Batillipes Richters 1909
Creators: name: Santos, Erika
name: Rubal, Marcos
name: Veiga, Puri
name: da Rocha, Clélia M. C.
name: Fontoura, Paulo
Publisher: name: Zenodo
Year: 2018
Subjects: Biodiversity
Taxonomy
Animalia
Tardigrada
Heterotardigrada
Arthrotardigrada
Batillipedidae
Batillipes

description: A dichotomous key to the identification of species of Batillipes
Traditionally, keys to the identification of species of Batillipes used the caudal apparatus (e.g., Ramazzotti & Maucci 1983) as the main distinguishing trait. However, after the discussion of the variability of taxonomic characters within the genus (McKirdy 1975; Gallo D’Addabbo et al. 2000), this trait, unless peculiar for some species or when combined with other characters, is no longer valid. Recently, a comprehensive key to all known species of Batillipes was published by Menechella et al. (2017). This key used the toe arrangement pattern, suggested by Kristensen & Mackness (2000), as the first differentiating character. However, this key is no longer practical on account of the inaccuracies on the definition of toe patterns referred to in the present study. Therefore, a new key is provided, using a new proposal of toe arrangement patterns, shape of primary clava, ventral body projections between legs III–IV and details of cuticular sculpture as main taxonomic characters, allowing an easier identification based on observations under light microscopy (particularly PCM or DIC).
The shape and development of lateral body projections, as well as the relative size of leg sensory organs, also secondarily considered in the key, are ontogenetically variable characters (Villora-Moreno & de Zio Grimaldi 1993; Gallo D’Addabbo et al. 2000), for this reason only adult specimens should be identified using the proposed key and more than one character should be used.
For a more accurate identification of some species, several characters are given in the last identification step. Unfortunately, for some old described species, some reliable attributes are unknown (e.g., details of punctation) and its presence/ absence cannot be assumed, making the construction of identification keys for species of Batillipes an ongoing process.
Given that B. tubernatis Pollock, 1971 and B. crassipes Tchesunov & Mokievsky, 1995 were the object of very different redescriptions, by McKirdy (1975) and Rho et al. (1999), respectively, different options of identification are provided in this key.
Dichotomous key
1. Middle toes (3 and 4) on feet of legs IV equal in length (considering toe 1 the most cephalically) (species group A) ..................................................................................................................................... 2
– Middle toes (3 and 4) on feet of legs IV of different lengths (species groups B and C) ................ 29
2. Primary clavae divided into two or more parts ................................................................................. 3
– Primary clavae undivided ................................................................................................................. 6
3. Primary clavae divided into two portions by a constriction ............................................................. 4
– Primary clavae divided into 6 portions by four constrictions .................. B. annulatus de Zio, 1962
4 Well developed lateral body projections between legs III and IV; caudal spine present and inserted on a basal support; folds on dorsal cuticle barely visible or indistinct ............................................. 5
– Lateral body projections slight; caudal spine inserted directly on body cuticle; marked dorsal cuticular folds, appearing as segmental plates ...................................... B. gilmartini McGinty, 1969
5 Body projections between legs III and IV lobate-shaped with rounded contour, primary clavae with two parts almost identical and markedly separated by a deep incision. Femur of legs IV very broad and short ..................................................................................................... B. pennaki Marcus, 1946
– Body projections between legs III and IV are large and conical with a terminal portion sometimes spike-shaped; primary clavae with two different parts, the first one stiff and the second slightly wrinkled. Femur on legs IV not particularly broad and short, appearing as typical of the majority of Batillipes species ................... B. spinicauda Gallo D’Addabbo, Sandulli & de Zio Grimaldi, 2005
6. Dorsal cuticle, with or without scattered and randomly distributed larger dots, constituted of uniformly distributed large pillars (ca 5–7 pillars / 10 µm, each 3 µm high) that can appear as large tubercles (diameter ca 3 µm) ............................................................................................................ 7
