Nais badia, Peng, Yu, Wang, Hongzhu & Cui, Yongde, 2014

Peng, Yu, Wang, Hongzhu & Cui, Yongde, 2014, Two species of Naididae (Annelida, Clitellata) from southern Tibet, China, ZooKeys 444, pp. 59-68 : 60

Taxon classification Animalia Haplotaxida Naididae

Nais badia sp. n. Figs 1, 2, 3; Table 1

Holotype.

IHB XZ20130630a, whole-mounted specimen, immature.

Type locality.

Wetland in Cuomujiri Mountain (29°47'46"N, 94°24'53"E), southern Tibet of China. 30 June 2013, collected by H.Z. Wang, Y.D. Cui, Y.J. He and Y. Peng.

Paratypes.

IHB XZ20130630b-f, 2 whole-mounted specimens (mature), 2 whole-mounted specimens (immature), 1 specimen is used for scanning electron microscopy. 30 June 2013, collected from the type locality.

Other material.

40 specimens are preserved in 10% formalin. 30 June 2013, collected from the type locality.

Etymology.

The specific name “badia” is Latin for “badius”, and refers to this worm’s large area of reddish brown pigment in anterior segments I-VIII.

Description.

Length 4.2-9.1 mm (Holotype 7.2 mm), width at V 0.3-0.6 mm (Holotype 0.6 mm). Segments 24-54 (Holotype 52). Prostomium conical, eyes present, large area of reddish brown pigment in segments I-VIII (Fig. 1 A–B). Clitellum inconspicuous. Coelomocytes present. Stomach dilatation sudden in VII–VIII. Wave-like movements.

Dorsal chaetae beginning in VI onwards (Fig. 2A). Hairs (0)1-3 per bundle, 137-325 µm long, all serrate (Fig. 2 B–C). Needles (0)2-3 per bundle, 80-90 µm long, distal tooth slightly longer than the proximal one (VII 3.8 µm /3.2 µm), completely pectinate with 1-2 intermediate teeth (Fig. 2D), nodulus often inconspicuous, 1/3 from the distal end (Fig. 3C). Ventral chaetae in II-V 7-8 per bundle, the rest 2-6(7) per bundle, 105-128 µm long, distal tooth longer and thinner than the proximal one (7.5 µm /5 µm), about 50% of ventral chaetae with 1-2 fine intermediate teeth (Fig. 2 E–F), nodulus median or slightly distal (Fig. 3 A–B). Penial chaetae 4 on each side in VI, with a simple hook, 115-155 µm long, 4.2-6.3 µm thick (Fig. 3D).

Pharyngeal glands in II–III. Clitellum in V–VI. Male genitalia paired in V–VI (Fig. 3E). Vasa deferentias 260-273 μm long, with prostate gland cells covering only on their posterior part, join atria subapically (Fig. 3E, vd and pr). Atrial ampullae large and ovoid, 150-160 μm long, 70-90 μm wide, ducts short and narrow (Fig. 3E, at). Spermathecal ampullae globular, length 80-100 µm, width 75-90 µm, spermathecal ducts long and narrow, length 60-70 µm, width 15-16 µm (Fig. 3E, sp).

Distribution.

Known only from Cuomujiri Mountain, southern Tibet of China. High mountain, wetland, hydrophytes abundant (Fig. 1C).

Remarks.

The presence of eyes, dorsal chaetae beginning in VI consisting of hairs and double-pronged needles, pharynx in II-III, stomach beginning in VII, coelomocytes present, spermathecae with distinct ducts, male ducts paired in V–VI, vas deferens with prostate glands joining atrium subapically, atrium without prostate, penial chaetae present with a simple hook, indicate that this new species fits the definition of Nais Müller, 1773 ( Sperber 1948; Brinkhurst and Jamieson 1971).

Nais badia sp. n. is distinguished from congeners for having a large area of reddish brown pigment in anterior segments I-VIII, hairs all serrate, needles pectinate with 1-2 intermediate teeth, ventral chaetae with (0)1-2 fine intermediate teeth (Only visible under SEM) and wave-like movements (Table 1). We are hence of the opinion that it can be described as new to science.

This new species is similar to Nais africana Brinkhurst, 1966 for having pectinate needles, but differs from it by its ventral chaetae in II-V differing from the rest, although the position of Nais africana in the genus is regarded as uncertain due to a lack of detailed examination of live worms and sectioned materials ( Brinkhurst 1966). Nais elinguis resembles the new species on the needles and simple pointed penial chaetae, but its long and wide atrial duct, slow stomach dilatations and the vas deferens which is completely surrounded by abundant prostate gland cells are significantly different from the new species. With regard to the vas deferens completely surrounded by prostate gland cells on their posterior part, this new species is similar to Nais communis , Nais variabilis and Nais pardalis . However, some characteristic features of these species distinguish them from the new species. Nais communis eyes are generally absent, stomach dilatations are slow and the atrium is as long as the duct. Nais variabilis , Nais pardalis and Nais bretscheri all have the ventral chaetae in II-V that differ from the remaining segments. Nais pardalis the stomach has obvious elongated cells. Nais bretscheri the ventral chaetae have typical giant chaetae.