Glyphidrilus namdonensis Chanabun & Panha

Chanabun, Ratmanee, Inkavilay, Khamla & Panha, Somsak, 2017, New species of semi-aquatic freshwater earthworm genus Glyphidrilus Horst, 1889 from Thailand and Laos (Oligochaeta, Almidae), ZooKeys 672, pp. 1-34 : 12-15

Glyphidrilus namdonensis Chanabun & Panha sp. n. Figs 1, 10, Table 1

Type material.

Holotype: One adult (CUMZ 3424) in the banks of Done River at Ban Namdone, Thakhek, Khammouan, Laos (17°28'39.9"N, 104°45'35.1"E), 161 meters elevation on 6 December 2013. Paratypes: 16 adults and 6 juveniles (CUMZ 3425), 2 adults (ZMH 14583), 2 adults (NHMUK), and 2 adults (RMBR), all same collection data as holotype.

Diagnosis.

Glyphidrilus namdonensis sp. n. is small sized earthworm with distinctly expanded tissues, the clitellar wings on the lateral side of the body in XXIV, XXV–XXVIII, XXX. Clitellum in XIX, XX–XXXVI, XXXVII, XXXVIII. Female pores, male pores and spermathecal pores not visible. Genital markings: medium paired or asymmetrical on aa in XIII, XIV; paired or asymmetrical on bc in XXII, XXIII, XXIV and XXVII, XXVIII–XXXIII. Four pairs of seminal vesicles in IX–XII. Intestinal origin in XVI. Ovaries in XIII–XIV. Spermathecae between 14/15-18/19.

Description of holotype.

Dimensions: body length 92 mm, diameter 3.5 mm in segment VIII, 4.0 mm before the clitellar wing in segment XXIII, 4.0 mm after the wing in segment XXXI in the clitellar region; body cylindrical in the anterior part, quadrangular in transverse section behind clitellum. 216 segments. Body color pale brown with variations from red to pink in adjacent tissues of the wing portions in different individuals of newly collected specimens. Clitellar wing on ventro-lateral part of clitellum in XXIV–XXX, 5.0 mm in height, and 0.2 mm in width on both sides. Prostomium zygolobous. Dorsal pores absent. Clitellum annular in XX–XXXVII. Four pairs of setae per segment from II, setal formula aa:ab:bc:cd:dd = 1.3:0.5:1.0:0.5:2.0 in segment VIII and 1.5:0.5:1.0:0.5:2.3 in postclitellar segments. Female pores, male pores, and spermathecal pores not visible. Genital markings: medium paired on aa in XIII, XIV, laterally paired or asymmetrical on bc in XXII, XXIII.

Septa 5/6-8/9 thicker than between other segments, 9/10-14/15 thick, and 15/16 to the last segment thin. Gizzard small, globular in VIII. Intestine enlarged from XVI. Hearts, five pairs in VII–XI, first in VII and last in XI. A pair of holonephridia in each segment from segment XII onwards. Seminal vesicles, four pairs in IX, X, XI, XII. Ovaries two pairs in XIII and XIV. Testis free in X and XI. Prostate and accessory glands absent. Spermathecae sessile and diverticula absent, small elongated oval or globular between 14/15-18/19, about 0.1-0.2 mm in diameter, two to thirteen on each side per segment.

Variations.

Body lengths of adult (n = 23) and juvenile paratypes (n = 6). Adults ranged from 90-139 mm (121.9 ± 25.9), with 183-259 segments. Juveniles ranged from 87-136 mm (103.3 ± 17.4), with 185-223 segments. Wings in XXIV, XXV–XXVIII, XXX, clitellum in XIX, XX–XXXVI, XXXVII, XXXVIII. Genital markings: medium paired or asymmetrical on aa in XIII, XIV; paired or asymmetrical on bc in XXII, XXIII, XXIV and XXVII, XXVIII–XXXIII.

Distribution.

The new species was found only from the banks of Done River at Ban Namdone, Thakhek, Khammouan, Laos.

Etymology.

The species was named after the Done River.

Remarks.

Glyphidrilus namdonensis sp. n. is compared with other Glyphidrilus having spermathecae and a clitellum starting feom segment XIX. Glyphidrilus namdonensis differs from G. champasakensis sp. n. by the latter having longer wings in XXIII, XXIV–½ XXXII, XXXII, XXXIII, longer clitellum in XIX, XX–XLIX, L, LI, LII, and spermathecae between 14/15-19/20 (see Table 1).