– Dorsal cuticle with a different aspect, constituted of the typical Batillipes fine punctation (more than 8–10 pillars / 10 µm, each less than 1.5 µm high). Dorsal punctation can be uniformly distributed, or it can have simultaneously apunctate areas, finely punctated areas and areas with more roughly punctuation ....................................................................................................................................... 9
7. Dorsal cuticle roughly sculptured with scattered and randomly distributed larger dots (like “smallpox” in the terminology of Kristensen 1978). Caudal apparatus absent and replaced by a small groove; cephalic appendages very long (cirrus A ca 100 µm long, corresponding to 40% of body length); toes with elongated elliptical suction discs with a cut terminal edge .................................... ......................................................................................................... B. roscoffensis Kristensen, 1978
– Dorsal cuticle without scattered dots, sculptured by uniformly distributed dorsal pillars, appearing as large tubercles (diameter ca 3 µm). Caudal apparatus present; cephalic appendages not particularly long (cirrus A less than 50 µm long, corresponding to ca 20–28% of body length); toes with circular to ovoid suction discs ........................................................................................................................ 8
8. Lateral body projections between legs III and IV conical and sharply pointed; the caudal apparatus consists of a sharp and long spine inserted on cylindrical base (occasionally the caudal spine is bifid or could have accessory points at the base). Processes on the lateral surface of legs IV absent ........ B. adriaticus Grimaldi de Zio, Morone De Lucia, D’Addabbo Gallo & Grimaldi, 1979
– Lateral body projections between legs III–IV blunt or slightly pointed; the caudal apparatus is a roundish cuticular expansion. A small rigid process is present on the lateral surface of legs IV ....................................................................................................................... B. lusitanus sp. nov.
9. Well developed and conspicuous wing-shaped body projections between legs III and IV ............ 10
– Body projections between legs III and IV absent or reduced to short protuberances, papillae, spines or tooth-shaped ............................................................................................................................... 15
10. Body projections between legs III and IV with a rounded contour .................................................11
– Body projections between legs III and IV conical with one or two sharp points ........................... 23
11. Caudal apparatus consists of one or two spine-shaped appendages ............................................... 12
– Caudal apparatus indistinct or consisting of a more or less prominent blunt projection ................ 14
12. Femur of legs IV very broad and short. Body box-shaped; middle toes (3 and 4) on feet of legs IV very short (so short that suction discs resemble sessile); caudal apparatus consists of a spine barely protruding beyond edge of the body and inserted on a basal support; indistinct secondary clavae ......................................................................................... B. crassipes (sensu Rho et al. 1999)
– Femur of legs IV not particularly broad and short as typical of the majority of species of Batillipes. Worm-like body with marked transversal cuticular folds; middle toes (3 and 4) on feet of legs IV, although shorter than the other digits, with well-developed stalks; caudal apparatus consists of one or two spines directly inserted on body cuticle; visible secondary clavae ..................................... 13
13. Caudal apparatus consists of two spines (occasionally none); sensory organ on leg I turning frontwards, a pseudo-papilla is present in the transitional zone between the proximal and distal part of the legs ........................................................................................ B. noerrevangi Kristensen, 1978
– Caudal apparatus consists of a single large spine; sensory organ on leg I turning backwards; pseudopapillae on legs absent ................................ B. minius Rubal, Veiga, Fontoura & Sousa-Pinto, 2017
14. Lateral cirri and internal cephalic cirri with terminal tufts; concave and elongated lens-shaped secondary clavae (13 µm wide); sharp pointed lateral processes between legs I–II, blunt between legs II–III; blunt and indistinct caudal apparatus; toes with ovoid suction discs; scapular region not protruding laterally at the level of the first pair of legs ...................................................................... ...................................................... B. solitarius Jørgensen, Boesgaard, Møbjerg & Kristensen, 2014
– Plain tipped lateral and internal cephalic cirri; papillary (3–6 µm wide) or indistinct secondary clava; blunt lateral processes between all leg pairs; caudal apparatus consists of a prominent semicircular projection; toes with spatula-like suction discs; scapular region well developed, protruding laterally at the level of the first pair of legs .................................................................................................. 15
