Batillipes lusitanus, Santos & Rubal & Veiga & da Rocha & Fontoura, 2018

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 : 10-17

Batillipes lusitanus sp. nov.

urn:lsid:zoobank.org:act:EA994F4C-C1D9-4B43-871C-327A3CB644C4

Figs 4–7 ; Table 2

Diagnosis

Batillipes with tubular undivided primary clavae with a wrinkled surface. Conspicuous papillar secondary clavae. Cephalic cirri with lance-like distal tips. Sensory spines on all legs. A small rigid process is present in the distal extreme of legs IV. Toes 3 and 4 on feet of legs IV equal in length. A distinct head separated from the body by a neck constriction followed by well-developed lateral processes. Ventro-lateral body projections between all leg pairs present: small, often indistinct, between legs I– III and well developed, semicircular or slightly pointed, between legs III–IV. The caudal apparatus consists of a semicircular cuticular expansion. Dorsal cuticle constituted by large pillars (ca 3.2 µm high), appearing as large tubercles (diameter about 2–3 µm). Ventral cuticle finely punctated. Rosettelike female gonopore separated from the trilobed anus by a groove.

Etymology

The specific name ‘ lusitanus ’ refers to the locus typicus, Portugal, primitively known as Lusitânia, lusitanus = inhabiting Lusitânia.

Material examined

Holotype

PORTUGAL: ♀ adult, collected at Meia-Praia Beach, Lagos, Algarve, 37°7′1″ N, 8°38′37″ W, mounted in glycerol (slide C.IX-1).

Allotype

PORTUGAL: ♂ adult, collected at Meia-Praia Beach, Lagos, Algarve, 37°7′1″ N, 8°38′37″ W, mounted in glycerol (slide C.IX-2).

Paratypes

PORTUGAL: 78 specimens (19 ♀♀, 21 ♂♂, 37 juveniles and 1 four-toed larva), collected at Meia-Praia Beach, 37°7′1″ N, 8°38′37″ W, mounted in glycerol (slides C.IX-35–C.IX-66); 89 specimens (35 ♀♀,

14 ♂♂, 39 juveniles and 1 four-toed larva), collected at Afife Beach, 41°35′28″ N, 8°48′18″ W, mounted in PVA (slides C.IX-3–C.IX-34).

Description

Holotype, female of robust body 236 µm long (248.4 µm including the caudal apparatus) and 100.9 µm wide between the third and fourth pair of legs ( Figs 4 A–B, Table 2 for morphometrics). Eyes not observed in mounted specimens. Trapezoid head ( Figs 5 A–B) separated from the body by a neck constriction followed by well-developed lateral processes (body projection 1). Head with eleven cephalic appendages: Internal cephalic cirri with cirrophores (ca 3.4 µm long), are inserted dorsally on the frontal edge of the head ( Fig. 5A ). External cephalic cirri, with indistinct cirrophores, inserted more ventrally, near the lateral cirri A and primary clavae ( Fig. 5B ). The median cirrus with cirrophore. The lateral cirrus A located dorsally in relation to the unconstricted tubular primary clava. These two appendages share a common pedestal. A van der Land’s organ present at the base of primary clavae, which have a wrinkled surface and exhibit a terminal hole ( Figs 5 A–B). An indentation present in the frontal edge of the head between the external cephalic cirrus and the pedestal with the primary clava and lateral cirrus. Papillar secondary clavae ( Fig. 5A ) well visible (major diameter ca 7.5 µm long). Cephalic cirri, including the external cirri and the lateral cirri with swollen tips. Ventral mouth opening in a protruded circular structure. Ovoid pharyngeal bulb, 28.1 µm long and 25.5 µm wide, with placoids (ca 17.2 µm long).

Well-developed blunt ventro-lateral processes between legs III and IV (body projection 4) ( Figs 5C , 6A ). The caudal apparatus consists of a prominent semicircular projection ( Figs 4 A–B, 6C, 7A–B).

Sensory spines present on all legs, increasing in length from leg I to IV. First and fourth leg sensory organs with swollen tips. The sensory organ on leg IV divided into a cirrophore (not measurable in the holotype but observed in paratypes) and a basal portion (7.1 µm long) separated from a distal portion (14.5 µm long) by a van der Land’s organ ( Fig. 5D ). Sharply pointed cirri E with small cirrophores present.

Telescopic legs with toes with the distal stalk enlarged distally (ca 3.5 µm wide), ovoid suction discs (5.2 × 5.1 µm) and conspicuous braces ( Fig. 6A ). On feet of the first three pairs of legs, toe 2 is the shortest, toes 3 and 5 are the longest and toes 1, 4 and 6 are medium sized. On feet of the fourth pair of legs, ( Fig. 6 A–B) the medial toes 3 and 4 are equal in length. Toes 1 and 6 are medium sized; toe 2 and especially toe 5 are the longest. A small rigid process (ca 3 µm long) is present in the distal extreme of legs IV ( Fig. 6B ).

The punctation of the dorsal cuticle is very peculiar. It is constituted by large pillars (about 5 pillars / 10 µm, each pillar with ca 3.6 µm high) that, when observed under PCM and DIC, appear as large tubercles, especially if observed laterally ( Fig. 7 A–B). When observed under SEM, tubercles showed to be depressions that correspond to the wide top of pillars, surrounded by a epicuticular fold

( Fig. 7C white arrowhead). Faint transverse cuticular folds are visible. Ventrally, the cuticle is finely punctuated (15–16 pillars / 10 µm) ( Figs 6 C–D, 7C black arrowhead).

