Pseudechiniscus juanitae De Barros, 1939

Pilato, Giovanni & Lisi, Oscar, 2006, Notes on some tardigrades from southern Mexico with description of three new species, Zootaxa 1236, pp. 53-68 : 54-60

Pseudechiniscus juanitae De Barros, 1939

( Fig. 1 A–C)

Material examined

Three specimens in an undetermined moss sample developing on rock.

Description

The description of P. juanitae (locus typicus: Brazil, Estado de S. Paulo) is very brief and it is difficult to make a positive identification of the species. Unfortunately the type material of this species is lost and therefore we must attempt to resolve the problem (in a hypothetical way) through some observations and reasoning.

The length of internal and external buccal cirri and of filament A are not indicated; the presence or absence of a spine on the first pair of legs and the presence or absence of a papilla on the hind legs are not specified. The length of claws is indicated but the pair of legs is not specified and whether internal or external claws had been measured. Details are provided about the dorsal cuticular sculpture, and it is specified that the pseudosegmental plate lacks marginal spines, that the dentate fringe on the hind legs is absent, and that the claws lack spurs.

Remarks

De Barros also recorded the species in a second paper (1942a), but she referred to the same locality and did not add details to the description. Probably she referred to the typical material.

Schuster & Grigarick (1966) recorded P. juanitae from the Galápagos Islands but they wrote that the pseudosegmental plate “showed variation from a simple margin to a narrow transverse flap, to 2 small triangular teeth, to 2 large rounded or acute processes”. They drew (p. 320, Fig. 4 D) claws with a spur.

We have doubts about the specific diagnosis of Schuster & Grigarick (1966) because in the papers of De Barros (1939, 1942a) we did not find any trace of the presence of marginal lobes or teeth in the pseudosegmental plate, and by comparing P. juanitae with P. novaezeelandiae f. marinae, De Barros (1939, 1942a) wrote: “ P. novezeelandiae , forma marinae Bartos, 1934 distingue­se da espécie atual pelos dois dentes mamilares no bordo posterior da placa pseudosegmentária”.

Ramazzotti (1962), Rammazzotti & Maucci (1983) and Maucci (1986) recorded P. juanitae from Austria and Italy, but we have doubts about these specific diagnoses. In fact, Maucci (1986) specified that the cuticular dots are spaced, particularly on the terminal plate where the distance from one dot to another may be more than double their diameter. De Barros (1939, 1942a) did not mention this characteristic. We examined specimens from Austria of Maucci’s collection and we can confirm that the cuticular dots are clearly spaced. In our specimens from Mexico the cuticular dots are not so spaced ( Fig. 1 A). Moreover, De Barros (1939, 1942a) specified that the dots on the cephalic plate and on the scapular plate are smaller and more numerous than on the other plates; this characteristic is evident in our specimens from South Mexico ( Fig. 1 A) while it is not so evident in the specimens from Austria.

Ramazzotti (1962) and Ramazzotti & Maucci (1983) wrote that the claws of the specimens from Austria do not have spurs; conversely, Maucci (1986) wrote that a small spur is present. We confirmed that a spur is present on the internal claws of the specimens of the collection of Maucci that we examined. The problem of the presence or absence of a spur on the internal claws of P. juanitae is difficult to solve. We can hypothesize that P. juanitae lacks spurs or that De Barros was not able to see them. We think the second hypothesis is more probable because our three specimens from southern Mexico seem to coincide with the description of P. juanitae and the spurs on the internal claws are present but may be very difficult to see ( Fig. 1 B, C).

De Barros (1939, 1942a) did not describe the cuticular ornamentation of the ventral surface; the specimens from south Mexico have a group of larger dots in the head region and between the legs while in other parts of the ventral surface the dots are smaller and form a reticular design. The specimens from Austria instead of the reticular design have an uniform ornamentation.

In conclusion the characters of the specimens we examined induce us to attribute the specimens from south Mexico to P. juanitae and to consider the specimens from Austria and Italy as belonging to a different, today undetermined, species.

In Table 1 the dimensions of some structures of our specimens from south Mexico are indicated.

As a consequence of these statements, we think that P. juanitae is present in South America and, as here stated, in Central America, and that the other records are uncertain and need to be confirmed.

Material examined

Holotype (slide N. 4980) and 18 paratypes from an undetermined moss sample developing on a tree; two paratypes from an undetermined moss sample developing on rock.

Species diagnosis

Cuticular plates with very marked margins; posterior margin of the scapular plate with a median concavity; a median dimple is present between the scapular plate and the median plate 1; pseudosegmental plate with a triangular lobe raised dorsally; terminal plate not faceted; all plates with dots joined to one another by very fine striae; filament A present; no other lateral or dorsal appendage present; leg I without spine; hind legs without dentate fringe; claws without spurs.

Description of the holotype

Body length 184 m, colour reddish; eye spots black. Cuticular plates with very marked margins; neck plate not distinct from the head plate that has a slightly evident Wshaped fold and a transversal band with less evident sculpture. The posterior margin of the scapular plate is raised and, due to the presence of a median concavity, a very evident median dimple is present between the scapular plate and the median plate 1 ( Fig. 2 A,B). This plate has a transversal fold. Median plates 2 and 3 undivided. The paired plates II and III have a transverse groove. The pseudosegmental plate has a very evident triangular lobe raised dorsally ( Fig. 2 A,B,E). Terminal plate not faceted, with two incisions. Two small supplementary plates are present laterally to the median plates 1 and 2.

m.

