Entire margin spiny. Lorica heavy, with 4 to 10 long dorsal spines and six posterior spines. Foot short. Mastax malleate. Littoral species. (ref. ID; 1663)
ref. ID; 1923
Remane (1933) proposed to include these species in Trichotria. (ref. ID; 1923)
Although Berzins (1982) states that "Die Art gleicht altamirai, doch unterscheidet sich durch die sehr abweichende Bestachelung", only the relative length of the dorsal spines seems to be different: the median dorsal spines are reported to be very long. No taxonomic weight can, however, be contributed to this character, which is known to be highly variable (Wulfert 1964; Koste 1978). As the number and disposition of the dorsal spines identify the specimens as belonging to M. altamirai, this name is here considered a senior synonym of M. dispar. (ref. ID; 2936)
Contracted lorica almost circular, widest in posterior third, entirely covered (dorsally and ventrally) with small spinulets. Lateral margins of lorica smoothly rounded. Lateral, antero-ventral and antero-dorsal margins with rows of subequal spinulates, those on anterior margins smallest. Posterior margin with a pair of short, curved posterolateral and a pair of stout posteromedian spines. Posteromedian edge convex, bearing two small spinulets. Ventral lorica flat, dorsal lorica with terraced median part, bearing two strong spines in anterior part. Lateral antennae in posterior region, on socle. Head when contracted tube-like with lateral folds, bearing the dorsal antenna and some relative strong spinulets. Foot subterminally, partly covered, consisting of a rigid, elongate distal foot pseudosegment on a variably shaped, retractile basis. Two parallel-sided, equally long toes present. Posterior illoricate part of body ('anal segment') contractile, bearing two pairs of spinulets, the median pair the longest. (ref. ID; 3004)
Male: Male unknown. (ref. ID; 3004)
Comments
The species cannot, by its single pair of dorsal spines, be confused with any congener. The species is strikingly similar to M. danneeli Koste and Shiel, known from Australia (Koste and Shiel 1983) and the South of India (F.K. Kakkassery, pers. comm.): both have two pairs of short posterior spines and a similar round lorica. M. danneeli is reported to have only rudiments of dorsal spines. The postero-lateral and postero-median spines are slightly slenderer and more elongate in M. danneeli than in M. americanus n. sp. (ref. ID; 3004)
Etymology
The specific name americanus is an adjective, referring to the species' area. (ref. ID; 3004)
Type locality
Permanent lagoon of Rio Branco, about 7 km S. of Boa Vista, Roraima, Brazil, 24 June 1987. Conductivity 5.7 uS; O2 7.1 mg/l; temperature (surface) 36.6 degrees C; pH 5.3. (ref. ID; 3004)
Contracted lorica slightly longer thin wide, broadest medially, entirely covered (dorsally and ventrally) with small spinulets. Lateral margins of lorica smoothly rounded. Lateral, antero-ventral and antero-dorsal margins with rows of subequal spinulets, those on anterior margins smallest. Ventral lorica flat, dorsal lorica with terraced median part, with lateral antennae in posterior region, on socle. Head when contracted tube-like with lateral folds, bearing the dorsal antenna and some relatively strong spinulets. Posterior end of lorica with a central, projecting dome and lateral, rounded parts. Subterminal foot partly covered, consisting of a rigid, elongate distal foot pseudosegment on a variably shaped, retractile basis. Two tapering, equally long toe present. Posterior illoricate part of body contractile, covered with minute spinulets. (ref. ID; 3004)
Male: Male unknown. (ref. ID; 3004)
Comments
Although its lorica is entirely covered by minute spinulets, M. aspinus lacks the large dorsal spines, characteristic of the genus. Only M. danneeli equally lacks such dorsal spine, but this species has a different lorica shape and is armed with two pairs of caudal spines as in M. americanus n. sp. The total absence of any large spine is unique to M. aspinus n. sp., which can therefore not be confused with any congener. It is assigned to the genus Macrochaetus by its characteristic lorica shape being covered entirely by minute spinulets, by the shape of its head and foot when contracted, and by its trophi structure. (ref. ID; 3004)
Etymology
The name M. aspinus (adj.) refers to the species' unique characteristic, i.e. the absence of any large spine. (ref. ID; 3004)
