Eutyphoeus serei, 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 : 48-50

Eutyphoeus serei sp. nov.

urn:lsid:zoobank.org:act:056FC3BB-0AB3-4F20-8AFC-967730452F48

( Fig. 3 )

Material examined. Holotype: One mature (complete body), ( MZ05 A160405, IEW092-17 ), (Registration number— ZSI CZRC A.20049), natural forests (24°05’08”N; 92°48’02”E) Dampa Tiger Reserve Forest , range terei, village serei, Mizoram. 28 September 2016, coll. Samuel W James & Shweta Yadav. Paratypes: One mature (caudal segment taken for DNA extraction) ( MZ05 A170406, MZ05 A210410), data same as for holotype . Paratypes (Registration number— DHSGV ZDM 272016006 ), Bold accession number —ADH3131 .

Diagnosis. Length 170–180 mm, diameter 5.6–6 mm, segments 130–150. First dorsal pore in xi/xii. Female pore single on left side in xiv.Avestibulate, male pores in xvii. Pair of genital markings present ventrally in segments vii (postsetal), viii (presetal) at a, xvi (postsetal) lateral to b, xviii (postsetal at ab), sometimes on xix post setal at a. Septa 6/7/8 absent. Lateral intestinal caeca simple in xxviii. Metandric. 5–6 pairs of supra-intestinal glands. Prostate glands tubular, paired in xvi to xxiii–xxv. Bidiverticulate spermathecae. Penial setae with spoon shaped tip and pointed ends.

Description. External characters: Length 170–180 mm by 5.6–6 mm on clitellum, segments 130–150. Prostomium (evanescent shape, bit distorted during preservation). Colour dark caramel. First dorsal pore intersegmental in xi/xii. Clitellum annular, extends up to four segments i.e., 1/3xiii–xvii. Setae originates from segment iii and setal arrangement are aa = 2.5 ab = 1.3 bc = 1.5 cd = 0.08 dd on xii, aa = 3 ab = 1.6 bc = 1.7 cd = 0.1 dd on xxiv. Spermathecal pores one pair on intersegmental region of 7/8, transverse slits like opening or small oval papillae at ab or lateral to b. Female pore single on segment xiv, single on left side at setal line a. Male genital region avestibulate, male pore discharges on the surface through the slit like aperture on protruded dark coloured porophores on segment xvii lateral to setal arc of b. Both porophores are thick short tubular outwardly focussed with centric male pores. Genital markings paired on vii (postsetal), viii (presetal) at a, viii (postsetal) at ab, xvi (post setal) lateral to b just above the encircled area of male genital region, a unique paired elongated marking having two small circular protuberance on xviii (post setal at ab), sometimes on xix post setal at a.

Internal characters: Septa 4/5/6 thickened, muscularized, septa 6/7/8 absent and 8/9/10 relatively less thickened, muscular. Oesophagus contains a single gizzard between v/vi and viii/ix. Dorsal blood vessel complete, extends anterior to gizzard in segment iii. Discrete intramural calciferous glands in xii. Intestine begins in segment xv. Last pair of heart in segment xiii. Lateral intestinal caecae paired, conical in shape, ventrally directed in xxviii. Median ventral caecae unpaired, 5–6 in number from segments xxxi–xliii, Supra-intestinal glands 5–6 pairs in segment lxxxi–lxxxv. Typhlosole begins from xxvi simple, lamelliform. Testis metandric, seminal vesicle extending upto xvi. Prostate tubular occupy xvi to xxiii–xxv. Spermathecae paired, bidiverticulate, each with a 2.5–2.8 mm long multilobulated, dorsally directed ectal diverticula, both diverticulum opens into a duct through a separate opening, smaller in size in comparison to ampullae, ampulla cylindrical in shape, duct short. Penial setae 2–3mm long, without ornamentation, tip spoon shape with pointed ends ( Fig. 3i ). 1–3 penial setae per battery. Genital marking gland absent.

Etymology. “ serei ” is derived from the Serei village in which the type’s habitation is found.

Variations. The variations were observed in shape and position of spermathecal pores. In holotype, the spermathecal pore opens with a transverse slits on intersegmental region of 7/8 at b extending towards a while in one of its paratypes, spermathecal pore was present on a small oval papilla on intersegmental region of 7/8 at b extending towards lateral to b. Genital marking were present on segment xviii; holotype has two small circular protuberance within an elongated markings, while one of the paratypes has paired elongated markings with four small circular protuberances.

Remarks. The new species belongs to the Eutyphoeus gigas group ( Gates 1958) characterized by pigmented body, presence of first dorsal pore on xi/xii, single female pore on left side female pore of right side absent, presence of lateral intestinal caeca and numerous ventral caeca. The dorsal blood vessel is aborted and anterior testes along with the funnels of segment x and their ducts is absent. It is distinguished from other species of the group E. gigas Stephenson, 1917 by presence of spoon shaped tip of penial setae with lack of any kind of ornamentation and absence of genital marking glands ( Table 3).

Figures

FIGURE 3. Eutyphoeus serei sp. nov.. Holotype (a) field photograph; (b) spermathecal pore; (c) clitellar region, male pore and female pore; (d) male genital region; (e) prostate; (f) lateral intestinal caeca; (g) supra-intestinal glands; (h) spermathecae; (i) penial setae; (j) illustration of male genital region.