taxonID	type	description	language	source
03B787C4D36EFF81FCECD12C31EBFCCB.taxon	description	Taxonomists faced problems in species delimitation of the M. pulicaria species complex for almost 200 years. Using an in-depth integrative taxonomy approach, we propose the species status for two out of eight names that are currently in synonymy of M. pulicaria (WSC, 2019). We applied data from morphology, mitochondrial DNA and ecology (Table 1), and species were accepted only if they differed in all three disciplines. This is based on rationales provided by Schlick-Steiner et al. (2010), who demonstrated that three disciplines are required to lower the average error rate in species delimitation below 5 %. This may be considered a conservative approach. Nowadays, many species are described primarily based on molecular delineation (Atherton & Jondelius, 2018; Zhang et al., 2018), and Barcode Index Numbers (BINs) are frequently used as a species proxy (Hebert et al., 2016). In our study, reliance exclusively on molecular delineation methods would result in splitting M. pulicaria into seven species, of which only two were morphologically distinguishable. We do not consider morphological differentiation essential for species distinction, as morphological crypsis among species is not uncommon (Bickford et al., 2007). However, we assume that morphological variation reflects genome-wide divergence better than single gene trees. This effect is shown in the lower failure rate of morphology as compared to mitochondrial DNA and nuclear DNA in a literature survey on species delimitation (Schlick-Steiner et al., 2010). More importantly, molecular delimitation methods detect lineages, which must not necessarily correspond to species. It is well known that popular delineation methods that were designed for single-locus molecular data, such as GMYC, PTP and BIN, tend to overestimate species diversity (Carstens, Pelletier, Reid, & Satler, 2013; Hawlitschek, Scherz, Ruthensteiner, Crottini, & Glaw, 2018; Luo, Ling, Ho, & Zhu, 2018; Miralles & Vences, 2013). In a recent simulation study, Sukumaran and Knowles (2017) have convincingly shown that even the multispecies coalescent model, which is increasingly used with genomic data, consistently overestimated the number of true species due to misidentification of population structure for species entities. Since overinflation of species numbers may have serious consequences, for example in global biodiversity estimates or for conservation strategies (Larsen, Miller, Rhodes, & Wiens, 2017; Robuchon et al., 2019) the integration of genetic and nongenetic sources of data (morphological, ecological and ethological information) is generally recommended. In our Micaria example, OTU- 2 populates vast areas of the Holarctic region with its complex Pleistocene climatic history. Therefore, lineage sorting is not expected to be complete and we predict a profound genetic structure that should not be mistaken for putative species unless supported by other lines of evidence. While we are confident that the relatively deep divergence within Palearctic M. pulicaria (OTU- 2) is attributable to phylogeographic structure instead of speciation, the situation is more challenging with respect to species status of OTU- 3. This clade is exclusively Nearctic and overlaps with OTU- 2 only in a small area near the Pacific coast. The oldest available name for North-American specimens is Micaria montana Emerton, 1890 with the type locality Mt. Washington situated in New Hampshire. Since only OTU- 3 occurs in this region, this would be the valid name for the widespread North-American clade. The morphometric analysis (Figure 5 a, b) confirms that the holotype of M. montana as well as type material of M. gentilis Banks, 1896 and M. perfecta Banks, 1896 correspond to OTU- 3. The crucial question is whether OTU- 3 should be considered conspecific with OTU- 2 or not. Our data suggest diagnostic substitutions for each clade in the COI gene. However, we do not know whether these characters would remain specific if the sampling was more comprehensive than in our study (Bergsten et al., 2012). On the other hand, we did not detect significant differences in morphological characters nor in ecology between OTU- 2 and OTU- 3. For the sake of taxonomic stability, we therefore advocate to keep M. montana (and also M. gentilis and M. perfecta) in the synonymy of M. pulicaria, as proposed by Hackman (1954) and Platnick and Shadab (1988) until contradicting evidence is provided. Phylogenomic data may once decide upon this matter.	en	Muster, Christoph, Michalik, Peter (2020): Cryptic diversity in ant-mimic Micaria spiders (Araneae, Gnaphosidae) and a tribute to early naturalists. Zoologica Scripta 49 (2): 197-209, DOI: 10.1111/zsc.12404, URL: https://doi.org/10.1111/zsc.12404
