Glyphidrilus nanensis 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 : 4

Glyphidrilus nanensis Chanabun & Panha sp. n. Figs 1, 3, 4, Table 1

Type material.

Holotype: One adult (CUMZ 3403) in a rice field near Nan River at Saklek, Phichit, north Thailand (16°30'28.4"N, 100°31'15.0"E), 49 meters elevation on 16 June 2012. Paratypes: 42 adults and 10 juveniles (CUMZ 3404), 2 adults (ZMH 14579), 2 adults (NHMUK), and 2 adults (ZRC), all same collection data as holotype.

Diagnosis.

A small sized earthworm with the clitellar wings on the lateral side of the body in XXIV, XXV, XXVI– XXVII, XXVIII, XXIX. Clitellum in XVII, XVIII–XXXIII, XXXIV. Female pores, male pores, and spermathecal pores not visible. Genital markings: paired or asymmetrical on aa in X, XI, XII, XIII, XIV and XXVIII, XXIX, XXX; paired or asymmetrical on bc in XV, XVI, XVII–XXIII, XXIV, XXV. Four pairs of seminal vesicles in IX–XII. Intestinal origin in XV. Ovaries in XIII–XIV. Spermathecae between 13/14-17/18.

Description of holotype.

Dimensions: body length 78 mm, diameter 2.6 mm in segment VIII, 4.7 mm before the clitellar wing in segment XXIII, 4.2 mm after wing in segment XXX in clitellar region; body cylindrical in anterior part, quadrangular in transverse section behind clitellum. 241 segments. Body color pale brown with variations from red to pink at adjacent tissues of wing portion in different individuals of newly collected specimens. At posterior end dorsal surface considerably broader than the ventral. Clitellar wing on ventro-lateral part of clitellum in XXVI–XXIX, 3.6 mm in height, and 0.3 mm in width on both sides. Prostomium zygolobous. Dorsal pores absent. Clitellum annular in XVII–XXXIII. Four pairs of setae per segment from II, setal formula aa:ab:bc:cd:dd = 1.0:0.6:1.3:0.6:1.4 in segment VIII and 1.0:0.6:1.5:0.6:1.5 in postclitellar segments. Female pores, male pores, and spermathecal pores not visible. Genital markings: paired on aa in XII–XIII, laterally paired or asymmetrical on bc in XVII–XXIV.

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 7/8. Intestine enlarged from XV. Hearts, five pairs in VII–XI, first in VII and last in XI. A pair of holonephridia in each segment from segment XIII onwards. Seminal vesicles, four pairs in IX, X, XI, XII. Ovaries, two pairs in XIII–XIV. Testes free in X and XI. Prostate and accessory glands absent. Spermathecae sessile and diverticula absent, elongated oval or globular between 13/14-17/18, about 0.2-0.3 mm in diameter, two to ten on each side per segment.

Variations.

Body lengths of adult (n = 49) and juvenile paratypes (n = 10). Adults ranged from 72-99 mm (85.2 ± 19.0), with 186-257 segments. Juveniles ranged from 73-93 mm (82.3 ± 7.5), with 186-251 segments. Wings in XXIV, XXV, XXVI–XXVII, XXVIII, XXIX, clitellum in XVII, XVIII -XXXIII, XXXIV. Genital markings: paired or asymmetrical on aa in X, XI, XII, XIII, XIV and XXVIII, XXIX, XXX; paired or asymmetrical on bc in XV, XVI, XVII–XXIII, XXIV, XXV.

Distribution.

The new species was found in the river banks of Nan River at Saklek, Phichit, north Thailand, which was covered with worm casts.

Etymology.

The species was named after the locality on the banks of the Nan River. This was the first time that the worm genus was ever recorded from near this river.

Remarks.

For a summary of the following comparisons please see Table 1. The new species differs from G. yunnanensis Chen & Xu, 1977 reported from China by the latter having longer wings in XXII–XXXII, the clitellum in XVIII–XXXVIII, paired genital markings on bc in XVII–XXI and XXXII–XXXIV, lacking a spermathecae. It differs from G. vangviengensis Chanabun & Panha, 2011 from Laos by G. vangviengensis having longer wings in XXIV, XXV–XXXI, XXXII, the clitellum in XIX, XX–XXXV, XXXVI, XXXVII, and lacking spermathecae. It differs from the species recorded as G. mekongensis Panha & Chanabun, 2012 from the Mekong River, Ubon Ratchathani, northeast Thailand by the latter species having longer wings in XXIV–½ XXXIII, XXXIII, XXXIV, ½ XXXV, the clitellum in XIX–XXXVII, XXXVIII, and lacking spermathecae. It differs from G. borealis Chanabun & Panha, 2013 from Chiangmai, north Thailand by the latter having longer wings in XXI, XXII–XXVII, XXVIII, XXIX, a longer clitellum in XIV, XVI, XVII–XXXI, XXXII, XXXIII, XXXIV, XXXV, XXXVI, and the intestine enlarged from XIII. It differs from G. vangthongensis Chanabun & Panha, 2013 reported from Phitsanulok, north Thailand by G. vangthongensis having longer wings in XXIV, XXV, XXVI–XXXI, XXXII, a longer clitellum in XII, XIII, XIV, XV, XVI–XL, XLI, XLII, an intestine enlarged from XIV, and spermathecae between 12/13-18/19. It differs from G. chaophraya Chanabun & Panha, 2013 from Chaophraya River, Nakhonsawan, central Thailand by the latter having longer wings in XXIV, XXV–XXXII, XXXIII, a longer clitellum in XX–XLIII, XLIV, XLV, and spermathecae between 16/17-22/23. It differs from G. chiensis Chanabun & Panha, 2013 from Mahasarakham, northeast Thailand by G. chiensis having wings in XXIII, XXIV, XXV, XXVI–XXIX, XXX, XXXI, XXXII, the clitellum in XVII, XVIII–XXXIII, XXXIV, XXXV, XXXVI, XXXVII, XXXVIII, and spermathecae between 12/13-18/19. It differs from G. quadratus Chanabun & Panha, 2013 reported from the Mun River drainage area, northeast Thailand by G. quadratus having wings in XXIII, XXIV–XXVIII, XXIX, XXX, XXXI, the clitellum in XV, XVI, XVII, XVIII–XXXI, XXXII, XXXIII, XXXIV, XXXV, XXXVI, and spermathecae between 12/13-17/18. It differs from G. huailuangensis Chanabun & Panha, 2013 recorded from Najahlauy National Park, Ubon Ratchathani, northeast Thailand which has wings in XXV, XXVI–XXX, XXXI, a clitellum in XII, XIII, XVI–XXXII, XXXIII, and lacking spermathecae. It differs from G. sekongensis sp. n. by G. sekongensis sp. n. having longer wings in XXV–XXXI, a longer clitellum in XVI, XVII–XXXVI, XXXVII, and spermathecae between 12/13-15/16 (see Table 1).