Kanchuria tripuraensis Narayanan, Paliwal & Julka, 2025

Narayanan, S. Prasanth, Paliwal, R., Kurien, Vijo T., Nath, Sabyasachi, Dey, Animesh, Nandy, Subhrajit, Kar, Prithwiraj, Goldar, Sujata, Thomas, A. P. & Julka, J. M., 2025, Description of two new Kanchuria Julka, 1988 (Clitellata: Megascolecidae) species of earthworms from Tripura State, North-eastern India, Zootaxa 5647 (2), pp. 101-116 : 103-107

Kanchuria tripuraensis Narayanan, Paliwal & Julka , sp. nov.

( Figures 1A–B , 2A–F , 3A–D )

Type material. Holotype: Clitellate ( ZSIK Reg. No. ZSI/WGRC/I.R.INV.28502), Lankamura (23.8638° N, 91.2461° E), ca. 5 km northwest of Agartala city, West Tripura District, Tripura State, India, 29 m a.s.l., wooded area, 6 July 2024, collected by S. Prasanth Narayanan, Vijo T. Kurien, Prithwiraj Kar and Subhrajit Nandy. Paratypes: 2 clitellates ( ZSIK Reg. No. ZSI/WGRC/I.R.INV. 28503), Jangalia (23.6681° N, 91.2965° E), ca. 2.5 km southeast of Bishalgarh town, Sepahijala District, Tripura State, India, 49 m a.s.l., Hevea brasiliensis plantation, 6 July 2024, collected by S. Prasanth Narayanan, Vijo T. Kurien, Prithwiraj Kar and Subhrajit Nandy ; 1 clitellate ( ZSIK Reg. No. ZSI/WGRC/I.R.INV. 28504), Udaipur (23.5443° N, 91.4676° E), Gomati District, Tripura State, India, 22 m a.s.l., Hevea brasiliensis plantation, 8 August 2005, collected by Sabyasachi Nath.

Other materials. Altogether 36 specimens. 4 clitellates, 1 aclitellate (Reg. No. ACESSD /EW/1772.) (mainly anterior portions), same collection data as for holotype ; 4 clitellates (Reg. No. ACESSD /EW/1773) (mainly anterior portions), same collection data as for 1 st paratype ; 1 clitellate (Reg. No. ACESSD /EW/1774), Jangalia (23.6683° N, 91.2933° E), Sepahijala District, Tripura State, India, 49 m a.s.l., Hevea brasiliensis plantation, 5 July 2024, collected by S. Prasanth Narayanan, Prithwiraj Kar, Subhrajit Nandy, Priyasankar Chaudhuri, Animesh Dey, Vijo T. Kurien, and Sujata Goldar ; 5 clitellates (Reg. No. ACESSD /EW/1775), same collection data as for 2 nd paratype ; 4 clitellates, 1 aclitellate (Reg. No. ACESSD /EW/1776), Kamalpur , Dhalai District, Tripura State, India, Hevea brasiliensis plantation, 11 September 2006, collected by Sabyasachi Nath ; 2 clitellates (Reg. No. ACESSD /EW/1777), Khowai , Khowai District, Tripura State, India, Hevea brasiliensis plantation, 12 September 2005, collected by Sabyasachi Nath ; 5 clitellates, 1 aclitellate (Reg. No. ACESSD /EW/1778), Agartala , West Tripura District, Tripura State, India, sawdust dumping site and bamboo ( Bambusa sp. ) plantation, 12 July 2015, collected by Susmita Debnath ; 2 clitellates (Reg. No. ACESSD /EW/1779), Kailashahar (Koilasohor), Unakoti District, Tripura State, India, Hevea brasiliensis plantation, 12 October 2006, collected by Sabyasachi Nath ; 6 clitellates (Reg. No. ACESSD /EW/1780), Bishalgarh , Sepahijala District, Tripura State, India, Hevea brasiliensis plantation, 1 September 2005, collected by Sabyasachi Nath.

Diagnosis. Medium sized worm; length 170–273 mm, width (mid-clitellar) 4.5–7 mm, 294–457 segments. First dorsal pore at intersegmental furrow 10/11. Clitellum annular on segments ½13, 14–17 (= 4½), intersegmental furrows indistinct, seta visible or indication present. Spermathecal pore single, segmental, in midventral line, on posterior margins of segments 7 and 8. Male field a central depression, on segments 18 and 19, with varying levels of elevated margins, male pores minute, closely paired on porophores, at anterior ends of seminal grooves, on mid-ventral line; seminal grooves paired, U-shaped. Genital marking discrete, single, median, intersegmental on 18/19. Female pore single, minute. Intestine origin in segment 15. Metandric. Prostates paired, extends in segments 18–20. Spermathecae single, on segments 7 and 8, ampulla large, ovoid or ovoid-sac, narrowed entally; ampulla and duct indistinctly marked off; unidiverticulate, club-shaped, ental diverticulum, diverticulum shorter than ampulla. Genital marking glands absent.

