Dactylobiotus grandipes, the type species of the genus, is redescribed based on the type material. D. grandipes is most similar to D. dispar, D. parthenogeneticus and D. selenicus in the shape of egg processes and the presence of dorso-lateral papillae between legs III and IV, but it differs from these species mainly by morphometric characters of the buccal tube and claws as well as by some egg traits

Kaczmarek, Łukasz

Michalczyk, Łukasz

English

Jagiellonian Univeristy Repository

        Genus                                Vol. 21(1): 155-162                            Wrocław, 30 III 2010Redescription of Dactylobiotus grandipes (SchuSter, toftner & GriGarick, 1978), the type species for the genus Dactylobiotus(Tardigrada: Macrobiotidae)Łukasz kaczmarek1 & Łukasz michalczyk21Department of Animal Taxonomy and Ecology, A. Mickiewicz University, Umultowska 89, 61-614 Poznań, Poland; e-mail: kaczmar@amu.edu.pl2Centre for Ecology, Evolution and Conservation, School of Biological Sciences, University of East Anglia, Norwich NR4 7TJ, UK; e-mail: LM@tardigrada.netabStract. Dactylobiotus grandipes, the type species of the genus, is redescribed based on the type material. D. grandipes is most similar to D. dispar, D. parthenogeneticus and D. selenicus in the shape of egg processes and the presence of dorso-lateral papillae between legs III and IV, but it differs from these species mainly by morphometric characters of the buccal tube and claws as well as by some egg traits.Key words: Tardigrada, taxonomy,  Dactylobiotus grandipes, Macrobiotus  grandipes, rede-scription,.INTRoDUCTIoNDactylobiotus grandipes was described by SchuSter et al. in 1977 as Macrobiotus grandipes. Later, in 1980 SchuSter et al. established the genus Dactylobiotus with Macrobiotus grandipes (SchuSter, toftner & GriGarick, 1978) as the type species. The genus Dactylobiotus is characterised mainly by the presence of the Macrobiotus type buccal tube and claws of the Dactylobiotus type (for more details see SchuSter et al. 1980). D. grandipes was originally described from Lake Tahoe in California (USA) and up to now is known only from the USA (mcinnes 1994). In their paper SchuSter et al. in 1977 described in detail biology and some ecological (especially seasonal) aspects of D. grandipes in Tahoe Lake. They gave also some information about buccal tube morphology (ratio between buccal tube length and length of animal) but the description of the species is very brief and lacks taxonomically important details. Specifically, 156 ŁUKASz KACzMAREK, ŁUKASz MIChALCzyKSchuSter et al. in (1977) did not provide any information on the oral cavity morphology and gave only a brief description of eggs. Moreover, measurements of adults and eggs are very basic (except for the incomplete measurements of the holotype). Since the ShuSter et al. paper many new valuable taxonomic characters have been established and they should be carefully examined in D. grandipes.The genus Dactylobiotus is widespread throughout the world and contains 15 de-scribed species, however the taxonomic position of D. macronyx (DujarDin, 1851) is still unclear and further two species, D. aquatilis yang, 1999 and D. henanensis yang, 2002, are in need of revision since taxonomically important characters have not been provided in the original descriptions (kaczmarek et al. 2008).here, we present a redescription of D. grandipes based on the type material and using modern taxonomy tools. In addition to the description and morphometric data of some new characters we also provide a detailed differential diagnosis with most similar species of the genus Dactylobiotus.MATERIAL AND METhoDSWe examined 46 paratypes (13 specimens, 18 specimens in simplex stage, 11 exuvia with eggs and 4 free eggs) of Dactylobiotus grandipes preserved at The Bohart Museum, Department of Entomology, University of California, Davis, USA. Unfortunately we were unable to examine the holotype.All measurements of D. grandipes are given in micrometers [µm]. Structures were measured only if their orientations were suitable. Body length was measured from the anterior extremity to the end of the body, excluding the hind legs. Buccal tube length and the level of the stylet support insertion