Rosette-shaped gonopore separated from the anus by a well-defined groove ( Fig. 6C ).

Differential diagnosis

Excluding the new species, there are 26 species of Batillipes with the same toe arrangement pattern on feet of fourth legs as B. lusitanus sp. nov., which has the middle toes (3 and 4) on the fourth feet equal in length. However, only two of those species, B. roscoffensis Kristensen, 1978 and B. adriaticus , have the dorsal cuticular ornamentation, constituted by large pillars (ca 3.0 µm high). Batillipes roscoffensis clearly differs from the new species in having scattered and randomly distributed dots (“small pox” according the terminology of Kristensen 1978). Those dots lack in all the other known Batillipes species and they were described by Kristensen (1978) under TEM (transmission electron microscopy), as elevations (of spongy electron dense mass, see Kristensen 1978: figs 13, 17). Moreover, in B. roscoffensis the caudal apparatus totally lacks and the lateral cirri A is much longer than in B. lusitanus sp. nov. (cirrus A ca 100 µm long, corresponding to 40% of body length in B. roscoffensis , and less than 50 µm long, corresponding to ca 20% of body length in the new species).

Batillipes lusitanus sp. nov. shares with B. adriaticus , the most similar species, the peculiar dorsal cuticle punctation constituted by large pillars, appearing as large tubercles. These two species can be clearly distinguished by the shape of the caudal apparatus that consists in a roundish cuticular expansion in B. lusitanus sp. nov. and in a sharp and long spine in B. adriaticus . The lateral body projection between legs III–IV is also blunt or slightly pointed in the new species while it is sharply pointed in B. adriaticus . Moreover, contrary to B. adriaticus , in the new species, a small rigid process is present in the distal extreme of legs IV and the surface of the primary clava is wrinkled. In addition, although with overlapping values, in adults of B. lusitanus sp. nov. the sensory organ on legs IV is slightly shorter than in B. adriaticus (range: 9–27 µm long in B. lusitanus sp. nov. and 20–40 µm long in B. adriaticus ).

Associated species

Batillipes algharbensis sp. nov., B. pennaki , B. phreaticus and H. greveni .

Remarks

Measurements of structures obtained from specimens of the new species are provided in Table 2. Sexual dimorphism is not evident. Males are similar to females in both qualitative and quantitative characters, except for their circular gonopore with a cuticular crescent shaped fold and located nearer the anus ( Fig. 6D ). Juveniles, with six toes on each leg but without a visible gonopore, are also similar to adults ( Table 2 for morphometrics). In the holotype, ventro-lateral body projections between legs I–III (body projections 2–3, respectively) are indistinct, but in some paratypes, although small, they are visible between all leg pairs ( Fig. 5C ). This variability could be attributed to the effect of microslide preparation highlighted by the ventral position of lateral projections. Among adults, the size and morphology of the caudal apparatus and lateral body projections, especially those between legs III and IV, show some variation, being perfectly semicircular, as in the holotype, or slightly pointed. In four-toed larvae, caudal apparatus and lateral projections are clearly conical.

The variability in shape of lateral projections and caudal apparatus was responsible for the misidentification of three specimens collected in 2011 in Portugal at Memória Beach, Matosinhos, (41°13′49″ N, 8°43′21″ W) ( Rubal et al. 2013b). These specimens were wrongly attributed to B. similis on account of the conical-shaped cuticular projections, evidenced by microslide preparation. A deeper examination showed that the middle toes on legs IV are equal in length and that the cuticle exhibits the

same peculiar pattern of B. lusitanus sp. nov. Therefore, as suggested by Rubal et al. (2016, 2017), the presence of B. similis on the Portuguese coast cannot be assumed.

Figures

Fig. 4. Batillipes lusitanus sp. nov. A. Schematic drawing, dorsal view. B. Habitus of the holotype, ♀, ventral view. Scale bars = 50 µm.

Fig. 5. Batillipes lusitanus sp. nov. A–B, D. Holotype, ♀. A–B. Detail of the head. A. Dorsal view, showing internal cirrus (black arrowhead), lateral cirrus (asterisk), secondary clava (white arrowhead). B. Ventral view, showing primary clava (white arrowhead), external cirrus (black arrowhead). C. Detail of body lateral projections of a paratype (slide C.IX-46) (black arrowheads); D. Detail of leg sensory organ on leg IV. Scale bars = 10 µm.

Fig. 6. Batillipes lusitanus sp. nov. A. Fourth leg of a paratype (slide C.IX-46) with details of toes (1–6), note the shape of the ventro-lateral projection between legs III–IV (black arrowhead). B. Fourth leg of a paratype (slide C.IX-1), showing the rigid process on the distal extreme (black arrowhead). C. Female gonopore (white arrowhead) and anus (black arrowhead). D. Male gonopore (white arrowhead) and anus (black arrowhead). Scale bars = 10 µm.

Fig. 7. Batillipes lusitanus sp. nov. A. Posterior portion of the body, showing the dorsal sculpture. B. Caudal apparatus, showing details of cuticular pillars. C. SEM photo showing the dorsal (white arrowhead) and ventral (black arrowhead) aspect of the cuticle. Pillars are also visible (black arrow). Scale bars = 10 µm.