15. Sharply pointed cephalic cirri; secondary clavae indistinct; sensory organs on leg I shorter than sensory organs on leg IV that are spike-shaped; medial toes (3, 4) and external toes (1, 6) on feet of legs IV similar in length ................................................... B. rotundiculus Rho, Min & Chang, 1999
– Cephalic cirri with swollen tips; papillary secondary clavae (3–6 µm wide); sensory organs on leg I longer than sensory organs on leg IV that are clearly divided into two portions, the distal portion with swollen tip; medial toes (3 and 4) on feet of legs IV much shorter than external toes (1, 6) .................................................. B. potiguarensis Santos, da Rocha, Gomes Jr. & Fontoura, 2017
16. Caudal apparatus consists of a spine inserted on a basal support ................................................... 17
– Caudal apparatus absent or, if present, with a different constitution, consisting of a pointed triangular appendage or one or two caudal spines but, in this case, directly inserted on body cuticle and never inserted on a basal support .............................................................................................................. 18
17. Femur of legs IV very broad and short. Middle toes (3 and 4) on feet of legs IV very short (so short that suction discs resemble sessile); projections between legs III and IV absent (very small projections can be present in females); caudal apparatus consists of a short spine barely protruding beyond the edge of the body; very short sensory organs on legs IV .................................................. ........................................................................... B. crassipes Tchesunov & Mokievsky, 1995 (s. str.)
– Femur of legs IV not particularly broad and short as typical of the majority of Batillipes species. Middle toes (3 and 4) on feet of legs IV although shorter than the other digits with well visible stalks; projections between legs III and IV in the shape of small tooth; caudal apparatus consists of a long spine reaching the level of toes of legs IV; very long sensory organs on legs IV also reaching the level of toes of legs IV .............................................................................. B. carnonensis Fize, 1957
18. Caudal apparatus absent ................................................................................................................. 19 – Caudal apparatus present ................................................................................................................ 21
19. Primary clavae much shorter than lateral cirri A ............................................................................ 20
– Primary clavae and lateral cirri A similar in length ............................................................................ ....................................................................... B. amblypyge Menechella, Bulnes & Cazzaniga, 2017
20. Cephalic appendages long (lateral cirri A ca 14% of body length); sensory organ on leg IV very long (ca 14% of body length), reaching, at least, the level of middle toes ................................................. ................................................................................................. B. longispinosus Chang & Rho, 1997
– Cephalic appendages short (lateral cirri A ca 9% of body length); sensory organ on leg IV very short (ca 4% of body length) ........................................................................... B. acaudatus Pollock, 1971
21. Body with the ventro-lateral region between legs III and IV much swollen; caudal apparatus consists of a cuticular conical projection; prominent lateral body projections between the three first leg pairs are present .............................................................................. B. philippinensis Chang & Rho, 1997
– Body box-shaped without the ventro-lateral region between legs III and IV particularly swollen; caudal appendage is a spine (occasionally absent) directly inserted on body cuticle; lateral body projections between legs reduced or absent .................................................................................... 22
22. Large sized (the largest within the genus, 400–600 µm in adult specimens); toes with large elliptical suction discs (ca 4 µm wide and 6 µm long); Projection between legs III–IV, if present, is a short spine .............................................................................................................. B. mirus Richters, 1909
– Small sized Batillipes (ca 160 µm); toes with small roundish suction discs. Projection between legs III–IV indistinct ............................................................................................. B. caudatus Hay, 1917