Description. External. Pale at anterior with rose tint, greyish appearance posteriorly with light reddish tinge; body circular in cross section; irregular bulging present on body towards posterior end. Dimensions: Holotype: length: 273 mm, width (mid-clitellar): 6 mm, 361 segments; paratypes: length: 171–249 mm, width (mid-clitellar): 4.5–6 mm, 294–457 segments; other materials: length: 170–248 mm, width (mid-clitellar): 4.5–7 mm, 325–403 segments. Prostomium prolobic, retracted, peristomium with several longitudinal striations. Segments 1–3 monoannulated, segments 4–13 bi or tri-annulated, behind clitellum tri or quadri-annulated; setal arc on elevated ridge. First dorsal pore at intersegmental furrow 10/11. Setae small, lumbricine, closely paired, present on segment 2; setal formula aa = 3.4–4 ab = 0.89–1 bc = 2.43–4 cd = 0.09–0.1 dd at segment 12 and aa = 2.62–3.2 ab = 1–1.6 bc = 1.6–2.62 cd = 0.13–0.17 dd at segment 24 (n = 2). Clitellum tumescent, annular on segments ½13, 14–17 (= 4½), colour pale yellowish buff or brownish, dorsal pores occluded, intersegmental furrows indistinct, seta visible or indication present. Spermathecal pore single, segmental, in midventral line, conspicuous or lightly conspicuous, on lightly elevated area with central aperture, on posterior margins of segments 7 and 8, in front of intersegmental furrows 7/8 and 8/9, between aa setal lines ( Fig. 1A, B ). Male field a central depression, on segments 18 and 19, with varying levels of elevated margins ( Fig. 2A–F ), male pores minute, closely paired, on slightly raised porophores, at anterior ends of seminal grooves, on mid-ventral line, between aa setal lines ( Fig. 2A–B ); seminal grooves paired, straight or lightly diagonally placed, diverging posteriorly up to the middle then straight and posterior ends convergent (Ushaped) to a single pore of an unpaired genital marking, on 18/19. Female pore single, minute, indicated by faint whitish transverse depression, presetal, ventro-median, at aa setal lines, on segment 14. Genital marking discrete, single, median, oval or circular, transversely or longitudinally placed ( Fig. 2A–F ), on 18/19, at bb setal lines, with central aperture, larger than male pore. Nehridiopores not recognizable. Penial setae absent.

Internal. Unpigmented. Septum 5/6 delicate, septa 6/7–10/11 muscular, 11/12 lightly muscular. Oesophagus with large, muscular, barrel-shaped gizzard, in segment 5 (between septa 4/5 and 5/6), septa 6/7/8 pushed posteriorly in funnel-like manner, take the space of segments 6–8; oesophagus and gizzard attached to parietes with several crisscrossed muscular fibres, which pierce through the muscular septa; calciferous glands on segments 12 and 13; intestine origin in segment 15; intestinal caeca absent; typhlosole bifid entally. Dorsal blood vessel, single and complete.Last pair of hearts in segment 13. Metandric; testis and funnels, paired, free, in segment 11; seminal vesicles paired, racemose, in segment 12; ovaries paired in segment 13. Prostates paired in segment 18, thickly racemose, strap-shaped ( Fig. 3A–B ), fairly large, longitudinally placed, extends in segments 18–19, 20 ( Fig. 3B ), penetrating through the septa 18/19/20; prostatic duct short, thin, straight, transversely directed, equal width throughout, with light muscular sheen. Spermathecae single, in segments 7 and 8, on posterior margin, erect, ampulla large ovoid or ovoid-sac, narrowed entally, light transversely striped; ampulla and duct indistinctly marked off; unidiverticulate, club-shaped, ental diverticulum, projected from anterior or on lateral surface of duct, diverticulum shorter than ampulla ( Fig. 3C–D ). Genital marking glands absent.

Variations. In recently collected fresh specimens (specimens collected in 2024), setae on the clitellum are visible only at high magnification. In fresh specimens (collected in 2024), the spermathecal ampulla narrowed entally to a pointed end ( Fig. 3D ), but in old specimens it is narrowed but not much pointed (especially in 2 nd paratype ZSIK Reg. No. ZSI/WGRC/I.R.INV. 28504 and ACESSD/EW/1775). In one specimen, the prostate is twisted upwards and confined to segment 18 (ACESSD/EW/1776). Whereas many specimens showed ‘n-like’ bent in both prostates (ACESSD/EW/1776, 1778) and two specimens, prostate has bent in segment 19 and twisted upwards (ACESSD/ EW/1778). In certain specimens the prostates had deeply incised margins (ACESSD/EW/1776, 1780).

