Review of Erigonine spider genera in the Neotropics (Araneae: Linyphiidae,Erigoninae)

The Neotropical genera of the linyphiid spider subfamily Erigoninae are revised at the genus level. Emphasis was placed on genera endemic to the Neotropics and species with dubious relationships to their nominal genera, especially species from the older literature. This work recognizes 50 genera in the Neotropics, of which 39 genera are strictly endemic to the Neotropics, three are represented outside the Neotropics by one species, and eight genera have significant representation both in and beyond the Neotropics. Three additional genera, Ceraticelus Simon, 1884, Idionella Banks, 1893, and Eulaira Chamberlin & Ivie, 1933, are represented in northern Mexico and/or the West Indies, but are best classified as having a Nearctic or Holarctic distribution. Species previously placed in the typically northern hemisphere genera Gongylidiellum Simon, 1884, Leptorhoptrum Kulczynski, 1894, Macrargus Dahl, 1886, Minyriolus Simon, 1884, Oedothorax Bertkau, 1883, Phanetta Keyserling, 1886, and Tmeticus Menge, 1868 are found to be misplaced or nomina dubia; two genera endemic to the Neotropics, Clitistes Simon, 1902 and Zilephus Simon, 1902 are nomina dubia. The genus Beauchenia Usher, 1983 is an erigonine, not a mynoglenine; there are no known representatives of the Mynogleninae in the Neotropics. One hundred and forty new combinations are established; 19 genera are synonymized including Micromaso Tambs‐Lyche, 1954, revalidation rejected; 34 species are synonymized. The following new genera are established: Gigapassus gen. nov. , Intecymbium gen. nov. , Moyosi gen. nov. , Orfeo gen. nov. and Toltecaria gen. nov. Malkinella Millidge, 1991 and Valdiviella Millidge, 1985 are preoccupied; Malkinola nom. nov. and Valdiviola nom. nov. are established as replacement names. The following new species are described: Asemostera daedalus sp. nov. , Asemostera enkidu sp. nov. , Asemostera janetae sp. nov. , Fissiscapus attercop sp. nov. , Gonatoraphis lysistrata sp. nov. , Gravipalpus standifer sp. nov. , Microplanus odin sp. nov. , Moyosi chumota sp. nov. , Myrmecomelix leucippus sp. nov. , Neomaso damocles sp. nov. , Notiomaso exonychus sp. nov. , Paraletes pogo sp. nov. , Psilocymbium acanthodes sp. nov. , Smermisia holdridgi sp. nov. and Smermisia parvoris sp. nov. The following species remain misplaced in inappropriate genera: Erigone fellita Keyserling, 1886, Erigone zabluta Keyserling, 1886, and Oedothorax fuegianus (Simon, 1902). For 23 species, type specimens could not be located and the species could not be unambiguously identified; the type of Macrargus pacificus Berland, 1924 could not be located, but it is transferred to Laminacauda Millidge, 1985. The female of Onychembolus subalpinus Millidge, 1985 described by Millidge in 1991 is mismatched; this female is Notiomaso exonychus sp. nov. ; the true female of Onychembolus subalpinus was described as both Neomaso bidentatus Millidge, 1991 syn. nov. and Neomaso tridentatus Millidge, 1991 syn. nov. The male and female of Asemonetes[now Asemostera]arcana (Millidge, 1991) are not conspecific; a male thought to be conspecific with the female of A. arcana is newly described; the true female of A. arcana is unknown. The transfer of Emenista dentichelis Berland, 1913 to Laminacauda comb. nov. renders Laminacauda dentichelis Millidge, 1991 a junior homonym; the replacement name Laminacauda baerti nom. nov. is provided for Laminacauda dentichelis Millidge. The following species were erroneously placed in erigonine genera: Oedothorax bisignatus Mello‐Leitão, 1945 is synonymized with Theridion calcynatum Holmberg, 1876 syn. nov. (Theridiidae); Liger incomta O. Pickard‐Cambridge, 1896 is transferred to Theridion Walckenaer, 1805 (Theridiidae) [Theridion incomtum comb. nov. ]; Erigone ectrapela Keyserling, 1886 is transferred to Dictyna Sundevall, 1833 (Dictynidae) [Dictyna ectrapela comb. nov. ]; Erigone peruana Keyserling, 1886 is transferred to Thymoites Keyserling, 1884 (Theridiidae) [Thymoites peruanus comb. nov. ]; Adelonetria dubiosa Millidge, 1991 is not a linyphiid and will be dealt with elsewhere. Lomaita darlingtoni Bryant, 1948 is confirmed as a linyphiid, not a mysmenid. © 2007 The Linnean Society of London, Zoological Journal of the Linnean Society, 2007, 149 (Suppl. 1), 1–263.     

