Eutyphoeus tawi, 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 : 50-52

Eutyphoeus tawi sp. nov.

urn:lsid:zoobank.org:act:03F4A708-E65C-4BC6-85EE-88AF94986FB9

( Fig. 4 )

Material examined Holotype: One mature (caudal segment used for DNA extraction), ( MZ016 A150570, IEW257- 17 ), (Registration no. ZSI CZRC A.20050), natural forests (23°54’89”N; 92°91’52.6”E) Tawi Wild Life Sanctuary , core area, Hualtu, Mizoram, India, 12 October 2016, coll. Samuel W James & Shweta Yadav. Paratypes: 1 mature (caudal segment used for DNA extraction) ( MZ013 A10517 ), natural forests, (23°53’43”N; 92°91’27”E) Tawi Wild Life Sanctuary , dense and deeply rooted trees, rich in humus, close to pond, Mizoram, India, 9 October 2016, coll. Samuel W James & Shweta Yadav. 2 clitellate ( MZ014 A90537), close to river Chalkhawhkawn, (23°56’39”N; 92°92’91”E) Tawi Wild Life Sanctuary Hualtu, Mizoram, India, 10 October 2016, coll. Samuel W James & Shweta Yadav. One mature (amputated postclitellar region) ( MZ016 A160571), data same as for holotype. (Registration number DHSGV ZDM 272016007 ). Bold accession number-ADG9128 .

Diagnosis. Length 130–150 mm, diameter 3.9–5 mm, segments 100–110. Prostomium tanylobic. First dorsal pore in xi/xii. Spermathecal pores paired in 7/8 thick muscular encircle, lateral to b. Bivestibulate, male pores present in a deep quadrangular depression/fissure in xvii. Genital markings absent. Septa 6/7/8 aborted. Lateral intestinal caecae absent. Holandric, seminal vesicle in xii not extends much. 4 pairs of supra-intestinal glands. Prostate tubular, compact. Ornamented, spoon shaped tip of penial setae slightly bent on the end. Bidiverticulate, bulbous end spermathecae.

Description. External characters: Length 130–150 mm with 3.9–5 mm of diameter. Segments 100–110. Prostomium tanylobic. Colour barn red, slightly lighter on ventral side. First dorsal pore on intersegmental region of xi/xii. Clitellum annular, extends up to five segments i.e., from xiii–xvii. Setae aa = 2 ab = 1.16 bc = 3.2 cd = 0.23 dd on xii, aa = 2.5 ab = 1.3 bc = 1.92 cd = 0.28 dd on xxiv. Spermathecal pores paired in 7/8 with transverse slit like opening well marked with thick muscular encircle, lateral to b. Female pores on segment xiv, paired, minute, pre-setal at a. Male genital region bivestibulate, male pores present in a deep quadrangular depression/fissure which sometimes appears single however, distinctly located in a separate vestibule in xvii. Lateral side of clitellar region projected into a ventrally directed fold. In live sample both fold touches each other in the centre. Genital markings absent.

I nternal characters: Septa 4/5/6 muscular, 6/7/8 aborted and 8/9–10/11 thickened. Oesophagus with a single large gizzard in segments between v/vi and viii/ix. A pair of discrete intramural calciferous gland in segment xii. Dorsal blood vessel complete, extends anterior to gizzard in segment iii. Lateral intestinal caecae absent. Median ventral unpaired caecae 6–7, in segments xxxiii–xli, supra-intestinal glands 4 pairs in segments lxiv–lxix. Typhlosole simple lamelliform in xxvii–lxxvii. Holandric, seminal vesicle in ix and xii, those of xii extending upto xiv. Prostate tubular, compact, extending upto xix. Penial 3.84 mm long, ornamented with irregular interrupted circles of fine spines, a spoon shaped depression just posterior to tip, which is curved with and have a blunt end, 2–3 penial setae per battery. Spermathecae paired, bidiverticulate, bulb like terminals of two lateral diverticulae, with circular or spheroidal ampulla. Genital marking glands absent.

Etymology. “ tawi ” is derived from Tawi Wild Life Sanctuary in which the habitation of its type is found.

Remarks. The species belongs to the Eutyphoeus hastatus group ( Gates 1958) characterized by holandric testis, bidiverticulate spermathecae, spermathecal pores at b or lateral to b and complete dorsal blood vessel. This species is distinguished by other species of the group such as E. manipurensis manipurensis , E. mizoramensis and E. hastatus mainly by position of spermathecal pores on intersegmental region of 7/8 lateral to b, vestibulated male genital region, lack of lateral intestinal caecae and absence of genital marking. While, it shows a close resemblance with E. marmoreus the main distinguishing character is lack of lateral intestinal caecae and spoon like depression of penial setae, just posterior to tip and terminates into a blunt end. E. marmoreus is a species not yet reported in India, it is known from its type locality Tedim (Chin Hills), Myanmar. Due to the close proximity of the locality i.e., Mizoram shares its border with Myanmar therefore included for comparison.

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Figures

FIGURE 4. Eutyphoeus tawi sp. nov.. Holotype (a) Field photograph (b) spermathecal pore; (c) male and female pore region; (d) magnified view of male genital region; (e) supra-intestinal glands; (f) median unpaired ventral caecae; (g) prostate; (h) tyhlosole; (i) spermathecae; (j) penial setae; (k) illustration of genital regions.