Polypheretima insularis Nguyen & Nguyen, 2017

Nguyen, Tung T., Trinh, Kim-Binh T., Nguyen, Hong-Lan T. & Nguyen, Anh D., 2017, Earthworms (Annelida: Oligochaeta) from islands of Kien Hai District, Kien Giang Province, Vietnam, with descriptions of two new species and one subspecies, Journal of Natural History 51 (15 - 16), pp. 883-915 : 904-908

Polypheretima insularis Nguyen & Nguyen sp. nov.

( Figure 15 )

www.zoobank.org/ urn:Isid:zoobank.org:act:C3791A70-BE28-4AD6-9401-4A7B9C961922

Material examined

Holotype. 1 mature (CTU-EW 099.h01), Hon Tre Island (09°58 ʹ 11 ʹʹ N, 104°50 ʹ 9.4 ʹʹ E), Kien Hai Distrist , Kien Giang Province, 13 November 2013, coll. Kim-Binh T. Trinh.

Paratypes. 14 matures (CTU-EW 099.p02) sampled together with holotype; 5 matures (CTU-EW 099.p03), same data as holotype, but collected 10 October 2014 .

Diagnosis

Body cylindrical, medium-large size, length 95–191 mm, diameter 5.4–7.8 mm, 88–182 segments. Prostomium 1/3 epilobous. First dorsal pore in 11/12 or 12/13. Setal number 30–39 in viii, 50–68 in xxx, 5–13 between male porophores in xviii; setal distance aa = 1.1–2.0 ab, zz = 1.2–2.0 zy. Spermathecal pores multiple in dorsolateral intersegments 4/5/6/7. Male pores located inside copulatory pouches in xviii. No genital markings in the spermathecal region, but a pair of slightly elevated, oval-shaped genital markings in front of setal rings of xix, in line with male pores. Testis sacs separated. Holandric. Intestinal caeca absent. Septa 8/9/10 absent.

Etymology

‘ insularis ’ adjective in apposition to refer to islands where the type was found.

Description

External characters. Body cylindrical, medium-large size; length 95–191 mm, diameter 5.4–7.8 mm, segments 88–182, weight 1.55–6.25 g. Body uniformly light grey except clitellum greyish brown. Setae perichaetine; pre-clitellar setae sparser than post-clitellar setae, 30–39 in viii, 50–68 in xxx, 5–13 between male porophores in xviii; setal distance aa = 1.1–2.0 ab, zz = 1.2–2.0 zy. Prostomium 1/3 epilobous (open). First dorsal pore in 11/12 or 12/13 (5 specimens). Clitellum annular, xiv–xvi, smooth and rarely with setae and dorsal pores. Female pore single, mid-ventral in xiv.

Multiple spermathecal pores distinctly visible, in dorsolateral intersegments 4/5/6/7. No genital markings in spermathecal region.

Male pores round, deeply located inside copulatory pouches in xviii; ventral distance between male porophores about 0.35× body circumference. A pair of slightly elevated, oval-shaped genital markings in front of setal rings of xix, in line with male pores.

Internal characters. Septa 5/6/7/8 thickened, 8/9/10 absent, 10/11/12 thin. Oesophageal gizzard after viii. Intestinal origin at xv; caeca absent. Last hearts in xiii. Pharyngeal micronephridia developed in 5/6/7. Lymph glands absent. Typhlosole simple, lamelliform (segments 28–60).

Spermathecae variable, about 20–39 altogether in v–vii: 4–11 in v, 8–15 in vi, and 8–15 in vii ( Table 2). Spermathecal ampulla egg-shaped; duct short, about one-third ampulla length. Diverticula as short as duct, attached to base of duct; distal part enlarged to be an opalescent seminal chamber. No accessory glands.

Holandric. Testis sacs developed in x, but poorly developed in xi, separated. Seminal vesicles well developed in xi, xii. Ovaries on septum 12/13 posteriorly; oviducts after 12/ 13 and well developed, opalescent on 13/14. Prostate glands deeply lobuled, paired in xvii–xix; prostatic ducts U-shaped, slightly bigger distally, associated with chambers. Accessory glands invisible in the male region.

Habitats

The species was only found in light clay soils with rich organic matters in fruit plantations.

Remarks

The new species is closely similar to its congener species, P. mekongmontis from Hon Me Mountain on the mainland. However, the new species is different from P. mekongmontis in size (length 95–191 mm, diameter 5.4–7.8 mm versus length 82–91 mm, diameter 3.2– 3.7 mm), position of spermathecal pores (dorsolateral 4/5/6/7 versus ventrolateral 4/5/6/7), location of spermathecal diverticula (attached to base of duct versus attached to middle duct), and genital markings in male region (a pair in xix versus two pairs in xvii and xix) ( Table 4). Additionally, the species is also distinguished from P. mekongmontis by its casts. Polypheretima insularis has tower-shaped casts (c. 20 cm high) made from small balls whereas P. mekongmontis has small, lower casts ( Figures 14 (e) and 15(j)).

Figures

Figure 14. Polypheretima mekongmontis Nguyen, Tran & Nguyen, 2014. (a) Male region (mp = male pore, gm = genital markings); (b) prostatic gland; (c) ventral view of spermathecal region (sp = spermathecal pore); (d) spermathecae (amp = ampulla, dv = diverticulum); (e) casts. Scale bar = 1 mm for (a–d), and = 10 mm for (e).

Figure 15. Polypheretima insularis sp. nov. Holotype. (a, f) Male region (mp = male pore, gm = genital markings); (b, g) prostatic gland; (c, e) spermathecae (amp = ampulla, dv = diverticulum); (d) dorsal view of spermathecal region (sp = spermathecal pore); (h) male porophores and accessory glands, transverse body section; (i) living adult; (j) casts. Scale bar = 1 mm.