Pycnogonida (Arthropoda) from Museu de Ciencias Naturais, Rio Grande do Sul, Brazil Author Lucena, Ruda Amorim https://orcid.org/0000-0002-4206-0357 Graduate Program in Biological Sciences- Zoology, Federal University of Paraiba, University Campus, Joao Pessoa, Paraiba, CEP: 58051 - 900, Brazil rudalucena15@gmail.com Author Lindsey Christoffersen, Martin https://orcid.org/0000-0001-8108-1938 Graduate Program in Biological Sciences- Zoology, Federal University of Paraiba, University Campus, Joao Pessoa, Paraiba, CEP: 58051 - 900, Brazil text Zoosystematics and Evolution 2022 2022-07-20 98 2 305 312 http://dx.doi.org/10.3897/zse.98.83671 journal article http://dx.doi.org/10.3897/zse.98.83671 1860-0743-2-305 10FA5741370A4ABFA43298A2DE65BCE3 9BD32E16AD7354B598BD1D030B9F3881 Colossendeis megalonyx Hoek, 1881 Fig. 3 Colossendeis frigida Hodgson, 1902: 63. Colossendeis rugosa Hodgson, 1907: 64, pl. IX, fig. 3, pl. X, figs 5, 6. Colossendeis orcadense - Hodgson 1908 : 184. Colossendeis scoresbii Gordon, 1932: 18-21, figs 5c, 6b, c, 7a, b. Material examined. (FZB.Pyc-002) 1 female , South Atlantic , July 8, 1964 ; (FZB.Pyc-004) 5 females , off Mar del Plata , Argentina ( 38°22'S , 55°37'W ), May 1961 , col. L.R. Pontes ; (FZB.Pyc-005) 1 female , Uruguay , Mar1961 . Figure 3. Colossendeis megalonyx (FZB.Pyc-002), female. A. Dorsal view; B. Distal articles of palp; C. Distal articles of oviger; D. Tarsus and propodus. Distribution. Circumpolar. Antarctic, Western South America and up to Buenos Aires (Argentina), South Africa, Madagascar, New Zealand, Eastern South America ( Child 1995a ; Munilla and Soler-Membrives 2009 ; Scarabino et al. 2019 ). This is the first record for Uruguayan waters. Depth. 7 to 4900 m in depth. Remarks. Colossendeis megalonyx is a very variable species ( Fry and Hedgpeth 1969 ; Child 1998b ) and may represent a group of cryptic species. Only the long proboscis, palp article 8 shorter than articles 9 and 10 and a tarsus longer than the propodus remain stable amongst all examined specimens ( Child 1995a ). Variable characters are the shape and size of the ocular tubercle (elevated or short, conical or rounded), the occurrence of eyes (similar in size or larger anteriorly, well pigmented, white or even absent), the size of the proboscis (equal to, or longer than the trunk) and the size of the legs (either the femur or the tibia represent the longest article) ( Child 1995a , 1998b ; Cano-Sanchez and Lopez-Gonzalez 2007 ). Molecular studies confirm that a complex of species exists under the name C. megalonyx . Five species and another seven cryptic species were indicated ( Krabbe et al. 2010 ; Dietz et al. 2015 ; Doemel et al. 2020 ). These papers suggest the use of the name C. megalonyx for specimens from South America and the Subantarctic Region, the type locality ( Krabbe et al. 2010 ; Dietz et al. 2015 , 2019 ). Although morphology was not used for the delimitation of these species, subspecies were previously proposed by Fry and Hedgpeth (1969) . This indicates that morphology can be used successfully for the delimitation of species ( Cano-Sanchez and Lopez-Gonzalez 2007 ). Specimens analysed thus should belong to C. megalonyx , as they were collected in Uruguay (the northernmost record for the species, a full two degrees of latitude north of the record provided by Child (1995a) ). Further, they conform to the description of Hoek (1881) . Yet, variations in the shape of the ocular tubercle were observed, in some specimens this structure being conical and in others, rounded. All specimens had a proboscis 1.5 times as long as the trunk, on average, the same proportion observed by Stock (1963) for individuals identified as C. orcadensis . Although molecular analyses are an important new source of evidence, their results need to be correlated with detailed morphological analyses, in order to corroborate or refute the recent results with the older morphological work available in literature. Pallenopsidae Fry, 1978 Pallenopsis Wilson, 1881