23. Paired sharply-pointed body projections between legs III and IV; lateral surface of legs IV with a prominent rigid spike (in addition to the long sensory organ); caudal apparatus consists of a twopointed appendage ................................................................................. B. tridentatus Pollock, 1989
– Single conical body projections between legs III and IV; spike on legs IV absent (a small papilla can be present); caudal apparatus consists of one-, two- or multi-pointed appendage ......................... 24
24. Caudal apparatus absent (the terminal edge of the body is flattened) ................................................ ........................................................................................................ B. orientalis Chang & Rho, 1997
– Caudal apparatus present ................................................................................................................ 25
25. Caudal apparatus consists of a single spine, terminating in a sharp point or in a swollen balloon-like structure .......................................................................................................................................... 26
– Caudal apparatus consists of a two-pointed or multi-pointed appendage, in this case constituted by one major pointed spine surrounded, at its base, by a crown of small accessory spines ................ 28
26. Caudal apparatus consists of a long vertical spine, terminating in a swollen balloon-like structure (this structure is occasionally absent); cephalic cirri (except external cirri) frayed (generally trifid) ............................................................................ B. bullacaudatus McGinty & Higgins, 1968
– Caudal apparatus consists of a sharp spine directed backwards; cephalic cirri with lance-like tips ................................................................................................................................................... 27
27. Head with tongue-like projections behind the common pedestals bearing primary clavae and lateral cirri A; sensory organ on leg IV very long (ca 25% of body length), longer than legs IV; dorsal cuticle uniformly punctated (8–10 pillars / 10 µm); papillae on legs absent; caudal spine inserted directly on body cuticle ............................... B. lingularum Menechella, Bulnes & Cazzaniga, 2017
– Head without tongue-like projections behind the common pedestals bearing primary clavae and lateral cirri A; sensory organ on leg IV short (ca 10% of body length), shorter than legs IV; dorsal cuticle not uniformly punctated, it is finely punctated in the dorsal medial region (about 14 pillars / 10 µm) and more roughly (ca 10 pillars / 10 µm) in dorsal margins of the body, head and caudal regions; papillae on legs present; caudal spine inserted on a basal support ......................... B. marcelli Morone De Lucia, D’Addabbo Gallo & Grimaldi de Zio, 1988
28. Caudal apparatus constituted by a one major sharp spine surrounded, at its base, by a crown of small accessory spines; surface of primary clavae with black punctations .................................................. .................................................................................................. B. phreaticus Renaud-Debyser, 1959
– Caudal apparatus constituted by a two-pointed appendage without basal accessory spines; black punctations on primary clavae not observed ....................................... B. dicrocercus Pollock, 1970
29. On feet of legs IV, the middle toe 3 is shorter than the middle toe 4 (Group C and B, subgroup B1) ................................................................................................................................................... 30
– On feet of legs IV, the middle toe 3 is longer than the middle toe 4 (Group B, subgroup B2) ....... 37
30. On feet of legs IV, toes 2 and 5 are the longest and middle toes 3 and 4 are shorter (or similar) than lateral toes 1 and 6, which are of intermediate length (subgroup B1). Primary clavae shorter than lateral cirri A ................................................................................................................................... 31
– On feet of legs IV, toes 2 and 5 are the longest and middle toes 3 and 4 are much longer than lateral toes 1 and 6, which are the shortest (Group C). Primary clavae longer than lateral cirri A ................................................................... B. acuticauda Menechella, Bulnes & Cazzaniga, 2015
31. Lateral body projections between legs absent (in one species, B. friaufi, a very small papilla, less than 5.0 µm, is occasionally present between legs III and IV) ....................................................... 32
– Prominent lateral body projections, especially between legs III and IV (longer than 10.0 µm), present ............................................................................................................................................. 34
32. Caudal apparatus consists of a pointed single triangular appendage more or less elongate (occasionally absent), exhibiting variability in shape and size among specimens; sensory organs II and III without annulated bases; dorsal cuticle uniformly punctated ...................................................................... 33