Cladistic analysis of molecular and morphological data

Considerable progress has been made recently in phylogenetic reconstruction in a number of groups of organisms. This progress coincides with two major advances in systematics: new sources have been found for potentially informative characters (i. e., molecular data) and (more importantly) new approaches have been developed for extracting historical information from old or new characters (i. e., Hennigian phylogenetic systematics or cladistics). The basic assumptions of cladistics (the existence and splitting of lineages marked by discrete, heritable, and independent characters, transformation of which occurs at a rate slower than divergence of lineages) are discussed and defended. Molecular characters are potentially greater in quantity than (and usually independent of) more traditional morphological characters, yet their great simplicity (i. e., fewer potential character states; problems with determining homology), and difficulty of sufficient sampling (particularly from fossils) can lead to special difficulties. Expectations of the phylogenetic behavior of different types of data are investigated from a theoretical standpoint, based primarily on variation in the central parameter λ (branch length in terms of expected number of character changes per segment of a tree), which also leads to possibilities for character and character state weighting. Also considered are prospects for representing diverse yet clearly monophyletic clades in larger-scale cladistic analyses, e. g., the exemplar method vs. “compartmentalization” (a new approach involving substituting an inferred “archetype” for a large clade accepted as monophyletic based on previous analyses). It is concluded that parsimony is to be preferred for synthetic, “total evidence” analyses because it appears to be a robust method, is applicable to all types of data, and has an explicit and interpretable evolutionary basis. © 1994 Wiley-Liss, Inc.     

The Gegenbaur Transformation: a paradigm change in comparative biology

The leading experts in the development of phylogenetic systematics, Walter Zimmermann and Willi Hennig, formulated their research program in opposition to (neo-) idealistic morphology as expounded by authors such as Wilhelm Troll and Adolf Naef. Idealistic morphology was synonymous with systematic morphology for Naef, who wanted it to be strictly kept separate and independent of phylogenetics. Naef conceded, however, that the natural system researched by systematic morphology is to be causally explained by the theory of descent with modification. Naef went on to compile a dictionary that would regulate the translation of the language of systematic morphology into the language of phylogenetics. The switch from idealistic morphology to phylogenetic morphology is paradigmatically exemplified in the two editions (1859, 1870) of Carl Gegenbaur's Grundzüge der vergleichenden Anatomie. This paper traces the development of phylogenetic systematics from Gegenbaur through the work of Adolf Naef to Walter Zimmermann and Willi Hennig. Hennig added to Naef's systematic morphology the dimension of time, which required an ontological replacement: Naef's natural system, a nested hierarchy of intensionally defined sets subject to the membership relation, was replaced by Hennig's phylogenetic system, an enkaptic hierarchy subject to the part-to-whole relation.     