Type locality
Permanent lagoon of Rio Branco, about 7 km S. of Boa Vista, Roraima, Brazil, 24 June 1987. Conductivity 5.7 µS; O2 7.1 mg/l; temperature (surface) 36.6 degrees C; pH 5.3. (ref. ID; 3004)
Lorica quadrangular, with a constriction on both sides. Shoulder rounded. The border of the lorica is covered with fine teeth. The dorsal lorica is rough with projections 6 long thorns on the dorsal plate, 4 thorn on the posterior border of lorica, and 2 small thorns on the prolongation of lorica. Double segmented foot, with 2 bristles on the basis of the basal foot segment. Toes cylindrical and terminated in a sharp point on the last third. (ref. ID; 4606)
Type locality
Three individuals from the Karnah River on 13.11.53 and two individuals on 6.03.61 from Riddels Creek (Victoria). (ref. ID; 4606)
M. aspera is pictured as having 4 dorsal, 4 end and 2 anal spines, which corresponds to the diagnosis of M. collinsi. Berzins (1982) reports that "Das innerste Paar von Stacheln am hinteren Panzerrand" is absent, that the form of the lorica is quadrangular, and he comments on the relative length of the dorsal spines. The first characteristic is only relevant when compared to M. altamirai, the two following are known to be variable (Wulfert 1964; Koste 1978). As neither the description not the figure of M. aspera provide any means of separating this taxon from M. collinsi, the former is considered a synonym of the latter. (ref. ID; 2936)
Descriptions
The shape of the lorica is more or less rounded with spines on the margins. There are some large tooth like spines at the antero-lateral margin. The number of these spines varies from specimen to specimen but are usually one to three. The outer anterior dorsal spines are placed higher than the inner spines and their position can be variable according to the state of preservation of the animal. Like the anterior median and lateral spines, the posterior median spines also emerge from fleshy lobes. The lorica is covered with spines. Two forms of M. collinsi were encountered in the sample from Sri Lanka. In one form, there is only one anal segment from the base of which arise the two anal spines. Sometimes two very small spines can also be noticed ventral to this. In the other form the anal segment is composed of three or four segments and the anal spine originates from the third segment with a smaller spine arising from the fourth segment. There are also some spinules at the edges of the anal segment. (ref. ID; 2715)
Lorica more or less rounded with spines on the margins. Large tooth-like spines present at the antero-lateral margin. Posterior median and lateral spines merging from the fleshy lobes. Two anal spines arising from the anal segment. (ref. ID; 3180)
Lorica covered with pustules and granules. Body with usual cross section, egg with elliptical outline. Anal segment spineless. Dorsal lorica with terraced sides to blunt keel. Margin of keel base with longer spinules, terraced rim wider at start, tapering caudally; uppermost keel dorsum covered with large cuticular ledges and beading. Shoulder spines, posterolateral-, posteromedian- and only one pair of rudimentary anterosubmedian spines present. Lateral antennae project from strong three stepped cylindrical pyramid. Ventral lorica with blunt keel and shallow curved, wide foot opening. Foot bi-articulated; toes short, spindle-formed. (ref. ID; 2759)
Discussion
The important taxonomic morphological characteristic of Macrochaetus Perty is the number of spines and longer spinules. Their total number ranges from 8 (without shoulder spines, M. sericus (Thorpe, 1893)) to 16 (M. multispinosus Myers, 1934). Of the possible insertion points of the dorsal spines in the taxon described here. Shoulder hooks and short posteroventral spines are present. The deeply extended spine-free anal segment is, moreover, noteworthy. A Macrochaetus with this morphological characteristic is hitherto unknown. (ref. ID; 2759)
Etymology
This new species is dedicated to Prof. Dr. Ilse Danneel, University of Duisburg. (ref. ID; 2759)