Pseudechiniscus gullii sp. n.

Smallest specimen Largest specimen

Body length 157 184

Internal buccal cirri 9.2 10.0

External buccal cirri 13.2 15.7

Cephalic papilla 3.3 3.6

Clava 3.6 4.3

Cirrus A 24.7 32.7

Papilla of hind legs 2.2 2.9

External claws II 7.6 8.6

External claws II 7.4 8.9 All plates with circular dots; head plate with a dense sculpture with small dots ( Fig. 2 A,B). In all other plates the dots are joined to one another by very fine striae; as a consequence, each dot is in centre of a polygon (generally a hexagon) ( Fig. 2 A,B,E). Scapular plates, paired plates II and III, pseudosegmental plate and terminal plate have larger dots in the median portion (diameter up to 1.3 m); the supplementary plates have smaller dots (slightly larger in the anterior portion, very small in the posterior portion) ( Fig. 2 C,E). A band with the same kind of sculpture (finer and with almost invisible striae) is present on the legs ( Fig. 2 C,E). Ventral body surface with a band of fine dots between the legs; very fine dots are also present in the posterior portion, near the gonopore.

External and internal buccal cirri 15.7 m and 10 m long respectively; cephalic papilla 3.6 m long, filament A 32.7 m and clava 4.3 m long ( Fig. 2 C). No other lateral or dorsal appendage is present. Leg I without spine; hind legs without dentate fringe but with a papilla 2.9 m long. Claws without spurs ( Fig. 2 D). External and internal claws of the second pair of legs 8.6 m and 8.9 m long respectively.

The paratypes are similar to the holotype both in qualitative and metric characters. In Table 2 the dimensions of some structures of the smallest and the largest measured specimens are indicated.

Etymology

The name gullii is in honour of the entomologists Giacomo and Gino Gulli (Catania).

In particular it differs from P. quadrilobatus by having a dimple between the scapular plate and the median plate 1 (in P. quadrilobatus the caudal margin of the scapular plate has a median lobe); in having denser cuticular dots joined to one another by less evident striae; shorter and stouter claws.

The new species differs from P. bartkei unilobatus by having the margins of the cuticular plates raised; caudal margin of the scapular plate very raised and with a concavity forming a dimple between the scapular plate and the median plate 1; less evident striae joining the cuticular dots; claws without spurs.

The new species differs from P. jubatus in having the raised caudal margin of the scapular plate with a concavity forming a dimple between the scapular plate and the median plate 1 (in P. jubatus the caudal margin of the scapular plate has a median rounded lobe); cuticular dots joined to one another by striae; filaments A not biforked at their extremities; claws without spurs.

P. gullii sp. n. differs from P. alberti in having the raised caudal margin of the scapular plate with a concavity forming a dimple between the scapular plate and the median plate 1 (in P. alberti the caudal margin of the scapular plate has a median lobe); median plates, paired plates II and III and pseudosegmental plates without lobe and spines; spine E absent; cuticular dots joined to one another by striae; external cirri and filaments A not biforked; first pair of legs without spine; hind legs without dorsal spines; internal claws without spurs.

P. gullii sp. n. differs from P. occultus in the following features: the raised caudal margin of the scapular plate has a concavity forming a dimple between the scapular plate and the median plate 1 (in P. occultus the caudal margin of the scapular plate has two triangular lobes); lateral spines B, C, D and E absent; pseudosegmental plate with only one triangular median lobe; claws without spurs.

The new species differs from P. ramazzottii in the following features: the raised caudal margin of the scapular plate has a concavity forming a dimple between the scapular plate and the median plate 1; lobe of pseudosegmental plate triangular in shape, never bilobate; cuticular dots larger and joined to one another by very fine striae absent in P. ramazzottii ; papilla on legs IV shorter.

Figures

FIGURE 1. Pseudechiniscus juanitae. A. habitus. B. Anterior portion of the body; the cephalic appendages are focused. C. Anterior portion of the body; a spur is visible on the internal claws of the first pair of claws. Scale bar = 10 m.

FIGURE 2. Pseudechiniscus gullii sp. n. A. Holotype on dorsal view; the dimple between the scapular plate and the median plate 1 is evident. B. Paratype on dorsal view. C. Anterior portion of the body of a paratype; the cephalic appendages are focused. D. Claws of the second and third pairs of legs (holotype). E. Posterior portion of the body of a paratype on lateral view. Scale bar = 10

FIGURE 4. Minibiotus continuus sp. n. A. Habitus and bucco­pharyngeal apparatus of the holotype (scale bar = 20 m). B. Claws of the third pair of legs of a paratype. C. Claws of the fourth pair of legs of a paratype. D. egg. E – F. Detail of the eggs where the hyaline layer is evident. Scale bar = 10 m.

Tables

TABLE 1. Dimensions (in m) of some structures of the smallest and the largest specimens of Pseudechiniscus juanitae from Mexico.

	Pseudechiniscus	juanitae
	Smallest specimen	Largest specimen
Body length	170	175
Internal buccal cirri	9.6	9.6
External buccal cirri	14.5	14.5
Cephalic papilla	4.4	4.4
Clava	4.6	4.0
Filament A	27.4	26.0
Papilla of hind legs	?	3.7
External claws III	6.4	6.8
Internal claws III	6.9	7.3
External claws IV	7.3	7.3
Internal claws IV	7.8	7.9
Pseudechiniscus gullii sp. n. (Fig. 2A–E)
Locus typicus Southern Mexico, Chiapas,	Selva El Ocote.