Anapidae Simon, 1895
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publication ID |
https://doi.org/ 10.3897/zookeys.11.160 |
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publication LSID |
lsid:zoobank.org:pub:C631A347-306E-4773-84A4-E4712329186B |
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DOI |
https://doi.org/10.5281/zenodo.3792240 |
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persistent identifier |
https://treatment.plazi.org/id/03ACB915-FFAF-7426-FF4E-40E0FBC8F93F |
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treatment provided by |
Plazi |
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scientific name |
Anapidae Simon, 1895 |
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Family Anapidae Simon, 1895 View in CoL View at ENA
The terminology used for the labrum is confused and confusing. In particular the terms “labral sclerite” and labral spur” have been used in synonymous and differing ways. An anteriorly projecting spur in the mouth region was recognized as early as Wunderlich (1976: figs 37, 38, “Sporn des Labium”), who erroneously referred to a spur on the labium (rather than the labrum). Platnick and Shadab (1978a) suggested that an “anterior labral spur” was a synapomorphy for a redefined Anapidae , illustrated in their figure 1 of Anapis keyserlingi Gertsch, 1941 . This labral spur was also depicted for Anapisona hamigera (Simon, 1897) by Platnick and Shadab (1979: fig. 10).
Subsequently arguments about the monophyly of, and placement in, Anapidae have hinged on the labral spur. We contend that this has never been precisely defined, and that this lack of a precise definition has fueled confusion. We suggest that there are at least three separate structures of the labrum that have been referred to as a spur. One of these is clearly the spur of Platnick and Shadab, but this is restricted to a mere handful of genera and does not characterize the majority of species currently placed in the Anapidae .
Snodgrass (1952: figs 31A, B) depicts in detail the pharynx, epistome, and labrum of a theraphosid spider. In these illustrations one can see structures that are widespread in Araneae , including the symphytognathoids. The labrum is a region of sclerotized cuticle just anterior to the epistome, the latter being the point of attachment for a pair of median dilator muscles of the pharynx. The morphology of the labrum was clearly described in detail by Kropf (1990). The labrum connects the palpal coxae in front of the mouth opening and bears a sclerite on its anterior wall, which Kropf (1990) calls the “labral sclerite” ( Kropf 1990: figs 1, 6). There is a flattened, anteriad pointing labral tongue (“labral flap” of Lopardo and Hormiga 2008) that arises from the anterior face of the labrum with the apex projecting obliquely downward and towards the chelicerae. The apex is free and may be truncate, rounded, or deeply cleft. Beneath and beyond the apex there are short, smooth setae, which contrast to the plumose setae elsewhere on the labrum. Kropf (1990) refers to these as “minute, cuticular, bristle-like pins” arising from a cavity covered by the sclerite. These features occur widely in Araneomorphae ( Fig. 93 View Figure 93 A-F). Posteriad of the base of the labral tongue the cuticle may be smooth and convex, or weakly to profoundly divided by a transverse groove. We think that these features are homologous across Araneomorphae (at least), and that they provide landmarks that enable precise definition of labral homologies.
Both Anapis Simon, 1895 ( Fig. 58C, D View Figure 58 ) and Anapisona Gertsch, 1941 ( Fig. 58A, B View Figure 58 ) have a large, anterodorsad pointing swelling at the base of the tongue. This is clearly the “spur” of Platnick and Shadab (1978a: fig. 1, 1979: fig. 10). But this feature is peculiar to only a few spiders, particularly Anapis and Anapisona . Most taxa assigned to Anapidae have no such structure, though the region at the base of the tongue may be more or less swollen ( Figs 58E, F View Figure 58 , 62C, D View Figure 62 ). Some Anapis species have an additional swelling, arising far posteriad of the base of the labral tongue. This was illustrated in Griswold et al. 1998 (fig. 20A, C) and mistakenly taken to typify the character labral spur.