The animal discovered by Riikoja bears a great resemblance to the one which was found by V.G. Thorpe in China in a pond at Wuhu in July 1892 and was described by him under the name of Dinocharis serica. The lorica of the animal however is somewhat more disk-shaped. Both these animals have kerfs on either side of the inner spines at the rectilinear posterior edge of the lorica. Quite striking is also the resemblance between Macrochaetus serica and the animal regarding the shape and especially the size of their toes which are, if compared with those of Macrochaetus collinsii (Gosse) and Macrochaetus subquadratus (Perty) much stronger. There exists also a certain likeness in the teeth at the shoulders of the lorica. In the animal as well as in M. serica a single strong spine-shaped tooth at the shoulders of the lorica is missing; in its place there appears a range of bigger teeth, the number of which, however, in M. serica is always 3 on each side, while their number in the animal varies. In addition to this there are still some other more remarkable differences between M. serica and the animal. The spurs which are absent on the foot of M. serica, are present at the animal, but they are much smaller than those of the two other known species. Further, while M. serica and M. collinsii possess 8 dorsal spines, M. subquadratus - 12, the animal has 10 of them: between the fore and the hind transversal ranges, consisting each of four spines, there is a pair of them rising from the central point of the lorica and standing close together. Above have been given the more important characteristics of this peculiar animal, which differs in several marked features from the three previously described representatives of the genus and to which Riikoja have resolved to give the name of Macrochaetus esthonicus. The most notable of its peculiarities are: the nearly disk-shaped lorica, the small spurs, the rather strong toes and the 10 dorsal spines. (ref. ID; 3378)
Both dorsal bristles (DB) and caudal bristles (CB) 4 in number. Anal bristles (AB) 2 in numbers. Most bristles nearly as long as body length (BL), i.e., 0.9< DB/BL <1.2; 0.8< CB/BL = 0.9; AB/BL = 0.6. (ref. ID; 3083)
Comments
The species resembles both species, longipes Myers, 1934 and hauerianus Wulfert, 1964. It is allied to the former in the possession of relatively long dorsal bristles and longer 2nd foot segment. While, general features remind us, in some degree, of collinsi v. by Hauer (1938: 534, Fig.58), which was named hauerianus by Wulfert (1964: 298, Fig.16), it differs, however, from both in having 1) relatively longer dorsal bristles, 2) nervated bristles and 3) peculiarily angulated bobbin-shaped lorica. Besides, it differs from the latter in the relative length of foot segment, both caudal and anal bristles and rarely provided with foot spines. (ref. ID; 3083)
This species is different from all the other species under Macrochaetus in having illoricate body and extraordinarily longer and strongly nervate bristles and longer foot. (ref. ID; 3083)
Etymology
The name longisetus is derived from the Latin for long seta, alluding to the possession of long seta on the lorica. (ref. ID; 3083)
The absence of anal segment is one of the taxonomical characteristics of M. sericus. In dorsal view, however, both of our taxa have the same number of spines: 4 on the anterior and 4 on the posterior portion of the lorica. Animals with contracted ventral plates are very difficult to identify to species level and many authors have be confused M. sericus with M. collinsi. (ref. ID; 2809)
Descriptions
This species is distinguished by the anal segment is not existent, and by its 8 spines. The lorica have a dense covering of minute tubercules. (ref. ID; 1837)
Body broad. Dorsal surface of the lorica with 8 spines placed symmetrically with respect to middle line. Lorica pustulated. (ref. ID; 1929)
The lorica is horse-shoe shaped with prominent spines at the edges and is wider than long. The two outer antero-dorsal spines are higher than the inner spines, all of which originated from fleshy protuberances. There is no anal segment and the posterior end of the lorica is pushed inward between the posterior outer and inner spines. Though at first glance it resembles M. collinsi it can be distinguished by the aforementioned characters. (ref. ID; 2715)
This species is different from sericus in having 1) a toe fused as in Xenolepadella, 2) short foot and 3) caudal projection from which caudal bristle developed. (ref. ID; 3083)
Etymology
The name is derived from the Latin for union, alluding to the features of fused toes. (ref. ID; 3083)
