Eskov K.Yu.1, Marusik Yu.M.2 2023. “Morphological” and “molecular” systems of araneoids: an attempt at harmonization with a subsequent testing of the obtained cladogram using web-building characters (Aranei: Araneoidea) // Arthropoda Selecta. Vol.32. No.3: 337–356 [in English].
1 Borissiak Paleontological Institute, Russian Academy of Sciences, Profsoyuznaya Str., 123, Moscow 117647, Russia. E-mail: afranius999@gmail.com
2 Institute of Biological Problems of the North, Far Eastern Branch, Russian Academy of Sciences, Portovaya Str., 18, Magadan 685000, Russia. E-mail: yurmar@mail.ru
doi: 10.15298/arthsel.32.3.10
ABSTRACT: The ‘three step protocol’ is proposed here for the purposes of practical taxonomy: (1) choosing the initial cladogram of a taxon, based on morphological characters; (2) correcting it using molecular characters (however, only that new ‘molecular clades’, which can be confirmed by independent — i.e., non-molecular — methods, should be accepted); (3) testing the obtained ‘harmonized morpho-molecular cladogram’, using independent behavioral (e.g., web-building) characters (and if they are harmonized too, such a cladogram may be adopted as a ‘natural system of the taxon’). For applying this protocol to the superfamily Araneoidea (22 families), the morphological cladogram by Griswold et al. [1998] was chosen as the basis; it was subsequently corrected using the well-supported molecular clade ‘enlarged Tetragnathoidea’ established by Dimitrov et al. [2017]. The resulting ‘harmonized morpho-molecular cladogram’ implies a splitting of a basal araneoid stock into the two principal branches: the ‘tetragnathoid branch’ (the malkaroid and tetragnathoid lineages) and the ‘araneoid branch’ (the araneoid, symphytognathoid, linyphioid, cyatholipoid, and theridioid lineages). Web-building characters strongly support such a division, and it seems to be a ‘natural system’ of the Araneoidea. Two opposite principal trends are evident in the evolution of web-building in the two principal superfamily branches: the transformation of the primary orb-web in ‘araneoids’ and its complete abandonment in ‘tetragnathoids’. The main general evolutionary trend in the araneoid branch is the replacing of the primary orb-web by various versions of sheet-webs: from the basal araneoid lineage (orb-webs only) to the terminal ‘araneoid sheet web builders clade’ (sheet-webs only), via the intermediate symphytognathoid lineage (both orb- and sheet-webs). The primary sheet-web is probably but a horizontal orb-web reduced up to a central hub lacking the edging spiral, and with radii transformed into vertical support-lines. Such a simplification of the web architecture allows the spiders to simplify their spinning apparatus too, as well as to minimize the required silk volume; both seem critically important during miniaturization, the key evolutionary trend in the symphytognathoid lineage. In addition, Pararchaeidae Forster et Platnick, 1984, Micropholcommatidae Hickman, 1944 and Comaromidae Wunderlich, 2004 are restored as independent families; Sinopimoidae Li et Wunderlich, 2008 is revalidated in the rank of a subfamily of the family Linyphiidae; Oarcinae Simon, 1890 is returned to Mimetidae from Araneidae; Taphiassinae Rix et Harvey, 2010 and Gigiellinae Rix et Harvey, 2010 are relocated to Anapidae from Micropholcommatidae; the placement of Holarchaea Forster, 1955 in Anapidae and of Gaucelmus Keyserling, 1884, Hamus Ballarin et Li, 2015, and Nescina Ballarin et Li, 2015 in Synotaxidae are confirmed by new data.
KEY WORDS: Araneae, system of Araneoidea, morphological and molecular characters, ‘tetragnathoid’ and ‘araneoid’ branches, web-building evolution.