Parotoplana gracilispina sp. n.
Holotype: one karyological slide made permanent with lactophenol (SMNH 7599).
Type locality: Atlit (Israel), beach near the Castle (lat. 32°42’21.01”N, long. 34°56’6.90”E), lower intertidal, medium sand, February 1986.
Additional material: one karyological slide made permanent with lactophenol (CZM 184)
Etymology: the name refers to the slender (latin gracilis) appearance of the copulatory spines.
Description: The sclerotised apparatus consists of 15 spines in the holotype, and 14 in CZM 184:
- Dorsal pairs: D1 : slender, straight, spines ranging 43-44 µm long, with a maximum width at their bases of 1 µm; D2 : stouter spines, 47-51 µm long, about 3 µm wide at their bases, tapering distally.
- Girdle: G1 : two spines, 37-39 µm long, 2-3 µm wide in their middle, tapering towards their bases. With slender, slightly falcate apices and obtuse distal tips. They are provided with small apophyses, located at about 7 µm from the tip; G2 : two straight spines, 46-48 µm long, about 4.5 µm wide in their middle, and tapering basally to 1 µm wide. With very long, slender, straight apices with obtuse distal tips, and with very small apophyses, placed at about 20 µm from the apex; G3 -G4 : ranging in length from 41-44 µm (G3 ) to 48-51 µm (G4 ); stems 2-3 µm wide in their middle. Both pairs have long, falcate apices, with obtuse distal tips and short apophyses placed at about 10-16 µm from the distal tip.
- V: two spines, ranging 44-48 µm in length, and 2.5 µm broad, with very long, slender, falcate apices and blunt distal tip; apophysis flat, 3-3.5 µm long, placed at 17-20 µm from the tip.
No bursal spines were retrieved in the specimens studied.
Karyotype. Chromosome number: n = 6; FN = 10. The first three pairs of chromosomes are distinctly larger than the three remaining pairs. Karyometrical data (based on measurements of nine plates): Chrom. I = r.l.: 25.92 ± 2.13 ; c.i.: 37.13 ± 0.91 (sm); Chrom. II = r.l.: 24.6 ± 1.42; c.i.: 29.03 ± 3.76 (sm); Chrom. III = r.l.: 23.85 ± 2.56; c.i.: 45.24 ± 1.27 (m); Chrom. IV = r.l.: 8.93 ± 1.21; c.i.: 18.07 ± 5.91 (st); Chrom. V = r.l.: 8.84 ± 1.15; c.i.: 28.48 ± 5.81 (sm); Chrom. VI = r.l.: 7.76 ± 2.05; c.i.: 12.18 ± 5.81 (t); haploid genome length: 11.4 ± 0.9 µm.