point were measured according to Pilato (1981). Buccal tube widths were measured as the external and internal diameters at the level of the stylet support insertion point. Claw lengths were measured according binDa & Pilato (1999). only external claws (anterior in case of claws IV) were measured. The pt ratio is the ratio of the length of a given structure to the length of the buccal tube, expressed as a percentage (Pilato 1981). The oral cavity armature nomenclature adapted after michalczyk & kaczmarek (2003). Photomicrographs were made using phase contrast microscope olympus BX 41.Dactylobiotus grandipes (SchuSter, toftner & GriGarick, 1977)(Figs 1-9)material examined46 paratypes (13 specimens, 18 specimens in simplex stage, 11 exuvia with eggs and 4 free eggs)tyPe localityPope Beach, Lake Tahoe, California (USA)157REDESCRIPTIoN oF Dactylobiotus granDipesDiStributionKnown only from three localities in the USA (California, New hampshire, Ten-nessee).reDeScriptionAdult (for measurements see Table 1): Body yellow, eyes absent (Fig. 1). Cuticle smooth or slightly wrinkled, without gibbosities, spines or defined sculpture (Fig. 2). An oval papilla between legs III and IV on each side of the body is present (Fig. 3).Bucco-pharyngeal apparatus of the Macrobiotus type with ventral lamina and ten peribuccal lamellae (Fig. 4). Peribuccal papulae absent. Mouth antero-ventral. oral cavity armature consisting of only one (i.e. second) band of teeth (Fig. 5). The first and the third band of teeth absent. The second band of teeth is placed in the posterior portion of the oral cavity. The band is continuous and composed of 4-5 irregular rows of small, dense teeth. Teeth in the shape of round or slightly oval granules/cones (spaces between teeth usually as wide as the teeth themselves). The band is continuous and looks the same on all oral cavity walls.CHARACTERN RANGE MEAN SDµm pt µm pt µm ptBody length 9 357.1 – 658.3 570.4 – 830.2 554.8 728.8 117.8 80.0Buccal tube 9 59.4 – 88.8  –  75.6 – 11.8 –Stylet support insertion point 9 43.2 – 63.7 70.6 – 73.8 54.7 72.3 8.7 1.1Buccal tube external width 9 5.7 – 9.2 9.5 – 11.8 7.8 10.4 1.1 0.7Buccal tube internal width 9 3.5 – 5.8 5.9 – 8.8 5.0 6.7 0.7 0.9Ventral lamina length 6 36.3 – 48.5 54.1 – 58.0 45.1 55.7 4.6 1.8Macroplacoid 1 length 9 17.7 – 29.9 29.8 – 34.5 24.2 31.9 4.6 1.9Macroplacoid 2 length 9 10.4 – 19.0 17.0 – 21.4 14.8 19.4 3.1 1.4Macroplacoid row length 9 31.4 – 52.4 52.7 – 59.1 42.1 55.4 7.9 2.5Claw 1 - tc (ext) length 6 33.1 – 48.6 0.0 – 59.3 43.2 46.8 6.1 20.8Claw 1 - sb (ext) length 6 8.3 – 13.5 0.0 – 16.2 11.8 12.8 1.9 5.7Claw 2 - tc (ext) length 6 33.0 – 53.2 55.6 – 63.3 43.9 58.4 9.1 3.5Claw 2 - sb (ext) length 6 9.0 – 17.8 14.7 – 21.2 13.2 17.4 3.7 2.3Claw 3 - tc (ext) length 7 33.2 – 53.2 54.2 – 64.6 48.3 60.3 7.2 3.5Claw 3 - sb (ext) length 7 9.5 – 17.6 15.5 – 21.0 14.9 18.5 2.6 2.0Claw 4 - tc (ext/ant) length 7 45.9 – 74.8 70.7 – 89.2 65.5 82.4 9.7 7.0Claw 4 - sb (ext/ant) length 7 14.7 – 22.5 21.7 – 27.5 20.2 25.4 2.7 2.1Claw 1 - sb/tc length ratio 6 0.25 – 0.31  –  0.27 – 0.03 –Claw 2 - sb/tc length ratio 6 0.26 – 0.33  –  0.30 – 0.03 –Claw 3 - sb/tc length ratio 7 0.28 – 0.33  –  0.31 – 0.02 –Claw 4 - sb/tc length ratio 7 0.30 – 0.32  –  0.31 – 0.01 –Table 1. Measurements [in µm] and pt values of selected morphological structures of specimens of Dacty-lobiotus grandipes (RANGE refers to the smallest and the largest structure found among all measured specimens; N – number of specimens/structures measured, SD – standard deviation).158 ŁUKASz KACzMAREK, ŁUKASz MIChALCzyKAt the end of the buccal tube, triangular pharyngeal apophyses present. Pharyngeal bulb spherical with two rod-shaped macroplacoids, with sharpened edges. Macropla-coids situated very close one to another (Fig. 6). The first macroplacoid longer, with a central constriction, second shorter and with subterminal constriction and terminal projections (i.e. macroplacoid length configuration is 1-2). Microplacoid and septulum absent.Claws of the Dactylobiotus type (configuration 2-1-1-2), similar in size and shape on all legs and with very short basal portions (Fig. 7). Primary branches of claws with small and short accessory points. Lunules are absent, but