– Caudal apparatus consists of a trifurcate caudal appendage with lateral spikes shorter than central spike; leg sensory organs II and III with annulated bases; dorsal cuticle with small apunctate areas ............................................................................................................... B. friaufi Riggin, 1962
33. Scapular region with a conspicuous dorsal blunt enlargement; sensory organs on legs I spine-like, inserted in the posterior region of the legs and turned frontwards; sensory organs on legs III long (range 10.0– 11.2 µm in adults 127–225 µm long); tibial papilla on legs absent .................................................. B. dandarae Santos, da Rocha, Gomes Jr. & Fontoura, 2017
– Scapular region not enlarged; sensory organs on legs I articulated, straight and parallel to the toes; sensory organs on legs III short (range 5.0–7.0 µm in adults 122–212 µm long); tibial papilla on legs present ........................ B. africanus Morone De Lucia, D’Addabbo Gallo & Grimaldi de Zio, 1988
34. Caudal apparatus consisting of an ala-like structure often covered with detritus, exhibiting great variability (simple, bilobed, highly furcate); lateral body projections between legs III and IV with more than one point ........................................................................................................................ 35
– Caudal apparatus consisting of a broad-based spiky process, sharpening distally or of a single conical /triangular-shaped process; lateral body projections between legs III and IV with single point ................................................................................................................................................ 36
35. Lateral body projections between legs III and IV two-pointed (in adults); external cephalic cirri horn-shaped; sensory organ on legs IV long (ca 20% of body length); cuticular projections on legs absent ................................................................................... B. lesteri Kristensen & Mackness, 2000
– Lateral body projections between legs III and IV with fringed distal edge (usually more than two blunt fringes); external cephalic cirri terminated by a swollen tip; sensory organ on legs IV much short (ca 10% of body length); small semicircular cuticular projections present on the coxal region of legs I–III ...................................... B. brasiliensis Santos, da Rocha, Gomes Jr. & Fontoura, 2017
36. Caudal apparatus consists of a three pointed spiky process. Primary clavae uniformly tubular; legs IV with a lateral sharp tooth ....................................................... B. littoralis Renaud-Debyser, 1959
– Caudal apparatus consists of a single conical projection. Primary clavae drumstick-like; lateral tooth on legs IV absent ............................................................................................ B. similis Schulz, 1955
37. Lateral body projections between all pairs of legs absent. Tube-shaped primary clavae and indistinct secondary clavae; dorsal cuticle uniformly finely punctated (ca 15 pillars / 10 µm) or exhibiting simultaneously apunctate areas, finely punctated areas and areas with more roughly punctuation ... ......................................................................................................................................................... 38
– Blunt lateral body projections between all leg pairs (small between legs I–III, very well-developed between legsIII–IV).Very thin sharp-pointed primary clavae and strongly developed secondary clavae; dorsal cuticle uniformly coarsely punctated (ca 9–10 pillars / 10 µm) ........ B. algharbensis sp. nov.
38. Caudal region is always swollen and rounded; dorsal cuticle uniformly finely punctuated (ca 14–15 pillars / 10 µm); toe discs ovoid and not indented on the distal edge; dorsal leg papillae absent .......................................................................................... B. tubernatis Pollock, 1971 (s. str.)
– Caudal region usually (ca 80% of the specimens) with a strong swollen-based caudal spike (ca 20% of the specimens without caudal appendage and a few with a small off-center caudal spur); dorsal cuticle not uniformly punctated (dorsolateral and cephalic punctations larger, ca 9 pillars / 10 µm, than in the other dorsal zones, ca 15 pillars / 10 µm that also have 7 transversal apunctate areas); toe discs quadrate with a slightly indented distal edge; dorsal leg papilla present .................................. ................................................................................................... B. tubernatis (sensu McKirdy 1975)
description: Published as part of 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, pp. 1-32 in European Journal of Taxonomy 425 on pages 23-28, DOI: 10.5852/ejt.2018.425, http://zenodo.org/record/3806131