Batillipes phreaticus Renaud-Debyser, 1959

Santos, Erika, Rubal, Marcos, Veiga, Puri, da Rocha, Clélia M. C. & Fontoura, Paulo, 2018, Batillipes (Tardigrada, Arthrotardigrada) from the Portuguese coast with the description of two new species and a new dichotomous key for all species, European Journal of Taxonomy 425, pp. 1-32 : 17-19

Batillipes phreaticus Renaud-Debyser, 1959

Fig. 8

Material examined

PORTUGAL: 1 ♂, collected at Ilha de Tavira Beach, mounted in glycerol (slide C.10-79); 1 juvenil collected at Baleal Sul Beach, mounted in PVA (slide C.10-13); 34 specimens (22 ♀♀, 8 ♂♂, 3 juveniles and 1 four-toed larva), collected at Meia-Praia Beach, mounted in glycerol (slides C.VII.89, C.IX.1, C.IX-2; C.IX-37–C.IX-39, C.IX-41–C.IX-43, C.IX-47, C.IX-50–C.IX-52, C.IX-55–C.IX-58, C.IX- 60–C.IX-64, C.IX-66, C.IX-67); 116 specimens (42 ♀♀, 37 ♂♂, 33 juveniles and 4 four-toed larvae), collected at Vasco da Gama Beach, mounted in glycerol (slides C.IX-75–C.IX-86, C.IX-88–C.IX-98).

Short description

Distinct head separated from the body by a neck constriction followed by well-developed lateral processes ( Fig. 8A ). Eyes not observed in mounted specimens. Caudal apparatus constituted by one major pointed spine surrounded, at its base, by a crown of small accessory spines (2 to 6) ( Fig. 8B ). Paired internal and external cephalic cirri and median cirrus all with lance-like tips. Surface of primary clavae with black punctations, sharing the same pedestal with the lateral cirri A, that also have a lancelike tip. Papillar secondary clavae present. Dorsal cuticle shows fine punctuation, with pillars uniformly distributed. Single sharp conical body projections between legs III and IV ( Fig. 8B ). Lateral body projections between the first three pairs of legs often indistinct. When present, they are blunt between legs I–II and triangular between legs II–III. Dorsal cirri E present. Sensory spines on all legs, longer on legs IV ( Fig. 8B ). Middle toes (3 and 4) on feet of legs IV ( Fig. 8C ) equal in length.

Distribution

Interstitial species recorded in the Eastern Atlantic region (Atlantic Ocean, North Sea, Irish Sea and Celtic Sea) and in the Mediterranean Basin (Balearic and Ionian Seas) where it has been recorded,

mostly intertidally, but also subtidally ( Kaczmarek et al. 2015). Batillipes phreaticus was recorded from the Galician coast, NW Spain ( Veiga et al. 2009), but this is the first record from Portugal.

Associated species

Batillipes adriaticus , B. algharbensis sp. nov., B. lusitanus sp. nov., B. pennaki and H. greveni .

Remarks

In the original description of B. phreaticus from Arcachon Bay, France (Celtic Sea), the presence of lateral body projections between the first three pair of legs is not referred ( Renaud-Debyser 1959).

Concerning toes, Renaud-Debyser (1959) states that they are similar to those of B. littoralis (also from Arcachon Bay), which are described in the same publication as having stalks of different lengths. However, the relative size of toes and details of the arrangement among feet were not referred by Renaud-Debyser (1959).

Specimens from England, Filey Beach and Stoup Beck Beach, Yorkshire, collected by Pollock (1971) and from Germany, Elbe Estuary ( Riemann 1966) attributed to B. phreaticus , differed from the original description in some morphometric aspects and in having lateral body projections often present ( Pollock 1971). Moreover, Pollock (1971) noticed that in English specimens, the middle toes (toes 3 and 4) on feet of legs IV were equal in length. Later, Villora-Moreno & de Zio Grimaldi (1993), based on specimens collected on sandy beaches from the Mediterranean Sea (Balearic Sea), provided a redescription of the species, confirming the differences mentioned by Pollock (1971), regarding the original description: presence in adult specimens of a ventro-lateral body projection between legs II and III, and middle toes on feet of legs IV equal in length (toe pattern group A, Pollock 1970a). Despite his own observations, Pollock (1971) did not correct his proposal from 1970 of three different patterns of toe arrangement within Batillipes species, having included B. phreaticus in group B, which considers middle toes on feet of legs IV of different length and toe 1 equal to 3, while B. littoralis have been included in group C (middle toes on feet of legs IV of different length and toe 2 equal to 4).

The system of toe arrangement patterns on the fourth feet of species of Batillipes species was modified by Kristensen & Mackness (2000), who proposed a fourth group (group D, constituted by species with middle toes of different length and also different from all the other toes). As previously proposed by Pollock (1970a), B. phreaticus and B. littoralis were kept in groups B and C, respectively, by Kristensen & Mackness (2000).

Taking into account the taxonomic importance of those characters ( Gallo D’Addabbo et al. 2000), the examination of type material of those two species deposited in the collection of the MNHN was of primordial importance. This examination showed that the toe pattern of the fourth feet of B. littoralis perfectly matches the group D proposed by Kristensen & Mackness (2000). Concerning B. phreaticus , despite the poor condition of the specimen, the middle toes of the fourth feet seem to be equal in length and shorter than all the other, from which, toes 2 and 5 are the longest and about the same length, and toes 1 and 6, also similar in size and of intermediate length (toe pattern of group A). One of the examined specimens from Scotland collected by Pollock in 1981 also exhibits the middle toes of the fourth feet equal in length ( Fig. 8D ). Unfortunately, this character was not visible in the other Scottish specimen deposited in the MNHN (slide AR607).

Therefore, specimens from the Portuguese coast match with observations of Pollock (1971) and Villora- Moreno & de Zio Grimaldi (1993). Ventro-lateral body projections between legs I–III were not observed in the type specimen, neither in the Scottish specimens. However, according to Pollock (1971) and as observed in Portuguese specimens, these lateral projections can be absent in some specimens or, as stated by Villora-Moreno & de Zio Grimaldi (1993), are indistinct as a result of slide preparation. It is important to remark that in a few adult specimens from Portugal (three specimens from Vasco da Gama Beach and six from Portinho da Arrábida Beach) the main caudal spine was inserted on a wide conical base, lacking the basal crown of small accessory spines as it occurs in juveniles. This ontogenetic variability of the morphology of the caudal appendage was also referred by Villora-Moreno & de Zio Grimaldi (1993).

Figures

Fig. 8. Batillipes phreaticus Renaud-Debyser, 1959. A–C. Portuguese specimens. A. Anterior region of the body. B. Posterior region of the body, black arrow indicates fourth leg sensory organ. C. Detail of the fourth feet. D. Detail of the fourth feet showing the toe arrangement pattern of a specimen from Scotland in Pollock’s collection. Scale bars = 10 µm.