The World of Protozoa, Rotifera, Nematoda and Oligochaeta
Mytilina
Mytilina Bory de St. Vincent, 1826 (ref. ID; 1345, 3688) or 1836 (ref. ID; 3514, 7815)
Order Ploimida: Family Mytilinidae (ref. ID; 7097)
Synonym Diplacidium Lauterborn, 1913 (ref. ID; 3688), Diplax Gosse, 1851 (ref. ID; 2978, 3688), Salpina Ehrenberg, 1830 (ref. ID; 2978, 3688) reported author and year? (ref. ID; 1923)
ref. ID; 1663
Lorica composed of a ventral plate and two lateral plates, the edges of the latter forming two dorsal ridges. Often with anterior and posterior spines. Foot short. Toes short to long. Littoral species, usually in hard waters. (ref. ID; 1663)
ref. ID; 1837
The various species of soft-skinned Mytilina have many features in common. Koste & Robertson (1913) proposed considering the shape of the toes. (ref. ID; 1837)
ref. ID; 3334
The members of this genus have a well-developed lorica, which is slightly flattened laterally. The dorsal surface has two central ridges separated by a median groove. The anterior and posterior region are, in about half the species, decorated by a number of spines. The foot is short and composed of one or two segments with two long, strong toes. The mastax has malleate trophi. (ref. ID; 3334)
Lorica long, laterally compressed, without spines. Anterior end as wide as posterior end or narrower. Toes long, strong, pointed. (ref. ID; 1806)
The sulcus of the dorsal shell is broad. The carinas have stout, short terminal processes which laterally seem to be pointed. The head indentation is narrow but nearly as long as the total body shell. The toes are bacilliform with ventrally bent tips. (ref. ID; 2834)
Lorica transparent with three keels on the back. Frontal edge smooth and curved. Width of lorica more than half the length. Toes thin and straight ending in an acute point. (ref. ID; 3180)
Measurements
Lorica length 160; lorica high 92; toe & claw 70 µm. (ref. ID; 4606)
It has a soft-skinned shell with a broad dorsal sulcus. There are short spines on the vaulted medioventral head indentation and long dagger-like spines on the dorsal head indentation. The toes are long and broad and protrude from a semitubular extension of the ventral shell. There are paired sensory papillae off the toe base. (ref. ID; 2834)
Measurements
Total length including spines 476; toe length 224; dorsal spines 140; ventral spins 56 µm. (ref. ID; 2834)
Lorica consists of one piece and in cross section the dorsal sulcus is 'V' shaped. There are four spine-like projections at the anterior end which also bears very small spines. (ref. ID; 2715)
Measurements
The length of the anterior and posterior spines varies considerably. (ref. ID; 1450)
Length of lorica 172; width 83; toes 49 µm. (ref. ID; 2715)
While resembling M. mucronata in many respects (it bears a similar pustulated band or collar and the lorica size lies within the recognized limits (Koste 1978), though the toes are about 8 µm longer), the posterodorsal margin of the South Georgia specimens is extended to almost twice the length of the posterior ventro-lateral spines. From a lateral aspect, there is some resemblance to M. mucronata spinigera (Ehrenberg) but when viewed from a dorsal or ventral position, the posterodorsal median projection is seen to be bluntly rounded (like M. mucronata), whereas M. spinigera is produced into a sharp point. (ref. ID; 3334)
Type locality
A number of specimens were found in the Maiviken Lakes, South Georgia, and these would appear to be a hitherto undescribed form of Mytilina mucronata (O.F. Muller). (ref. ID; 3334)
Measurements
It is a medium-sized rotifer with a lorica length of 234-248 µm and toes of 61-68 µm. (ref. ID; 3334)
Posteriorly a single stout mucro on the ventral corner and thovns are lacking on the dorsal margin. Occipitally on the dorsal margin there is ablunt thorn. And only a sharp angle on the ventral margin. Reduced arming differentiate these individuals from the normal type of the species. The very long toes differentiate them from other subspecies.
