The World of Protozoa, Rotifera, Nematoda and Oligochaeta
Platyias
Platyias Harring, 1913 (ref. ID; 1345) (= Platyas) (ref. ID; 3688)
Class Rotatoria: Order Ploimida: Family Brachionidae (ref. ID; 7097)
Synonym Noteus Ehrenberg, 1832 (ref. ID; 1345, 3688)
Most confused Brachionus patulus-group
ref. ID; 1663
Dorsal and ventral plates of lorica completely fused laterally. Anterior dorsal margin of lorica usually with four or six spine. Body moderately flattened dorso-ventrally. Foot segmented and retractile. Two toes. Mastax malleate. (ref. ID; 1663)
ref. ID; 1923
Foot jointed, not retractible within body. (ref. ID; 1923)
ref. ID; 2715
Wulfert (1965) revised this genus and has removed all the species except P. quadricornis from stand has included in the genus Brachionus. Identification of species based on Ahlstrom (1940) and Wulfert (1965). This genus is represented by only one species. (ref. ID; 2715)
Platyias bicornis Zivkovic, 1974 (ref. ID; 3135 original paper)
Platyias felicitas Wulfert, 1956 (ref. ID; 2136, 2932 original paper)
Lorica oval, dorsoventrally flattened and anterior end broader than posterior. Anterior spines 2, long, curved outwards, acutely pointed with closely placed bases. Posterior spines long, pointed with widely separated bases. Dorsal plate of lorica without polygonal markings. In some specimens, entire lorica stippled. (ref. ID; 1806)
Platyias leloupi var. aspina De Ridder, 1991 (ref. ID; 2935 original paper)
Descriptions
A small morph (total length 230 to 250 µm), without ornamentation on the dorsal plate, and without posterolateral spines. Length of anterior median spines 80 µm. (ref. ID; 2935)
Type locality
Encountered in plankton of Oued Tabaraket, taken on 09.06.1978. The water was slightly oligohaline. (ref. ID; 2935)
Until the contrary is proved, we consider Platyias patulus ((var.)) macracanthus as a distinct species, because there are no intermediate forms known between it and Platyias patulus; moreover, following Ahlstrom (1940), both may be met with in the same sample. Our opinion is that the discussed forms are sibling-species, to be united in a ultra-species: Platyias U. patulus. Platyias [patulus] macracanthus differs from Platyias [patulus] patulus in having the posterior spines much longer, and the lateral palpi of the posterior spines placed directly on the latter; further, the left median posterior spine is the longest in Platyias [patulus] macracanthus, whereas it is the shortest in Platyias [patulus] patulus. (ref. ID; 2328)
Measurements
Length 210-224; maximum width 140-140 µm. (ref. ID; 1929)
Length of body over spines 135; length of spines (from left to right in dorsal view) occipital 20-18-40; pectoral spines 20-14; posterior spines 10-18-14-10 µm. (ref. ID; 2385)
Dorsal lorica length (without spines) 95-130; width at the basis occipital lateral spines 70-140; widest part 52-89; anterior median sinus 20-50 wide, 30-50 deep (dorsal), 38 long, 29 deep (ventral); anterior lateral spines 20-40 (dorsal), 50 (ventral); anterior intermedians 28-38 (dorsal), 38 (ventral); thelytokous egg 72x80 µm. (ref. ID; 3083)
Two occipital spines and the mental margin is without spines. Lorica with regular pattern of facettes. (ref. ID; 1929)
The tips of anterior median spines are invariably curved ventrally. (ref. ID; 2715)
Lorica tuberculate, with three central polygons. Anterior margin of lorica with raised edge, having two median spines, bluntly rounded to truncate at tips. Two posterior spines, short and widely separated with each other. (ref. ID; 2867)
Anterior dorsal margin with two stout median spines that taper but little and are bluntly rounded to nearly truncate at their tips. Mental margin depressed toward the center and serrate. Lorica terminating posteriorly in two rather short and stout, parallel spines, a third to a half the width of the lorica apart. Lorica tuberculate. (ref. ID; 3180)
Measurements
Total length 305; maximum width 178 µm. (ref. ID; 1805)
Total length 266-280; length of lorica 168-182; maximum width 196-220; anterior spines 42-56; posterior spines 28-42 µm. (ref. ID; 1929)
Length of body over spines 360; width of body 220; length of anterior spines 70; length of posterior spines 60 µm. (ref. ID; 2385)
Total length 290; maximum width 160; anterior spines 45; posterior spines 36 µm. (ref. ID; 2704)
Total length 319; width 156; anterior spine 42; posterior spine 24 µm. (ref. ID; 2715)
Total length 240; length of lorica 160; maximum width 160; length of anterior spine 50; length of posterior spine 30 µm. (ref. ID; 2867)
It differ from P. quadricornis in the presence of cuticular plates at the base of first foot-joint. (ref. ID; 1803)
Descriptions
Lorica pear-shaped, firm and compressed antero-dorsal margin provided with two stout spines bending ventrally and tapering into acute points; posterior spines longer than the anterior, with swollen bases and tapering into claw-like acute points. Lorica tuberculated with regular facets. Foot jointed and nonretractile; proximal region of the first joint girdled by characteristic cuticular plates; toes long, spindle-shaped and ending in points. (ref. ID; 1803)
This species with descriptions of P. quadricornis in having tuberculated lorica with regular facets, jointed and nonretractile foot and antero-ventral margin without spines, but differs in having a large pear-shaped body, anterior spines ending in acute points, longer posterior spines with swollen bases and claw-like points, and in having base of first foot joint girdles by characteristic cuticular plates. Ahlstrom states that the lengths of toes and of anterior and posterior spines of P. quadricornis are variable. He recorded a small variant along with a large form having a width of 225 µm and with posterior spines measuring 80 µm, without any evidence of intergradation, based on collections from Florida. Interestingly, the present large specimen occurred without any evidence of intergradation, exhibiting new characters apart from the difference in maximum length. The claw-like acute points of the posterior spines, and cuticular plates at the base of the first foot-joint are distinctive characters. Hence the large variant is considered a new subspecies: Platyias quadricornis andhraensis. (ref. ID; 1935)
Measurements
Total length 280-308; maximum width 238-252; length of anterior spines 70; length of posterior spines 98; length of toes 56; width at anterior end of lorica 140; distance between posterior spines 98 µm. (ref. ID; 1935)