Eutyphoeus phawngpuiensis, Tiwari & Lone & Thakur & James & Yadav, 2021

Tiwari, Nalini, Lone, Azhar Rashid, Thakur, Samrendra Singh, James, Samuel W. & Yadav, Shweta, 2021, Three uncharted endemicearthworm species of the genus Eutyphoeus (Oligochaeta Octochaetidae) from Mizoram, India, Zootaxa 5005 (1), pp. 41-61 : 46-48

Eutyphoeus phawngpuiensis sp. nov.

urn:lsid:zoobank.org:act:CB351D9C-03D8-4D71-B200-98B63669CEC0

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Material examined. Holotype: One mature (complete body), ( MZ17-574 - 1 A, IEW528-17 ), (Registration number: DHSGV-ZDM-H001), natural forests (22º67’06” N; 93º03’41”E) Phawngpui Blue Mountain National park Lawngtlai district towards the southeast of Mizoram, close to river Chhimtuipui , 1 August 2017, coll. Shweta Yadav. Paratypes: One mature (2–3 segment taken from anal part for DNA extraction) ( MZ17-574 - 1 A1), data same as for holotype ; 2 clitellate specimen ( MZ17-700 - 23 A20), grasslands (22º 70’87” N; 93º 01’11”E) Cheural village sector-Saiha, Mizoram, data same as for holotype. 1 mature (caudal segment taken for DNA extraction) ( MZ17- 609 - 6 A2), natural forests, (22º63’81”N; 93º02’44”E) Phawngpui Blue Mountain National Park , close to the peak of blue mountain, Mizoram, data same as for holotype . Paratypes (Registration number: DHSGV-ZDM-272016005), Bold accession number—ADL0658.

Diagnosis. Length 119–187 mm, diameter 4–4.9 mm, segments 130–160. Prostomium tanylobic. First dorsal pore in xi/xii. Male pores in xvii. A single pair of spermathecal pores in intersegment 7/8 at ab. Pair of genital markings present ventrally in segments ix/x/xi/xii/xvi at ab and at a on xviii/xix/xx/xxi. Septa 6/7/8 absent. Intestinal caeca broadly tubular. Holandric, seminal vesicle in xii not extends much. Four pairs of supra-intestinal glands. Prostate glands tubular, paired in xvii to xxi; ducts twisted and directly attached to body wall. Bidiverticulate spermathecae. Penial setae with slightly curved and pointed tip.

Description. External characters: Body cylindrical, length 119–187 mm, diameter 4–4.9 mm on clitellum, segments 130–160. Prostomium tanylobic. Colour, pigmented brownish, anterior seven segment relatively darkly pigmented while first two segment faded in live sample. First dorsal pore on intersegmental region of xi/xii. Clitellum annular, extends up to four segments i.e., 1/3xiii–xvii. Setae originates from segment iii, arranged regular, uniform throughout the body, setal arrangement aa = 2 ab = 0.5 bc = 1.4 cd = 0.1 dd on xii, aa = 3.2 ab = 1.7 bc = 2.5 cd = 0.15 dd on xxiv. One pair of spermathecal pores with transverse slit openings on intersegment 7/8 at ab. Female pore on segment xiv, between setae aa, presetal, paired, visible in the form of an elongated oval circle of light color. Male genital region avestibulate, pores discharges through transverse aperture on porophores in xvii on setal arc of b or lateral to b. Porophores encircled by thick elliptical projected mass with tapering ends. A distinct groove visible between both projected areas carrying male pores. Genital markings paired, postsetal on segments ix/x/xi/xii/xvi at ab, and paired, postsetal at a on xviii/xix/xx/xxi.

Internal characters: Septa 4/5/6 thickened, muscular, septa 6/7/8 absent and 8/9/10 relatively less thickened. Septa 8/9 and 9/10 pulled backwardly. Oesophagus with a single gizzard in segments between v/vi and viii/ix. Dorsal blood vessel complete, extends anterior to gizzard in segment iii. A pair of discrete intramural calciferous glands in xii. Intestine begins in segment xv. Last pair of heart in segment xiii. Lateral intestinal caecae on segment xxvii paired, dorsally directed, broadly tubular. Median ventral caecae unpaired, 18 in number from segments xxxiii–l, supra-intestinal glands 4 pairs in lxxi–lxxv. Typhlosole originate from segment xxvii, simple, lamelliform. Testis holoandric, seminal vesicle in ix and xii, later one extends up to segment xiv, prostate tubular extending from xvii to xxi, ducts twisted and directly attached to body wall ( Fig. 2f ). Spermathecae paired, bidiverticulate, each with a multiloculate shortly stalked ental diverticula. Both diverticulum opens into a duct through a single opening, duct short and stout. Penial setae 1.30–2.16 mm long, 44–53µm diameter, smooth, tip pointed and slightly curved ( Fig. 2i ), 3–4 penial setae per battery. Genital marking gland absent.

Etymology. “ phawngpuiensis ” is derived from its type habitation the Phawngpui Blue Mountain National park, Mizoram.

Variations. The main variations observed between holotype and paratypes are in position of genital markings such as: in holotype the genital marking is present as paired, postsetal on segments ix/x/xi/xii/xvi at ab, and paired, postsetal at a on xviii/xix/xx/xxi segments. While in paratypes, sometimes genital marking on segment viii paired, postsetal at ab or sometimes genital marking on segments xix/xx/xxi were absent. Other variation observed were in female pore, in holotype female pore was clearly visible while in paratypes the position of pore was unclear.

Remarks. The new species can be categorized into the Eutyphoeus hastatus group ( Gates 1958) characterized by pair of spermathecal pores in 7/8 at ab, avestibulate male pores, holandric testes, short seminal vesicles in xii and a complete dorsal blood vessel. It is discriminated from other species of the group by bidiverticulate spermathecae, spermathecal pore at ab in 7/8, arrangements of genital markings and absence of genital marking glands ( Table 3).

Figures

FIGURE 2. Eutyphoeus phawngpuiensis sp. nov. Holotype (a) field photograph; (b) prostomium; (c) spermathecae (d) spermathecal pore and pre-clittelar genital markings; (e) male and female pore; (f) prostate; (g) lateral intestinal caeca (lic); (h) supra-intestinal gland; (i) penial setae; (j) illustration of genital region.