a robust semilunar cuticular connection between each external and internal claw is present. Claws I-III equal in length, but hind claws clearly larger. Eggs (for measurements see Table 2): Large, laid freely. Spherical or slightly oval, with 52-57 processes on the circumference (Fig. 8). Processes in the shape of short and wide cones (base diameter of each process similar to its height) (Fig. 9). Processes and the surface between them smooth, i.e. no reticulation, granulation or areolation is visible in PCM. CHARACTER N MIN MAX MEAN SDDiameter of egg without processes 4 93.7 105.5 101.5 5.3Diameter of egg with processes 4 99.9 111.2 107.1 5.0Processes height 12 2.3 4.2 3.2 0.6Processes base width 12 1.7 3.2 2.3 0.4Distance between processes 12 1.2 2.6 2.0 0.4Number of processes on the egg circumference 4 50 57 53.0 2.9remarksonly nine specimens of all examined paratypes were measured (the remaining individuals were either in the simplex stage or the orientation of their structures was unsuitable for measurements). Despite all the specimens we examined are clearly yel-low, the original description does not mention body colouration. It is possible that the colour is a side effect of the mounting medium in which specimens were fixed, though given that yellow pigment is found in other Dactylobiotus species (e.g. D. luci) it is very likely that SchuSter et al. (1977) simply ignored this character. The absence of the third band of teeth is very unusual as in all other known species of the genus Dac-tylobiotus the oral cavity armature consists of two bands of teeth (in all the first band of teeth is missing). however, this should be confirmed in a fresh material as in the majority of examined specimens the oral cavity region was not visible well. Moreover, it is possible that although the third band was originally present in the specimens, it is no longer detectable due to the age of the type material (32 years). on the other hand, it is hard to conceive why the third band (normally consisting of large, ridge-shaped Table 2. Measurements [in µm] of selected morphological structures of free eggs of Dactylobiotus grandipes (RANGE refers to the smallest and the largest structure found among all measured eggs; N – number of eggs/structures measured, SD – standard deviation).159REDESCRIPTIoN oF Dactylobiotus granDipesteeth) would disappear while the second band (which consists of small teeth) is still in a good condition.In the original description SchuSter et al. (1977) have drawn dots between egg processes although this character was not mentioned in the text. We did not observe any sculpture, however it is possible that if it was indistinct it could have disappeared with time. Nevertheless, it is also possible that dotting was used by the authors simply to outline the egg surface and does not represent a granular appearance. Again, exa-mination of fresh material should confirm the egg shell appearance.differential diagnosisDactylobiotus grandipes is in the general shape of egg processes and the presence of dorso-lateral papillae most similar to three other known Dactylobiotus species: D. dispar (murray, 1907), D. parthenogeneticus Bertolani, 1981 and D. selenicus Bertolani, 1981.D. grandipes differs from D. dispar mainly by: having egg processes without flexible apices, a higher number of egg processes on the egg circumference (50-57 in D. grandipes and only ca. 35 in D. parthenogeneticus (based on the drawing in binDa 1-3. Dactylobiotus grandipes: 1 – habitus (ventral view), 2 – wrinkles on ventral cuticle, 3 – dorso-lateral papillae between legs III and IV160 ŁUKASz KACzMAREK, ŁUKASz MIChALCzyK4-7. Dactylobiotus grandipes: 4 – buccal apparatus (lateral view), 5 – oral cavity armature consisting of a single band of small teeth, 6 – ventral macroplacoids, 7 – Dactylobiotus grandipes: claws IV161REDESCRIPTIoN oF Dactylobiotus granDipes& Pilato 1999), the absence of the third band of teeth (note that this character needs to be confirmed, see Remarks), the absence of eyes, a longer buccal tube (59.4  in D. grandipes specimen 372.9 long and 51.2 in D. dispar specimen 389.0 long), a narrower buccal tube (5.7  in D. grandipes specimen 372.9 long and 9.1 in D. dispar specimen 389.0 