Heterolepidoderma

Garraffoni, André R. S. & Melchior, Marina P., 2015, New species and new records of freshwater Heterolepidoderma (Gastrotricha: Chaetonotidae) from Brazil with an identification key to the genus, Zootaxa 4057 (4), pp. 551-568 : 565-566

Key to Freshwater Species of the Genus Heterolepidoderma

1. Body elongated (130–190 µm)........................................................................... 2

- Body short, compact (90–120 µm)........................................................................ 9

2. Posterior trunk region drastically reducing in width, head shaped as an isosceles trapezoid.... H. trapezoidum Kånneby, 2011

- Posterior trunk region tapering gently in width, head shape rounded, not as an isosceles trapezoid...................... 3

3. Head three-lobed...................................................................................... 4

- Head five-lobed....................................................................................... 6

4. Internal edges of furca base with one pair of short spines; adhesive tubes very short, fairly thick, and slightly bifurcate............................................................................. H. brevitubulatum Kisielewski, 1981

- Internal edges of furca base without one pair of short spines; adhesive tubes elongated............................... 5

5. Presence of a transverse band of cilia on the head connecting the two bands of longitudinal ventral cilia; some longitudinal rows of dorsal scales with diagonally arranged scales in the neck and rearmost trunk regions............ H. mariae sp. nov.

- Absence of transverse band of cilia on the head connecting the two bands of longitudinal ventral cilia; longitudinal rows of dorsal scales parallel to the body axis.................................................... H. majus Remane, 1927

6. Scales and keels hardly noticeable..................................................... H. gracile Remane, 1927

- Strongly keeled scales..................................................................................7

7. Furca base without scales; adhesive tubes forcipate............................... H. longicaudatum Kisielewski, 1979

- Furca base covered with scales; adhesive tubes more or less straight pointing slightly outward at their distal ends..........8

8. Oval scales in 35–40 longitudinal rows; Ventral ciliation as a two separate longitudinal bands for the whole body................................................................................. H. kossinense Preobrajenskaja, 1926

- Elliptical scales in 30–32 longitudinal rows; Ventral ciliation as a continuous field of transverse rows covering the entire ven- tral body surface in the pharyngeal and beginning of the intestinal regions, splitting at the beginning of the intestinal region to form two separate longitudinal bands........................................ H. famaillense Grosso & Drahg, 1991

9. Presence of cuticular reinforcements (or rods) in the anterior part of the pharynx................................... 10

- Absence of cuticular reinforcements (or rods) in the anterior part of the pharynx...................................13

10. Two pairs of cuticular reinforcements (or rods) in pharynx.......................... .. H. dimentmani Kisielewski, 1999

- One pair of cuticular reinforcements (or rods) in pharynx..................................................... 11

11. Paired ventrolateral row of delicate lamellae absent................................. H. joermungandri Kånneby, 2011

- Paired ventrolateral row of delicate lamellae present......................................................... 12

12. Interciliary area in pharyngeal and anterior part of intestinal portions naked, 35 longitudinal rows of scales........................................................................................... H. jureiense Kisielewski, 1991

- Entire interciliary area covered with small keeled scales with spiny processes, 17–23 longitudinal rows of scales................................................................................ H. lamellatum Balsamo & Fregni, 1995

13. Longitudinal rows of dorsal scales more or less curved....................................................... 14

- Longitudinal rows of dorsal scales straight, parallel to the longitudinal axis...................................... 17

14. Pharynx swellings only at the posterior end (large terminal bulb); 40–45 longitudinal rows of dorsal scales.......................................................................................... H. multiseriatum Balsamo, 1978

- Pharynx cylindrical or with swellings at both ends; 10–25 longitudinal rows of dorsal scales..........................15

15. Pharynx cylindrical................................................................ H. patella Schwank, 1990

- Pharynx with swellings at both ends...................................................................... 16

16. Crescent-shaped scales present; ocellar granules absent..................................... H. obliquum Saito, 1937

- Crescent-shaped scales absent; ocellar granules present................................. H. macrops Kisielewski, 1981

17. Presence of keeled scales with a band of simple spines on dorsal trunk............... H. acidophilum Kånneby et al. 2012

- Absence of keeled scales with a band of simple spines on dorsal trunk........................................... 18

18. Scales unkeeled (minute spine-like point distally), oblong to triangular; presence of a pair of round scales on the ventral side of the furca base.......................................................... H. pineisquamatum Balsamo, 1980

- Scales keeled; absence of a pair of round scales on the ventral side of the furca base................................ 19

19. Scales visible; oblong-elliptical keeled scales, which taper distally to short simple spine (8–9 µm)................................................................................................. H. ocellatum Metschnikoff, 1865

- Scales minute; keels very delicate and hardly visible (1–2.5 µm)............................................... 20

20. Pharynx swelling only at the posterior end (large terminal bulb); extremely wide trunk........... H. obesum d'Hondt, 1967

- Pharynx swellings at both ends; neck constriction gradually widens into the trunk.................................. 21

21. One pair of ocellar granules; furca base without scales........................... H. tenuisquamatum Kisielewski, 1981

- No ocellar granules; furca base covered with scales.................................... H. illinoisense Robbins, 1965