Macrobiotus huziori, Michalczyk & Kaczmarek, 2006

Michalczyk, Łukasz & Kaczmarek, Łukasz, 2006, Macrobiotus huziori, a new species of Tardigrada (Eutardigrada: Macrobiotidae) from Costa Rica (Central America), Zootaxa 1169, pp. 47-59 : 48-58

Macrobiotus huziori sp. nov. ( Figs. 1–5 , 7–43 )

Material examined. 8 adults, 1 infant and 20 eggs (prepared for both, DIC and SEM) from the type locality and from Cartago ( Costa Rica; near the road from Pacayas to Turrialba, 27.5 km before Turrialba; moss from soil; 17.12.2002; leg. Ł. Kaczmarek) .

Description. Adult (measurements of the holotype): Body length 455.0 ( Fig. 1 , see also Fig. 2 ). Body transparent/white, eyes present. Cuticle smooth and without pores. Fine but evident, regular granulation present on all legs but developed better on IV pair ( Figs. 10–11 ). Granules have a complex structure and with SEM they are visible as aggregations of small granules or cones (2 to 10 granules/cones on each aggregation) ( Fig. 11 ).

Bucco­pharyngeal apparatus of Macrobiotus type ( Figs. 3–5 ). Mouth antero­ventral, surrounded by ring of 10 peribuccal lamellae. Oral cavity armature with three bands of teeth ( Figs. 3–4 ). Teeth of first band are smaller than those of the other two bands and are in the shape of small cones/granules. They are present in anterior portion of oral cavity just behind peribuccal lamellae and on them. This band of teeth is continuous and looks the same on all oral cavity walls. The teeth of the second band are intermediate in size between those of the first band and those of the third band of teeth. They are in the shape of small ridges parallel to the main axis of the buccal tube (ventral teeth are little larger than dorsal). They are positioned in the posterior portion of the oral cavity just behind the ring fold and just before the third band of teeth. The second band of teeth is continuous and arranged in one row. Some of the teeth are uniform and regular, in the shape of ridges but the rest are joined one­by­one. Joined teeth are H­, V­ and W­shaped. The teeth of the third band are larger than those in the other two bands and there are usually six. They are in the shape of transverse ridges/baffles. Teeth in this band are positioned in the rear of the oral cavity just behind the second band of teeth and just before the buccal tube opening. Usually this band is not continuous and is divided into two series: ventral and dorsal. Both series consist of one median and two lateral teeth. Dorsal teeth are more bar­shaped and ventral are more rectangular shaped. Medio­ventral tooth is very often divided into 2–5 smaller teeth.

Buccal tube 54.0 long and 12.0 [22.2] wide with one bend in anterior part of tube (visible in lateral view). Stylet supports inserted on buccal tube at 42.0 [77.8]. Pharyngeal bulb slightly oval with apophyses and three macroplacoids ( Figs. 3, 5 ). Pharyngeal apophyses distinct, triangular, wider and indented posteriorly. First macroplacoid thinner anteriorly, 9.0 [16.7] long, second oval or rectangular 7.0 [13.0] long, both without constriction (second microplacoid may sometimes have slight constriction in anterior part). Third macroplacoid 12.0 [22.2] long, with constriction in subterminal part. Microplacoid absent, but there are faint cuticular match­like structures growing out of the posterior ends of the third macroplacoids ( Fig. 6 , visible also on Figs. 1–5 ). These matchlike structures are slightly wider in their terminal parts (see also ‘Differential diagnosis’). Macroplacoid row 31.5 [58.3] long.

Claws of hufelandi type, slender with very narrow bases ( Figs. 8–10 ). Primary branches with distinct accessory points. Lunules on all legs smooth, better developed on IV pair of legs. Primary branch of external claw (pb) of II pair of legs 13.0 [24.1] long, secondary branch (sb) 10.0 [18.5] long; III pb 13.0 [24.1], sb 10.0 [18.5]; IV pb 16.0 [29.6], sb 12.0 [22.2]. Bars on legs absent but cuticular thickenings below claws present ( Fig. 8 ).

