classification could be made with confidence. Here, we present a comprehensive phylogenomic treatment of the spider infraorder Mygalomorphae. We employ 472 loci obtained through anchored hybrid enrichment to reconstruct relationships among all the mygalomorph spider families and estimate the timeframe of their diversification. We sampled nearly all currently recognized families, which has allowed us to assess their status, and as a result, propose a new classification scheme. Our generic-level sampling has also provided an evolutionary framework for revisiting questions regarding silk use in mygalomorph spiders. The first such analysis for the group within a strict phylogenetic framework shows that a sheet web is likely the plesiomorphic condition for mygalomorphs, as well as providing insights to the ancestral foraging behavior for all spiders. Our divergence time estimates, concomitant with detailed biogeographic analysis, suggest that both ancient continental-level vicariance and more recent dispersal events have played an important role in shaping modern day distributional patterns. Based on our results, we relimit the generic composition of the Ctenizidae, Cyrtaucheniidae, Dipluridae, and Nemesiidae. We also elevate five subfamilies to family rank: Anamidae (NEW RANK), Euagridae (NEW RANK), Ischnothelidae (NEW RANK), Pycnothelidae (NEW RANK), and Bemmeridae (NEW RANK). Three families Entypesidae (NEW FAMILY), Microhexuridae (NEW FAMILY), and Stasimopidae (NEW FAMILY), and one subfamily Australothelinae (NEW SUBFAMILY) are newly proposed. Such a major rearrangement in classification, recognizing nine newly established family-level rank taxa, is the largest the group has seen in over three decades. [Biogeography; molecular clocks; phylogenomics; spider web foraging; taxonomy.]