long), a lower pt of the buccal tube width (9.5-11.8 in D. grandipes and 14.4-17.7 in D. dispar), longer claws III (33.0  in D. grandipes specimen 372.9 long and 19.5 in D. dispar specimen 389.0 long), higher pt of claws II-III (54.2-64.6 in D. grandipes and 37.6-43.0 in D. dispar), longer claws IV (45.9 in D. grandipes specimen 372.9 long and 25.0 in D. dispar specimen 389.0 long), a higher pt value of claws IV (70.7-89.2 in D. grandipes and 46.8-54.9 in D. dispar). All measurements are given/calculated according to ramazzotti & maucci (1983) and Binda & Pilato (1999).D. grandipes differs from D. parthenogeneticus mainly by: having slightly shor-ter egg processes and without indentations (2.3-3.7 in D. grandipes and 4.0-4.5 in D. parthenogeneticus), a higher number of egg processes on the egg circumference (50-57 in D. grandipes and ca. 40 in D. parthenogeneticus (based on the drawing in Binda & Pilato 1999), the absence of the third band of teeth (note that this character needs to be confirmed, see Remarks), the absence of eyes, a longer buccal tube (73.9 in D. grandipes specimen 558.6 long and 58.8 in D. parthenogeneticus specimen 8-9. Dactylobiotus grandipes: 8 – egg surface, 9 – egg processes (mid section)162 ŁUKASz KACzMAREK, ŁUKASz MIChALCzyK581.4 long), longer macroplacoids (I = 25.5 (pt = 34.5), II = 13.7 (pt = 18.5) in D. grandipes specimen 558.6 long and I = 16.4 (pt = 27.9), II = 10.6 (pt = 18.0) in D. parthenogeneticus specimen 581.4 long), less evident accessory points, longer claws II-III (33.0-53.2 (pt = 54.2-64.6) in D. grandipes and 13.0-21.5 (pt = 31.2-48.8) in D. parthenogeneticus), much longer claws IV (45.9-74.8 (pt = 70.7-89.2) in D. grandipes and 17.1-27.9 (pt = 41.2-53.2) in D. parthenogeneticus). All measurements are given/calculated according Bertolani (1981) and Binda & Pilato (1999).D. grandipes differs from D. selenicus mainly by: having a different shape of egg processes (wide cones without indentations in D. grandipes and crater-shaped in D. selenicus), the absence of the third band of teeth (note that this character needs to be confirmed, see Remarks), the absence of eyes, a longer buccal tube (73.9 in D. grandipes specimen 558.6 long and 65.7 in D. selenicus specimen 563.0 long), the first macroplacoid with a central constriction, a higher pt of claws IV (70.7-89.2 in D. grandipes and about 59.0 in D. selenicus). All measurements are given and calculated according Bertolani (1981) and Binda & Pilato (1999).acknowledgementsWe would like to thank Dr. steven l. heydon of The Bohart Museum (Department of Entomology, University of California, Davis, USA) for the loan of D. grandipes paratypes.REFERENCESBertolani, r., 1981. A new genus and five new species of Italian fresh-water tardigrades. Boll. Mus. Civ. St. Nat. Verona, 8: 249-254.Binda, m.g., Pilato, g., 1999. Dactylobiotus lombardoi sp. n. (Eutardigrada: Macrobiotidae) from Tierra del Fuego, with a key to the Dactylobiotus-species. zool. Anz., 238: 147–155.kaczmarek, Ł., michalczyk, Ł., eggermont, h., 2008. Dactylobiotus luci, a new freshwater tardigrade (Eutardigrada: Macrobiotidae) from the Ruwenzori Mountains, Uganda. Afr. zool., 43: 150-155.mcinnes, s.J., 1994. zoogeographic distribution of terrestrial/freshwater tardigrades from current literature. Jour. Nat. hist., 28: 257–352.Pilato, g., 1981. Analisi di nuovi caratteri nello studio degli Eutardigradi. Animalia, 8: 51–57.ramazzotti, g., maucci, w., 1983. Il Phylum Tardigrada. Mem. dell’Ist. Ital. di Idrobiolo., Pallanz,a 41: 1-1012.schuster, r.o., toftner, e.c., grigarick, a.a., 1977. Tardigrada of Pope Beach, Lake Tahoe, California. Wasm. Jour. of Biol., 35(1): 115-136.schuster, r.o., nelson, d.r., grigarick, a.a., christenBerry, D., 1980 Systematic criteria of the Eutardigrada. Trans. Amer. Microsc. Soc., 99(3): 284-303.

Redescription of Dactylobiotus grandipes (SCHUSTER, TOFTNER & GRIGARICK, 1978), the type species for the genus Dactylobiotus (Tardigrada : Macrobiotidae)

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Redescription of Dactylobiotus grandipes (SCHUSTER, TOFTNER & GRIGARICK, 1978), the type species for the genus Dactylobiotus (Tardigrada : Macrobiotidae)

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