Eggs. White, laid freely ( Figs. 12–21 , see also Fig. 2 ). Spherical, areolated, with 9–11 processes on circumference. Processes generally in the shape of cones, elongated in terminal part, however the shape is highly variable ( Figs. 24–36 , see also Figs. 12–21 ). The elongated terminal part may be missing or be thin and long or split in the end. If the terminal part is present it is usually covered by irregular tubercles ( Figs. 30–32 and 34– 36). Processes consist of double wall with transverse supporting walls forming ‘cells’ visible in DIC as a dense reticular design (‘reticulation’ slightly elongated vertically) ( Figs. 22–23 ). External walls of processes smooth or slightly wrinkled (wrinkles in form of rings around a process), without pores. Internal walls strongly porous (visible in SEM only). Surface between processes areolated. Areolation complex ( Figs. 37–44 ). Areolae in the shape of holes which branch into smaller holes closer to the egg surface (see Figs. 43– 44 and 37–38 ). This kind of areolation has not been described so far.

(DIC, scale on 23 same as on 22).

Remarks. Adults: Results of simple statistical analysis of measurements and pt values of selected morphological structures for six specimens are given in Table 1 . Eggs: Statistics for all measurable eggs are provided in Table 2 .

Type locality. Costa Rica, Cartago Province, slope of the Irazu Volcano; Irazu Volcano National Park ; moss from a tree; ca. 3400 m a.s.l.; 17.12.2002; leg. Ł. Kaczmarek.

Type depositories. Holotype and 16 paratypes (6 adults, 1 infant hatching out of egg and 9 eggs) are deposited in the Natural History Collections, Faculty of Biology , A. Mickiewicz University, Umultowska 89, 61–614 Poznań, Poland.

Etymology. The new species was named after the first author’s dear friend Paweł ‘ ihs ’ Huzior.

Differential diagnosis. The eggs of Macrobiotus huziori sp. nov. have a unique, never described before, type of multi­level areolation ( Figs. 37–44 ) unlike other species’ eggs which have areolation in the form of ovals or polygons with just one bottom (‘one level’ areolation). This character excludes the new species from any of the known species groups within the genus Macrobiotus (like the areolatus group, for example) and makes M. huziori sp. nov. easily distinguishable from all the known species. However, the adults of the new species are similar to Macrobiotus areolatus Murray , Macrobiotus crenatus Maucci, 1991 , Macrobiotus csotiensis Iharos, 1966 and species of the Macrobiotus richtersi group. Also the eggs of these species (except for M. csotiensis ) are similar to the eggs of M. huziori sp. nov. with the respect to the conical shape of the processes and the presence of areolation between the processes.

Adults of M. huziori sp. nov. are similar to adults of M. areolatus , M. crenatus and M. csotiensis by the presence of three rod­like macroplacoids and lack of the microplacoid. However, the adults of the new species differ from M. crenatus and M. areolatus by the absence of teeth on the lunulae of IV pair of legs. Due to the poor description of M. csotiensis we were unable to find any differences in the adult morphology, but the eggs of M. csotiensis are very different from the eggs of the new species (hemispherical ornamentations positioned very near to each other covered with a hyaline layer, which is concaved between the processes) ( Iharos 1966). Additionally M. huziori sp. nov. has larger eggs than M. areolatus (80.0–100.0 in M. areolatus and 120.0–160.0 in the new species) ( Ramazzotti & Maucci 1983).

It is also worth noting that the match­like structures growing out of the third macroplacoids in M. huziori sp. nov. and in M. areolatus terminate where the microplacoid is placed in the species of the Macrobiotus richtersi group (see Figs. 6–7 ). In the richtersi group the microplacoid is connected with the third macroplacoid by a thin cuticular yarn­like structure. This, and also similarity in the buccal apparatus structure and the egg shell appearance may suggest that both M. huziori sp. nov. and M. areolatus are closely related to the richtersi group but have probably lost the microplacoids and the match­like structures are the microplacoids remnants.

Figures

FIGURES 1–2. Macrobiotus huziori sp. nov. 1, habitus (adult); 2, hatching infant. (DIC).

