Acanthodrilus doanus, Csuzdi & Pearlson & Pavlíček, 2017

Csuzdi, Csaba, Pearlson, Oren & Pavlíček, Tomás, 2017, New Acanthodrilus species from New Caledonia (Clitellata, Megadrili, Acanthodrilidae), Journal of Natural History (J. Nat. Hist.) 51 (31 - 32), pp. 1899-1912 : 1902-1904

Acanthodrilus doanus sp. nov.

Figure 2

Type material

Holotype. HNHM / AF5679 , clitellate adult, tail missing. New Caledonia, Mt. Do Nature Reserve (21.70° S, 165.98° E), mountain forest, 7 February 2014, leg. T. Pavlí Č ek and O. Pearlson . Paratypes: HNHM / AF5680 , three praeadult ex ., locality same as that of holotype.

Etymology

The species name refers to the type locality – Mount Do , New Caledonia .

Diagnosis

L. 50–60 mm. D. 3–4 mm. Average weight 0.3 g. No. segments 96. Colour red-violet. First dorsal pore in 12/13. Clitellum 14–½17, circular. Prostatic pores paired on small papillae, in 17, 19. Penial setae L. 2.4 mm, D. 0.075 mm, ornamentation scattered teeth. Spermathecal pores 7/8, 8/9 a–b. Muscular gizzard in 6, calciferous glands lacking. Last pair of hearts in 13. Spermathecae with long narrow duct and an equally long pear-shaped ampoule. The duct entally bears a small diverticulum filled with sperm-chambers. Genital setae lacking.

Description

Holotype. L. 45 mm, D. 4 mm, No. segments 74, tail missing.

Paratypes. The intact specimen 56 mm in length, 3 mm in diameter, No. segments 96. Colour red-violet. Prostomium tanylobous, the first dorsal pore occurs in the intersegmental furrow 12/13. Setae closely paired, setal formula after the clitellum aa:ab:bc:cd:dd = 6.7:1.2:6.7:1:15.2. The clitellum extends over segments 14–½17, circular ( Figure 2a ). Prostatic pores paired on small papillae in 17, 19. Male pores externally clearly visible on segment 18, in the laterally highly convex seminal grooves. Female pores paired on 14, small slits anterior to setae a–a. Spermathecal pores large, on small papillae in furrows 7/8, 8/9 between setae a–b. Nephridiopores aligned in setal line cd. A single oval, midventral genital papilla situated in 16/17.

Internal characters

All septa membranous. Oesophageal gizzard large in 6. Calciferous glands lacking, intestine begins in segment 19. Typhlosole as large undulating lamella begins around segment 27. Excretory system holoic, nephridial bladders biramous ( Figure 2b ). Paired hearts are present in segments 10–13. Testes are in 10, 11 enclosed in the cavity formed by the fused septa 9/10–11/ 12. Two pairs of seminal vesicles present in 9, 12. A pair of small ovaries pendent from the posterior face of the septum 12/13. Two pairs of prostates present in 17, 19. The glands are long, reaching up to segment 22. Each prostate accompanied by a penial setal sac containing an adult and several replacement setae. The adult seta 2.7 mm in length and the middle 0.1 mm wide, tip pointed, slightly undulating, the ectalmost part bent at a right angle. Ornamentation consists of scattered small teeth ( Figure 2c ). Two pairs of spermathecae present in segments 8 and 9. Each consists of a narrow and long duct and an equally long, pear-shaped ampoule. The ental part of the duct bears a small diverticulum containing several small sperm chambers ( Figure 2d ). Genital setae lacking.

Remarks

The new species with its small size, red pigmentation, and vesicles in 9, 12 seems to be most close to A. canalanus Michaelsen, 1913 . However, it differs from the latter in the position of the clitellum (14–½17 vs. 13–17) and the form of penial setae (tip pointed vs. flattened). It is also remarkable that the nephridial bladders of the new species are not J-shaped as usual in the genus Acanthodrilus but show a typical biarmous appearance ( Figure 2b ).

Figures

Figure 2. Acanthodrilus doanus sp. n. (a) ventral view of the clitellar region; Fp, female pore; Gp, genital papilla; Mp, male pore; Prp, prostate pores; scale bar 2 mm. (b) nephridial bladder from the postclitellar segments. (c) penial seta; scale bar, 0.1 mm. (d) spermatheca.