Lepidodermella intermedia Kånneby, Todaro & Jondelius, 2012

Kolicka, Małgorzata, 2014, Gastrotricha Mečnikow, 1865 from Copenhagen Palm House - contribution to the knowledge of Lepidodermella intermedia Kånneby, Todaro & Jondelius, 2012 (Chaetonotida, Gastrotricha), Zoosystema 36 (4), pp. 713-722 : 717-721

Lepidodermella intermedia Kånneby, Todaro & Jondelius, 2012

( Figs 1-4 ; Table 1)

LOCALITY. — Copenhagen Palm House.

MATERIAL. — Six specimens (all adult), three photographed. The micro-photographs are available at the Muséum national d’Histoire naturelle in Paris and in the author’s collection.

DESCRIPTION

S mall body-sized species. Body stocky; neck constriction well marked. Head weakly five-lobed semicircular; cephalion, epipleuria and hypopleuria are weakly visible in the body outline. Two pairs of cephalic ciliary tufts on the head – anterior pair (located at U4) shorter cilia than the posterior pair (located at U8). Ocellar granules absent.Mouth ring subterminal and located at U4-U7. Into the mouth a single cuticular tooth situated laterally and visible through the mouth opening. Hypostomium bowl shaped. Neck width narrower than head width. Trunk (from c. U34) slightly and gradually expand to about halfway down the length of the body (c. U59) and subsequently slightly and gradually tapering up to the furcal base (c. U88), relatively thin and short. Furcal branches almost parallell, the adhesive tubes curved slightly inward.

Head, neck and trunk on the dorsal, dorsolateral, lateral, ventrolateral and ventral sides covered with scales, with an extroverted anterior edge giving the impression of a double edge. Scales arranged in 17-21 longitudinal alternating rows, 32-36 scales in each row. Scale edges overlapping. Head scales round to suboval (from c. U2 to c. U17); neck scales almost quadrangular (from c. U18 to c. U33). Dorsal trunk scales quadrangular to pentagonal with more or less rounded edges (from c. U34 to c. U88). Near furcal base at U86, two scales with elliptical anterior edge.Two pairs of dorsal sensory bristles, the anterior ones, on the neck, anchored by papillae at U30 and the posterior ones, at the posterior trunk region, anchored by double-keeled scales at U79-U81. Ventrolateral and ventral body areas covered by scales similar in shape but smaller than those of the dorsal trunk region. Scales of the inner longitudinal alternating rows of scales (from one to three rows) closest to the ventral ciliary bands with weak keels. From the head’s end in the ventral area scales’ keels drawn out into thin, simple spines increasing in length towards the posterior part of the body. The two pairs of the posterior lateral scales located at U86-U87, with simple spines. The posteriormost pair located at U87, with significantly longer and wider parafurcal spines (situated on either side of the furcal base).

Pharynx area of interciliary field (from c. U3 to c. U31) naked. Intestine area (from c. U32 to c. U85) covered with round, smooth scales arranged close and next to one another and with overlapping edges; these situated in alternating rows of six-eight scales. Two pairs of ventral terminal scales at U85- U87, central pair larger. Ventral terminal scales oval, elongated with weak keels and straight spines extending posteriorly beyond the furcal indentation.

Pharynx wide with a well-developed anterior dilatation, and a posterior dilatation is wider than the anterior one. Pharynx connected via the pharyngeal intestinal junction (at U30-U31) to the straight intestine without a separate enzymatic section.

REMARKS

The Lepidodermella intermedia specimens found in the Copenhagen Palm House differ from the original description in the presence of lateral and ventral spines as well as in the distribution of scales on the ventral interciliary field. The recorded specimens had spined scales along the locomotory bands from the head end boundary unlike in the original description, where the scales are described to be present only halfway down the trunk up to the end of the body. Furthermore, the Palm House specimens had two pairs of lateral spiny scales at the furcal base on the sides of the body instead of one, and the scales on the ventral interciliary field covered the entire intestinal section instead of the posterior half of the trunk as reported, in the original description. As Kisielewski (1991) stated in his description of L. minor chaetifer Kisielewski, 1991 the presence/lack of spines and their length may show significant variations even within a single population. Due to a lack of differences in the other taxonomic characteristics, there are no grounds to conclude that the recorded specimens represent a new, separate species. The different morphology of the recorded specimens may be the result of different living conditions (higher water temperature and a more stable habitat) and intraspecies variability (the description of the species was based on a single specimen). However, special attention should be paid to the very strong resemblance between L. intermedia and L. minor chaetifer which likely indicates that they are extremely closely related.

DIFFERENTIAL DIAGNOSIS

Lepidodermella intermedia most closely resembles Lepidodermella minor minor Remane, 1936 and Lepidodermella minor chaetifer Kisielewski, 1991 but differs from:

L. minor minor in terms of: a single denticle in the mouth ring (L. m. minor usually has two cuticular denticles in the mouth ring, albeit the second one can be smaller and less developed vs single cuticular denticles in L. intermedia ), a pair of lateral spined scales and ventral spined scales (no lateral and ventral scales are spined in L. m. minor vs some lateral and ventral scales are spined in L. intermedia ), the shape of the terminal scales on the ventral interciliary field and the degree of coverage of the ventral interciliary field (the ventral interciliary field has only one pair of narrow ventral terminal scales and the remaining area of the ventral interciliary field is scaleless in L. m. minor vs two pair of eliptical ventral terminal scales and all intestine part of ventral interciliary field is covered by scales in L. intermedia ).

L. minor chaetifer in terms of: the number and distribution of scales ( L. minor chaetifer has 15- 31 alternating longitudinal rows of 30-31 scales each vs 17-21 alternating longitudinal rows of 32-36 scales each in L. intermedia ), the shape of terminal scales on the ventral interciliary field ( L. minor chaetifer terminal scales are narrow, has rectangular shape with shallow posterior notches vs to eliptical shape of scales in L. intermedia ), and the degree of coverage of the ventral interciliary field (the ventral interciliary field has only one pair of narrow, rectangular ventral terminal scales with a slightly curved front edge and a shallow posterior notches and the remaining area of the ventral interciliary field is scaleless in L. minor chaetifer vs all intestine part of intercilliary field covered by scales in L. intermedia ).

DISTRIBUTION

Previously recorded only from the locus typicus in Sweden (Mount Njulla, Lapland) ( Kånneby et al. 2012).

Figures

FIG. 1. — Lepidodermella intermedia Kånneby, Todaro & Jondelius, 2012: A, dorsal view; B, view of internal morphology; C, ventral view. Scale bars: 20 µm.

FIG. 2. — Lepidodermella intermedia Kånneby, Todaro & Jondelius, 2012: A, B, C, details of the head: the cuticular denticle in the mouth opening is visible; D, E, ventral views: ventral keeled and spined scales are visible (arrows). Scale bars: 5 µm.

FIG. 3.— Lepidodermella intermedia Kånneby,Todaro & Jondelius, 2012. Dorsal view of scales. Scale bar: 5 µm.

FIG. 4. — Lepidodermella intermedia Kånneby, Todaro & Jondelius, 2012: A, B, detail of the dorsal posterior body region: two pairs of lateral parafurcal spines are visible (arrows). Scale bars: 5 µm.