    more » « less
  4. Abstract

    We present a phylogenetic analysis of spiders using a dataset of 932 spider species, representing 115 families (only the family Synaphridae is unrepresented), 700 known genera, and additional representatives of 26 unidentified or undescribed genera. Eleven genera of the orders Amblypygi, Palpigradi, Schizomida and Uropygi are included as outgroups. The dataset includes six markers from the mitochondrial (12S, 16S,COI) and nuclear (histone H3, 18S, 28S) genomes, and was analysed by multiple methods, including constrained analyses using a highly supported backbone tree from transcriptomic data. We recover most of the higher‐level structure of the spider tree with good support, including Mesothelae, Opisthothelae, Mygalomorphae and Araneomorphae. Several of our analyses recover Hypochilidae and Filistatidae as sister groups, as suggested by previous transcriptomic analyses. The Synspermiata are robustly supported, and the families Trogloraptoridae and Caponiidae are found as sister to the Dysderoidea. Our results support the Lost Tracheae clade, including Pholcidae, Tetrablemmidae, Diguetidae, Plectreuridae and the family Pacullidae (restored status) separate from Tetrablemmidae. The Scytodoidea include Ochyroceratidae along with Sicariidae, Scytodidae, Drymusidae and Periegopidae; our results are inconclusive about the separation of these last two families. We did not recover monophyletic Austrochiloidea and Leptonetidae, but our data suggest that both groups are more closely related to the Cylindrical Gland Spigot clade rather than to Synspermiata. Palpimanoidea is not recovered by our analyses, but also not strongly contradicted. We find support for Entelegynae and Oecobioidea (Oecobiidae plus Hersiliidae), and ambiguous placement of cribellate orb‐weavers, compatible with their non‐monophyly. Nicodamoidea (Nicodamidae plus Megadictynidae) and Araneoidea composition and relationships are consistent with recent analyses. We did not obtain resolution for the titanoecoids (Titanoecidae and Phyxelididae), but the Retrolateral Tibial Apophysis clade is well supported. Penestomidae, and probably Homalonychidae, are part of Zodarioidea, although the latter family was set apart by recent transcriptomic analyses. Our data support a large group that we call the marronoid clade (including the families Amaurobiidae, Desidae, Dictynidae, Hahniidae, Stiphidiidae, Agelenidae and Toxopidae). The circumscription of most marronoid families is redefined here. Amaurobiidae include the Amaurobiinae and provisionally Macrobuninae. We transfer Malenellinae (Malenella, from Anyphaenidae), Chummidae (Chumma) (new syn.) and Tasmarubriinae (Tasmarubrius,TasmabrochusandTeeatta, from Amphinectidae) to Macrobuninae. Cybaeidae are redefined to includeCalymmaria,Cryphoeca,EthobuellaandWillisius(transferred from Hahniidae), andBlabommaandYorima(transferred from Dictynidae). Cycloctenidae are redefined to includeOrepukia(transferred from Agelenidae) andPakehaandParavoca(transferred from Amaurobiidae). Desidae are redefined to include five subfamilies: Amphinectinae, withAmphinecta,Mamoea,Maniho,ParamamoeaandRangitata(transferred from Amphinectidae); Ischaleinae, withBakalaandManjala(transferred from Amaurobiidae) andIschalea(transferred from Stiphidiidae); Metaltellinae, withAustmusia,Buyina,Calacadia,Cunnawarra,Jalkaraburra,Keera,Magua,Metaltella,PenaoolaandQuemusia; Porteriinae (new rank), withBaiami,Cambridgea,CorasoidesandNanocambridgea(transferred from Stiphidiidae); and Desinae, withDesis, and provisionallyPoaka(transferred from Amaurobiidae) andBarahna(transferred from Stiphidiidae).Argyronetais transferred from Cybaeidae to Dictynidae.Cicurinais transferred from Dictynidae to Hahniidae. The generaNeoramia(from Agelenidae) andAorangia,MarplesiaandNeolana(from Amphinectidae) are transferred to Stiphidiidae. The family Toxopidae (restored status) includes two subfamilies: Myroinae, withGasparia,Gohia,Hulua,Neomyro,Myro,OmmatauxesisandOtagoa(transferred from Desidae); and Toxopinae, withMidgeeandJamara, formerly Midgeeinae,new syn.(transferred from Amaurobiidae) andHapona,Laestrygones,Lamina,ToxopsandToxopsoides(transferred from Desidae). We obtain a monophyletic Oval Calamistrum clade and Dionycha; Sparassidae, however, are not dionychans, but probably the sister group of those two clades. The composition of the Oval Calamistrum clade is confirmed (including Zoropsidae, Udubidae, Ctenidae, Oxyopidae, Senoculidae, Pisauridae, Trechaleidae, Lycosidae, Psechridae and Thomisidae), affirming previous findings on the uncertain relationships of the “ctenids”AncylometesandCupiennius, although a core group of Ctenidae are well supported. Our data were ambiguous as to the monophyly of Oxyopidae. In Dionycha, we found a first split of core Prodidomidae, excluding the Australian Molycriinae, which fall distantly from core prodidomids, among gnaphosoids. The rest of the dionychans form two main groups, Dionycha part A and part B. The former includes much of the Oblique Median Tapetum clade (Trochanteriidae, Gnaphosidae, Gallieniellidae, Phrurolithidae, Trachelidae, Gnaphosidae, Ammoxenidae, Lamponidae and the Molycriinae), and also Anyphaenidae and Clubionidae.Orthobulais transferred from Phrurolithidae to Trachelidae. Our data did not allow for complete resolution for the gnaphosoid families. Dionycha part B includes the families Salticidae, Eutichuridae, Miturgidae, Philodromidae, Viridasiidae, Selenopidae, Corinnidae and Xenoctenidae(new fam., includingXenoctenus,ParavulsorandOdo, transferred from Miturgidae, as well asIncasoctenusfrom Ctenidae). We confirm the inclusion ofZora(formerly Zoridae) within Miturgidae.

    more » « less
  5. Morphological characters and nuclear ribosomal DNA (rDNA) phylogenies have so far been the basis of the current classifications of arbuscular mycorrhizal (AM) fungi. Improved understanding of the evolutionary history of AM fungi requires extensive ortholog sampling and analyses of genome and transcriptome data from a wide range of taxa. To circumvent the need for axenic culturing of AM fungi we gathered and combined genomic data from single nuclei to generate de novo genome assemblies covering seven families of AM fungi. We successfully sequenced the genomes of 15 AM fungal species for which genome data was not previously available. Comparative analysis of the previously published Rhizophagus irregularis DAOM197198 assembly confirm that our novel workflow generates genome assemblies suitable for phylogenomic analysis. Predicted genes of our assemblies, together with published protein sequences of AM fungi and their sister clades, were used for phylogenomic analyses. We evaluated the phylogenetic placement of Glomeromycota in relation to its sister phyla (Mucoromycota and Mortierellomycota), and found no support to reject a polytomy. Finally, we explored the phylogenetic relationships within Glomeromycota. Our results support family level classification from previous phylogenetic studies, and the polyphyly of the order Glomerales with Claroideoglomeraceae as the sister group to Glomeraceae and Diversisporales. 
    more » « less