FIGURES 3–5. Macrobiotus huziori sp. nov. buccal apparatus. 3, ventral view (note ventral teeth of the bands I–III); 4, mid section (note dorsal teeth of the second and third band); 5, dorsal view. (DIC, scale on 4–5 same as on 3)

FIGURES 6–7. 6, Macrobiotus huziori sp. nov. Third macroplacoids and the remnant microplacoids; 7, Macrobiotus sp. richtersi group, third macroplacoids, microplacoids and yarnlike cuticular structures connecting third macroplacoids with microplacoids. (DIC, scale on 7 same as on 6).

FIGURES 8–11. Macrobiotus huziori sp. nov. 8, claws of the I pair of legs; 9, claws of the III pair of legs; 10, claws of the III pair of legs and granulation; 11, granulation in higher magnification (note that each granule consists of several smaller granules/cones. (8–9, DIC; 10–11, SEM).

FIGURES 12–15. Macrobiotus huziori sp. nov. eggs. (DIC, scale on 13–15 same as on 12).

FIGURES 16–21. Macrobiotus huziori sp. nov. eggs. (SEM, scale on 17–21 same as on 16).

FIGURES 22–23. Macrobiotus huziori sp. nov. surface of egg processes with the ‘reticulation’.

FIGURES 24–32. Macrobiotus huziori sp. nov. variability of egg processes, shapes and sizes (mid sections). (DIC, scale on 25–32 same as on 24).

FIGURES 33–36. Macrobiotus huziori sp. nov. —variability of egg processes. (SEM).

FIGURES 37–38. Macrobiotus huziori sp. nov.—egg areolation (the same part of egg chorion while focusing down, see also Figs. 43–44). (DIC, scale on 38 same as on 37).

FIGURES 39–42. Macrobiotus huziori sp. nov.—egg areolation. (SEM).

FIGURE 43–44. Macrobiotus huziori sp. nov. semi­schematic drawing explaining the areolation appearance in Light Microscope while focusing down through the egg chorion. Three focusing levels on Fig. 43 () refer to three bird’s­eye views on Fig. 44 (also marked as); p processes, e egg interior. See also Figs. 37–38 and 39–42.

Tables

TABLE 1. Measurements [in µm] and pt values of selected morphological structures of specimens of Macrobiotus huziori sp. nov. mounted in Hoyer’s medium (Range refers to the smallest and the largest structure found among all measured specimens; N, number of specimens/structured measured, SD, standard deviation).

CHARACTER	N		RANGE			MEAN		SD
		µm		pt		µm	pt	µm pt
Body	6	315.0–	455.0	787.5–	913.0	394.2	836.5	59.6	45.4
Buccal tube	6	40.0– 54.0		–		47.0	–	5.7	–
Stylet support insertion point	6	31.5–	42.0	77.8–	80.8	37.1	78.9	4.7	1.1
Buccal tube external width	6	8.0–	12.0	17.3–	22.2	9.3	19.8	1.5	1.6
Macroplacoid 1	6	5.5–	9.0	13.8–	17.4	7.6	16.0	1.5	1.5
Macroplacoid 2	6	4.0–	7.0	10.0–	13.0	5.8	12.2	1.1	1.1
Macroplacoid 3	6	6.0–	12.0	15.0–	22.2	8.9	18.7	2.2	2.5
Macroplacoid row	6	19.0–	31.5	47.5–	58.3	24.8	52.6	4.4	3.6
Claw 1 ­ primary branch	3	10.0–	12.5	25.0–	26.1	11.5	25.5	1.3	0.5
Claw 1 ­ secondary branch	3	8.0–	10.0	20.0–	20.7	9.2	20.4	1.0	0.3
Claw 2 ­ primary branch	5	10.0–	13.0	24.1–	26.1	11.6	25.3	1.3	0.8
Claw 2 ­ secondary branch	5	8.0–	10.0	18.5–	21.3	9.2	20.1	0.9	1.1
Claw 3 ­ primary branch	5	10.0–	13.0	24.1–	28.3	12.0	26.1	1.4	1.6
Claw 3 ­ secondary branch	5	8.0–	10.0	18.5–	21.7	9.2	20.0	1.1	1.2
Claw 4 ­ primary branch	5	13.0–	16.0	28.8–	32.7	15.0	31.1	1.2	1.8
Claw 4 ­ secondary branch	5	9.5–	12.0	21.2–	24.5	10.9	22.6	1.1	1.3