To our knowledge all taxa currently assigned to Anapidae (and to other symphytognathoid families as well) have the labral tongue (Figs 41E, F, 62C, D, 70E, F), whereas the majority of taxa assigned to Anapidae lack the true labral spur sensu Platnick and Shadab. Confusion of the labral tongue with the labral spur has led to pointless arguments about the scope and monophyly of Anapidae . For example, Schütt (2000) discusses the mouthpart of anapids and micropholcommatids, illustrates the labra of the members of the former ( Schütt, 2000: fig. 5A–C) and the latter families ( Schütt, 2000: fig. 5E, F), notes close resemblance, and concludes that all have a labral spur. Whereas all have a labral tongue, none have the projecting spur from the base of the tongue that typifies the labral spur sensu Platnick and Shadab. Likewise, Lopardo and Hormiga (2008), in their discussion of the placement of Acrobleps , note that this is unusual among the Anapidae in the absence of a labral spur. In fact, most anapids lack the spur. Most anapids, including the new genus Gaiziapis ( Fig. 62 C, D View Figure 62 ) and Gertschanapis Platnick & Forster, 1990 ( Fig. 58 View Figure 58 E-F, coded as present for the labral spur in Griswold et al. 1998), micropholcommatids, and Acrobleps ( Lopardo and Hormiga 2008: fig. 12C-F), have the base of the tongue slightly swollen and raised higher than the level of the tongue apex. This subtle morphology may represent a synapomorphy at some level in the symphytognathoids, but deserves further survey.
Labral morphology may provide some corroboration for the monophyly of Symphytognathidae . The labra of the symphytognathid genera Patu Marples 1951 ( Fig. 70E, F View Figure 70 ) and Crassignatha ( Fig. 78B, C View Figure 78 ; see also Griswold et al. 1998: fig. 21A, B) have a spade shaped tongue typically bare dorsally except for a single, large plumose seta. This morphology differs from other araneoids and may prove to be a further synapomorphy for the Symphytognathidae .
There may be other post cheliceral characters that could be useful for future phylogenetic investigations, including the form of the labral tongue (entire, Figs 41E, 56E, 58E, 62C, 78B, Schütt 2000: fig. 5; or forked distally, Figs 58A, C View Figure 58 , 93D View Figure 93 , Miller et al. in review: fig. 2B), the margin between the endites and the labrum (rebordered, Fig. 58A, C View Figure 58 ; or simple, Figs 58E View Figure 58 , 62C View Figure 62 ), separation (Figs 41E, 56E) or fusion ( Figs 58A, C, E View Figure 58 , 62C View Figure 62 ) of the endites behind the labrum, the distribution of tubercles on the endites, and the presence of lateral protuberances in archaeids and their relatives ( Fig. 93B View Figure 93 ; Forster and Platnick 1984: fig. 90).
Ambiguities about the morphological characters that define the limits of Anapidae may help to explain the failure of structurally aligned ribosomal sequence data to recover either Anapidae or Anapidae plus Micropholcommatidae (cf. Schütt 2003) as monophyletic across several analytical permutations ( Rix et al. 2008). Rix et al. (2008) included a substantial sample of anapid taxa. Two genera, Risdonius Hickman, 1939 and Zealanapis Platnick & Forster, 1989 , are similar to the new genus Gaiziapis and consistently formed a well supported clade.
Diagnosis. Anapidae distinguished from other spider families in the Gaoligongshan except Symphytognathidae by the following combination of characters: the lack of a female pedipalp ( Fig. 59C View Figure 59 ) and male epiandrous gland spigots ( Fig. 62F View Figure 62 ), and by the insertion of the pedicel through an opening in the posterior declavity of the carapace ( Figs 59C View Figure 59 , 63E, F View Figure 63 ); distinguished from Symphytognathidae by having the chelicerae free to the base. Further distinguished from most other spiders in the Gaoligongshan by having the all tarsi more than 1.5 times the length of the metatarsi ( Fig. 59A, C View Figure 59 ). The base of the labrium in Anapidae from the Gaoligongshan is slightly swollen, as high as or higher than the apex of the labral tongue ( Fig. 62D View Figure 62 ) but the labral spur is absent (see above). Gaiziapis zhizhuba sp. n. is the only anapid known fromthe Gaoligongshan.
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