Macrobiotus alvaroi, Pilato & Kaczmarek, 2007

Pilato, Giovanni & Kaczmarek, Łukasz, 2007, Macrobiotus alvaroi, a new species of eutardigrade (Tardigrada, Macrobiotidae) of the polyopus group from Costa Rica (Central America), Zootaxa 1479 (1), pp. 1-7 : 2-6

Macrobiotus alvaroi sp. n.

( Fig. 1 , Fig. 2G, H )

= Macrobiotus polyopus Kaczmarek, 2003

Material examined: 8 specimens and 6 eggs (one egg with embryo), additional material examined: 2 specimens and 3 eggs.

Species diagnosis: cuticle smooth with circular and elliptical pores, without dots on the legs; eye spots present; ventral lamina longer than the double length of the stylet sheaths; buccal armature with peribuccal lamellae and a system of very thin transversal ridges (three dorsal and three ventral); pharyngeal bulb with apophyses, two rod-shaped macroplacoids and a small microplacoid; claws of hufelandi type (the common basal portion short); smooth lunules present; eggs, laid freely, with 23–26 small processes around the circumference and about 100 in the hemisphere; egg processes with a basal portion in shape of a hexagonal prism and a conical distal portion with an apical, sharpened, point with almost invisible annulations; egg shell with a regular reticular design with hexagonal meshes.

Description of the holotype: Body length 290.0, colourless, eye spots present, cuticle smooth with circular and elliptical pores. Granulation on the legs absent.

Mouth opening terminal with 10 small peribuccal lamellae, buccal armature very simple and difficult to see due to the small dimensions of the buccal cavity; system of very thin transversal ridges visible (three dor- sal and three ventral; medioventral ridge very short). Buccal tube 30.8 long and 3.1 wide [10.1] ( Fig. 1A, B ); ventral lamina 19.1 [62.0] long (longer than the double length of the stylet sheaths). Stylet supports inserted on the buccal tube at 72.9 % of its length. Large thickening, to which the pharyngeal apophyses are connected, present at the end of the buccal tube.

Pharyngeal bulb ( Fig. 1B ) with apophyses, two rod-shaped macroplacoids and a small microplacoid. First macroplacoid with a central constriction, 7.1 [23.1] long, second one shorter 4.7 [15.2] long. Microplacoid small, 1.6 [5.2] long. Entire placoid row 14.7 [47.7] long, macroplacoid row 12.7 [41.2].

Claws of hufelandi type, short (particularly the common basal portion) but not weak ( Fig.1C ); internal and external claws of the second and third pairs of legs 7.6 [24.7] and 8.0 [26.0] long respectively; anterior and posterior claws of the fourth pair of legs 8.5 [27.6] and 8.7 [28.2] long respectively. Main branches of claws with well developed accessory points. Small, smooth, lunules present on all legs. Two faint cuticular thickenings, difficult to see, present near the lunules on the first three pairs of legs.

The paratypes are similar to the holotype in both qualitative and metric characters; the dimensions of some structures of the smallest and of the largest measured specimens are given in Table 1.

Eggs laid freely. Spherical, with large number of small processes ( Fig. 1D, E ; Fig. 2G, H ) (23-26 around the circumference, about 100 in the hemisphere) with basal portion in shape of hexagonal prism. Distal portion of processes conical with apical, sharpened, point and with almost invisible annulations. The base of the processes are joined to one another by thin striae forming a very regular reticular design with hexagonal meshes. Egg shell (excluding reticular design) smooth. Measurements of some structures of the eggs are given in Table 2.

Type locality: Central America, Costa Rica, Heredia Province, ‘ La Selva’ Biological Station , moss from the tropical wet forest, August 2000, leg. Ziemowit Olszanowski.

Additional material: Central America, Costa Rica, Alajuela Province, moss sample was collected from stone near the road from La Tigra to Ciudad Quesada (San Carlos) 16.0 km before Ciudad Quesada , 10 January 2003, leg. Łukasz Kaczmarek.

Type depositories: Holotype (slide N. 5100), 5 paratypes and one egg are deposited in the collection of Binda & Pilato ( Department of Animal Biology " Marcello La Greca " University of Catania ); 2 paratypes 5 eggs and also additional material are deposited at the Department of Animal Taxonomy and Ecology, A. Mickiewicz University, Pozna ṅ, Poland.

Etymology: The new species is dedicated to the great Costa Rican zoologist and coordinator in National Biodiversity Institute ( INBio) Dr. Alvaro Herrera V.

Differential diagnosis.

M. alvaroi sp. n. differs from M. polyopus in the following features: buccal tube with a longer ventral lamina; microplacoid present; claws not particularly weak and with accessory points not particularly thin; in some characters of the eggs ( Table 3): processes smaller and more numerous (25 around the circumference and about 100 in the hemisphere in M. alvaroi sp. n. and 18 and 39 respectively in M. polyopus ).

The new species differs from M. mandalaae in lacking granulation on the legs IV, and in some characters of the eggs: processes more numerous (about 100 in the hemisphere in M. alvaroi sp. n. and 70–75 in M. mandalaae ) and slightly more spaced, with a thinner and more sharpened distal portion; processes never bifurcated, with annulations very difficult to see ( Fig. 2G, H and E, F , see also Table 3).

*from the drawing of Marcus (1928).

M. alvaroi sp. n differs from M. insularis in having shorter and narrower buccal tube. Due to the different length of the buccal tube, some structures, e.g., the placoids and the claws, have different values of the pt index (see Table 4). It also differs in some characters of the eggs ( Fig. 2G, H and A, B ): smaller dimensions (diameter without processes 53.3–58.7 and 62.2–70.0 including them in M.alvaroi sp. n., about 80 and 94.0 respectively in M. insularis ), smaller processes (3.6–6.1 high in M. alvaroi sp. n. and 7.3–8.8 in M. insularis ), more numerous processes (23–26 in the circumference and about 100 in the hemisphere of M. alvaroi sp. n. and 13–14 and 35 respectively in M. insularis ), processes different in the shape, egg shell with reticular design and without dots.

Besides, the new species differs from M. ocotensis in lacking granulation on the legs and in some characters of the eggs ( Table 3; Fig 2G, H and C, D ): slightly smaller dimensions (diameter 53.3–58.7 excluding processes and 62.2–70.0 including them in M. alvaroi sp. n., about 63.0 and about 80.0 respectively in M. ocotensis ); processes different in the shape (basal portion in shape of a hexagonal prism and conical distal portion with an apical, sharpened point with faint annulations in M. alvaroi sp. n., and in M. ocotensis basal portion in the shape of a hexagonal prism and a breast-shaped distal portion with an apical, sharpened point without annulations).

Figures

FIGURE 1. Macrobiotus alvaroi sp. n. A–B, buccopharyngeal apparatus (holotype). C, claws of the second and third pairs of legs. D, egg (the reticular design of the egg shell is focused). E, detail of the egg (the shape of the egg processes is visible). Scale bar = 10 µm.

FIGURE 2. Eggs, and their details, of: A–B, M. insularis. C–D, M. ocotensis. E–F, M. mandalae. G–H, M. alvaroi sp. n. Scale bar = 10 µm.