03B787C4D361FF82FCF7D34C3510FE71.taxon	description	The spider fauna of central Europe is well known. In such faunas, the detection of hidden diversity is a rare phenomenon. Moreover, M. pulicaria is a common species. According to the Atlas of the European Arachnids (https: // atlas. arages. de /), the species is placed 59 out of 1,050 in descending order of grid frequencies of spider species in Germany. Thus, it is rather surprising that two widespread species have been mistaken for such a long time. If one accepts the definition of cryptic species as two or more distinct species that were earlier classified as one (Bickford et al., 2007), then M. micans and pulicaria are cryptic species. Processes underlying the evolution of morphological crypsis have gained vast attention in recent years (Struck et al., 2018; Wagner et al., 2018). Which factors could have driven crypsis in Micaria spiders? The long-lasting taxonomic confusion of the two Micaria species certainly relates to the high levels of intraspecific variation as compared to low interspecific dissimilarity. On the one hand, the organization of both, the male palp and the female epigyne features, is simple as compared to other spiders, and few diagnostically useful characters exist. On the other hand, we found exaggerated variation within species — particularly in vulva structures — that is almost unrivalled in spiders (but see Crews, 2009). Spiders generally show no to very little intraspecific variation in genitalic characters (Kraus, 2002). However, spider genitalia are usually distinct even among closely related species and thus reliable indicators of species limits (Huber, Rheims, & Brescovit, 2005). The reasons for higher intraspecific variation in spider genitalia in some taxonomic groups than in others are still not clear (Eberhard & Huber, 2010). We hypothesize that the high levels of standing variation within species as well as overall morphological stasis among the two Micaria species could be triggered by their myrmecomorphy. As frequency and distribution of model species changes, the mimics have to adapt, thus intraspecific polymorphism is an important characteristic of Batesian mimicry (Joron & Mallet, 1998). On the other hand, morphological conversion in the speciation process is constrained by selection towards maintenance of mimetic similarity with the model species. Hence, myrmecophily is listed as one source for the evolution of cryptic species in Bickford et al. (2007). Presumably, the exceptional high levels of variation within the two Micaria species also promoted character displacement in male genitalic traits. Reproductive character displacement is the selective process by which reproductive traits diverge in order to minimize the risks of hybridization; it results in a geographic pattern in which species are more dissimilar where they occur together than in allopatry (Pfennig & Pfennig, 2009). Exactly such a pattern has been observed in M. micans / pulicaria (Figure 5 a): Palearctic M. pulicaria (OTU- 2) and M. micans (OTU- 1), which occur sympatrically in vast areas of Eurasia, are separated in morphospace, while the Nearctic OTU- 3 takes an intermediate position. Although our morphometric analysis includes nongenitalic traits, the characters of the male palp contribute by far the highest loadings to shape PC 1. Moreover, species may also diverge in traits that are not directly involved in reproduction owing to correlated evolution with those traits actually targeted by character displacement (Pfennig & Pfennig, 2005). At the moment, we can only speculate whether character displacement in M. micans / pulicaria results from postspeciation divergence, for example reinforcement of specific differences that evolved in allopatry, for example through range contraction during Pleistocene glaciations, or if character displacement itself initiated speciation. During reproductive character displacement, female preferences on male traits may become so divergent that females in sympatry fail to recognize allopatric males as acceptable mates (or vice versa), ultimately resulting in reproductive isolation (Hoskin, Higgie, McDonald, & Moritz, 2005). Effective character displacement would also explain the absence of signals for introgression between M. pulicaria and micans. Introgression through occasional hybridization needs certainly to be considered in morphologically and ecologically similar congeners that occur in sympatry. Recent genomic studies have shown that it may be more prevalent in spiders than previously assumed (Ivanov, Lee, & Mutanen, 2018; Leduc-Robert & Maddison, 2018). However, we observed no single case of disagreement between morphology and mtDNA (i. e. no signs of mitonuclear discordance) in the studied Micaria species.	en	Muster, Christoph, Michalik, Peter (2020): Cryptic diversity in ant-mimic Micaria spiders (Araneae, Gnaphosidae) and a tribute to early naturalists. Zoologica Scripta 49 (2): 197-209, DOI: 10.1111/zsc.12404, URL: https://doi.org/10.1111/zsc.12404