Type locality
Two individuals at Menggala. (ref. ID; 4604)
Measurements
Total length 205; lorica high 80; posterior thorn 36; toe 180 µm. (ref. ID; 4604)
The species is characterized by the lorica being somewhat triangular in cross section and presenting, at the tip of the lorica, a notch through which the thin median keel is visible. The toes are straight and slightly thickened near the tips. (ref. ID; 2808)
Measurements
Total length 185; toes 70 µm. (ref. ID; 2280)
Lorica length 186; toe length 75-80 µm. (ref. ID; 2808)
Total length 170; length of head section 24; length of body less head 122; length of toes 48 µm. (ref. ID; 3127)
Due to the very often short descriptions and unsatisfactory figures of older authors, until today, there exists a great deal of uncertainty in reference to the soft-skinned Mytilina. This is particularly true for M. crassipes (Lucks, 1912), M. bisulcata (Lucks, 1912), M. unguipes (Lucks, 1912), M. videns (Levander, 1894), and M. compressa (Gosse, 1851). All of them live on mud surfaces. The Marchantaria M. unguipes is the first record for this geographical region. Based on the form of the toes one can separate two groups of these animals: a) Toes long, thin, straight or slightly bent, somewhat pointed at the tip: M. trigona (Gosse, 1851), M. videns (Levander, 1894), M. bisulcata (Lucks, 1912), M. compressa (Gosse, 1851). b) Toes long, thin, straight or slightly bent, ending in soft, flexible claws: M. crassipes (Lucks, 1912) (lorica length 138, toe length 57-75, claw 9 µm), M. unguipes (Lucks, 1912) (lorica length 193, toe length 58, claw 13 µm). (ref. ID; 2808)
Descriptions
This species might be confused with M. bisulcata. The shapes of toes with long, slender ending flexible claws. (ref. ID; 1837)
Anterior margin pustulated. Posterior ventral spines longer than the posterior dorsal spine. (ref. ID; 1929)
M. ventralis can be considered as a fairly variable species. The typical forms have the posterior dorsal and ventral spines of the same length. It was observed that the spine length greatly increased during the end of March resulting in macracantha variety. Length of body, however, was found to be reduced. The macracantha variety exhibited the same length of spines in April even though length of the body decreased. The posterior dorsal spine showed shortening during August and September and the typical forms with short uniform spines appeared in November and March. The brevispina variety occurred in December and February with arched dorsal side and was devoid of posterior spine. (ref. ID; 1939)
Anterior end of lorica heavily stippled. Posterior end narrow. With two well developed toes. (ref. ID; 2704)
The anterior end of lorica with small spines along the edges and hispid to about one-fifth of the length. Posterior end narrow. Dorsal side arched. (ref. ID; 2715)
Lorica stiff, well built with a dorsal sulcus, anterior portion granulated. Two short ventral spines present at the anterior end, posterior spines well developed, ventral longer than dorsal and foot with two toes. (ref. ID; 2867)
Anterior margin pustulated. Posterior ventral spines longer than the posterior dorsal spine. (ref. ID; 3180)
Measurements
Total length 238; posterior dorsal spine 42; posterior ventral spine 56; length of toes 70 µm. (ref. ID; 1929)
Total length 190; length of anterior spines 20 µm. (ref. ID; 2317)
Total length 116; length of anterior spines 4-6; length of posterior spines 18; length of toes 40 µm. (ref. ID; 2385)
Their loricas were about 220 µm long with posterior spines up to 48 µm long, so that they could be allocated to the variety macracantha Gosse. (ref. ID; 2683)
Total length 210; maximum width 95; toes 75 µm. (ref. ID; 2704)
Length of lorica 165; width 81; toe 51 µm. (ref. ID; 2715)
Total length 200; length of lorica 165; maximum width 120; anterior spine 10; posterior ventral spine 20; posterior dorsal spine 20; toes 60 µm. (ref. ID; 2867)
Length of lorica 170-200; width of lorica 70-97; length of anterior spines 25-45 µm. (ref. ID; 3275)
Resembling ventralis var. macracantha, Gosse, but distinguishable from it is lacking the elevation near the frontal lateral margin of the lorica, and the curvature at the base of caudal lower spines, and by having 1) rectangular projection of the ventral side of upper caudal spine, bigger than those of macracantha v. spinigera and 2) dumimg -shaped body. It differed from brevispine in lacking serration of frontal margin and having projection between two caudal spines. (ref. ID; 2587)
Quote from ref. ID; 2587