Trees before and after Darwin

Phylogenetic trees published before Darwin’s On the Origin of Species are scarce. Lamarck (1809) and Barbançois (1816; J Phys Chim Hist Nat Arts 82, 444) are the first and only trees devoted to illustrating the genealogical connections between organisms of different species and different higher taxa. In the late 18th and early 19th centuries, most of the trees depicted in papers dealing with natural history were classifications; classifications in the shape of trees, but classifications nonetheless. Those published by Bronn (1858) are a good example. After Darwin, phylogenetic trees incorporating the time dimension flourished. In the first half of the 20th century, the Modern Synthesis failed to renew and rejuvenate the intuitive construction of trees. It wasn’t until the appearance of Hennig’s phylogenetic systematics that the real nature of the connection between phylogeny and the pre‐Darwinian concept of homology was made clear.     

Adolf Naef (1883–1949), systematic morphology and phylogenetics

Several authors have highlighted methodological similarities between Naef’s systematic morphology and Hennig’s phylogenetic systematics. Whereas this may indicate an influence of Naef on Hennig, the relevant issues – such as the principle of generality in character analysis and the threefold parallelism of classification, ontogeny and the Fossil Record – reach back beyond Naef and Hennig and were widely discussed in the German systematics literature of the late 19th and early 20th Century. The same is true of conceptual issues, such as the discussion of the principle of monophyly, which was first introduced by Haeckel in 1866 ( Rieppel 2011b , J Zool Syst Evol Res 49 :1). In spite of methodological and conceptual agreements, Naef’s systematic morphology differed fundamentally from Hennig’s phylogenetic systematics. Naef emphasized the role of unbiased observation and the immediate acquaintance of the investigator with the phenomena given in nature as the basis of natural science in general, and of his hierarchy of types in particular. From the hierarchy of types, Naef derived through conceptual‐logical analysis the natural system, which above the species level forms a nested hierarchy of intensionally defined classes, denoted by general names. The historical‐causal interpretation of the hierarchy of types in turn offers insight into the hypothetical reality of phylogeny. Hennig in contrast denied the possibility of theory‐free observation, indeed of assumption‐free science in general, and on that basis put metaphysical issues above epistemology. Tying individuality to spatiotemporal location, historicity and causality, Hennig took not only species (as did Naef) but also supraspecific monophyletic taxa as individuals, denoted by proper names. From the species up, the phylogenetic system thus becomes a nested hierarchy of complex wholes of increasing degrees of complexity. Diagnostic characters of species or higher taxa can then no longer define classes (as in Naef’s natural system) but are thought to indirectly indicate the phylogenetic relations on which alone the phylogenetic system is to be based.     

On the difference between mono-, holo-, and paraphyletic groups: a consistent distinction of process and pattern

About 50 years ago, the German entomologist Willi Hennig presented a new approach in biological systematics that he called a phylogenetic systematics. The main difference between his approach and traditional Linnean systematics was that he distinguished two new kinds of groups that he called mono- and paraphyletic groups, and whereof he considered only monophyletic groups to be natural groups. However, almost immediately after publication of his approach in English, some biological systematists commented that his monophyletic groups rather ought to be called holophyletic groups. The comment sparked a heated debate about the definition of the concept 'monophyletic groups', but the debate never reached consensus. In this paper, I claim that the controversy does not concern the definition of the concept monophyletic groups per se , but instead conceptualization of phylogenies (i.e. dichotomously branching processes) in a general sense. I discuss the relation between mono-, holo- and paraphyletic groups, and conclude that Hennig's conceptualization of phylogenies is both inconsistent and empirically wrong, whereas Linné's instead is consistent and correct.  © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 94 , 217–220.     

A cladistic analysis of Hydrophis subgenus Chitulia (McDowell, 1972) (Serpentes, Hydrophiidae)

The Hydrophis subgenus Chitulia was analysed using the computer program Hennig86 (version 1.5). The character data set comprises 22 two-state characters, giving a minimum of 22 steps. Four trees with a length of 37 steps and a consistency index of 0.59 were found using the "ie*" option. The results indicate that the subgenus Chitulia is paraphyletic, and that the group has been based solely on plesiomorphic character states. The order of taxa input, the display of the root, and the effect of unknown character states using Hennig86 are commented on.