Etymology. The specific epithet ‘ tripuraensis’ is a toponym and refers to the Indian state of Tripura, from where the new species has been collected and described. Tripura is moderately rich with earthworm species; except for the new species described here, 36 species have been reported from the state ( Narayanan et al. 2023; Ahmed et al. 2025). This is the first earthworm species to be named after the state.

Ingesta . Mainly soil (chiefly sand particles and quartz) and sparse organic matter like rootlets, tiny pieces of bark, etc.

Habitat. In the present study, it has been mainly collected from plantations (rubber Hevea brasiliensis Müll. Arg. and bamboo Bambusa sp. ), wooded areas, and sawdust dumping sites, and the soil is sandy or silty loam with a pH range of 4.33–7.01. Common vegetation found at the type locality Lankamura is the following: Artocarpus sp. , Aquilaria malaccensis Lam. , Microcos paniculata L., Achyranthes aspera L., Melastoma malabathricum L., Curcuma longa L., Cida acuta Burm.f. , Scoparia dulcis L., Holarrhena pubescens Wall. ex G.Don. , Oplismenus compositus (L.) P.Beauv., Bambusa cacharensis R.B.Majumdar , Bambusa polymorpha Munro. , Paspalum fimbriatum Kunth , etc. Among these, Artocarpus sp. , Microcos paniculata , Achyranthes aspera , and Oplismenus compositus are the most dominant species. However, as part of various ecological studies conducted in Tripura State, this species has been recorded (as Kanchuria sp. 1 ) from cow dung heaps, mixed forests, pastures and various types of plantations (mixed fruit, pineapple, tea) (see Chaudhuri et al. 2012; Chakraborty et al. 2023).

Biology. It produces large towering casts on the soil surface.

Ecology. It seems to be an endo-anecic species, as indicated by the large quantity of fine soil, sand, and pieces of rootlets and bark in the intestine. K. tripuraensis sp. nov. was found to coexist with various native ( Drawida assamensis Gates, 1945 , D. nepalensis Michaelsen, 1907 , D. papillifer Stephenson, 1917 , Eutyphoeus comillahnus Michaelsen, 1907 , E. gigas Stephenson, 1917 , and K. priyasankari sp. nov.), and exotic ( Pontoscolex corethrurus ( Müller, 1857) , and Metaphire sp. ) earthworm species at different localities. For more details about the ecology of the species, see the works of Dey et al. (2012), Jamatia & Chaudhuri (2017), Chakraborty et al. (2020, 2023) etc., where it is referred to as ‘ Kanchuria sp. 1 ’.

Distribution. Endemic to India: widespread in Tripura State: Dhalai District: Kamalpur; Gomati District: Udaipur; Khowai District: Khowai; Sepahijala District: Bishalgarh, Jangalia; Unakoti District: Kailashahar (Koilasohor); West Tripura District: Agartala, Lankamura. It is collected from the border regions; hence, it can be found in the adjacent areas of Bangladesh.

Remarks. Kanchuria tripuraensis sp. nov. is a unique species among the various members of the genus. It can easily be distinguishable from all the other known species of the genus by having a single, segmental spermathecal pore at the midventral line of segments 7 and 8, in front of intersegmental furrows 7/8 and 8/9, and the entally bifid typhlosole. The rest of the species have paired spermathecal pores and simple lamelliform typhlosole.

Figures

FIGURE 1. Kanchuria tripuraensis sp. nov., A–B. Ventral view of anterior portion showing the locations of spermathecal pores. Abbreviation: Sp—Spermathecal pores.

FIGURE 2. Kanchuria tripuraensis sp. nov., A. Illustration of the male genital region, ventral view; B–F. Images showing the male genital region, ventral view. Abbreviations: Cl—Clitellum; Fp—Female pore; Gm—Genital marking; Mg—Male genital region; Mp—Male pore; Sg—Seminal groove.

FIGURE 3. Kanchuria tripuraensis sp. nov., A–B. Dorsal view of prostate, right side; C–D. Dorsal view of spermathecae dorsal view. Abbreviations: Pd—Prostatic duct; Pr—Prostate; Sa—Spermathecal ampulla; Sd—Spermathecal duct; Sdi— Spermathecal diverticulum; Se—Septum.