Metaphire manipurensis Tiwari & Yadav, 2025

Metaphire manipurensis Tiwari & Yadav sp. nov.

urn:lsid:zoobank.org:act:308905B1-AB28-46ED-852B-DEB96A3A5C12

Material examined: Holotype: One clitellate worm (2–3 segment removed to obtain DNA from the posterior region) MNP17-1154-47A3 , (reg no— ZSI CZRC T/20 ), natural forests location coordinates-24º83'76"N; 93º87'4"E, elevation- 844.306m, Lamdeng Makhaleikai Forest Range , Manipur, collected on- 12 th of October, 2017 ; Paratypes: One mature worm (caudal segment taken for DNA extraction), MNP17-988-39A5 , (reg no. DHSGV-ZDM- 272016015 ), location coordinates-24º37'28"N; 93º70'97"E, Churachandpur, Manipur, collected on- 6 th of October, 2017; One mature worm (caudal segment taken for DNA extraction), MNP17-1052-42A11 , (reg no. DHSGV-ZDM- 272016016 ), location coordinates-24º25'42"N; 94º29'92"E, elevation 418.8m, Yangoupokpi-Lokchao Wildlife Sanctuary , Manipur, collected on- 8 th of October, 2017; One mature worm (anal segment taken for DNA extraction), MNP17-1155-47 A4, (reg no. DHSGV-ZDM- 272016017 ), data same as for holotype; Other examined specimens are- one clitellate worm (anal part taken for DNA extraction) MNP17-940-36A2, location coordinates-24º54'75"N; 93º85'21"E, elevation 748.903m, Keibul Lamjao National Park , Bishnupur, Manipur, collected on- 3 rd of October 2017; one clitellate worm (caudal part taken for DNA extraction) each, MNP17-986-39A3 , MNP17-991-39A8 , data same as paratype MNP17-988-39A5; one clitellate worm (caudal part taken for DNA extraction) MNP17-1141- 46A5 , Paddy fields , location coordinates-24º83'59"N; 93º95'00"E, elevation 815.655m, Heingang, close to Imphal river , Manipur, collected on- 12 th of October, 2017; One complete worm each of MNP17-1154-47A3, MNP17-1155- 47A4, and one clitellate worm (caudal part taken for DNA extraction) MNP17-1170-47A20 , data same as holotype; one clitellate worm (caudal part taken for DNA extraction) MNP17-1084-44A10 , location coordinates-24º38'31"N; 94º14'92"E, Yangoupokpi-Lokchao Wildlife Sanctuary , Tengnoupal, Manipur, collected on- 10 th of October, 2017; collected by- Shweta Yadav .

Diagnosis: Mature specimen dimensions ranges from 80–210 mm Length, 4.5–4.8 mm width, segments 61– 123. Prostomium open-epilobic. The first dorsal pore is located in segments xi/xii, while the male pores are situated within a copulatory pouch in segment xviii. The intersegmental furrow of vi/vii/viii/ix contains three pairs of spermathecal pores, situated lateroventrally. Intestinal caeca originate in segment xxvii. Holandric. Prostate glands racemose. Spermathecae uni-diverticulate, nephridia on spermathecal duct absent. Stalked genital marking glands present near spermathecae.

Description: Length 80–210 mm, diameter 4.5–4.8 mm, segments 61–123 (n=11). Live worm with dark pigmented discrete clitellum.Dark pigmented dorsum, ventrally pale, unpigmented equators. Discrete intersegmental furrow visible only in the preclitellar region. Prostomium open epilobic ( Fig. 2a View FIGURE 2 ). Setae evenly distributed around segmental equators, the number of setae on vii-31, xx-48, with dorsal and ventral gaps while dorsal gap is relatively wider. First dorsal pore on xi/xii. Spermathecal pore three pairs in intersegmental furrow of vi/vii/viii/ix; ventral distance between spermathecal pores approximately 0.43x body circumference with slight thickened lips ( Fig. 2b View FIGURE 2 ). The clitellum forms an annular covering spanning three segments, from xiv to xvi. Female pore single median on segment xiv. Male pore in copulatory pouches on xviii opens with transverse slit-like aperture, 0.27x the circumference apart ventrally ( Fig. 2c View FIGURE 2 ). Additionally, there are 12–14 setae located between the male pores. In the male genital region segment xviii expanded laterally, a specific oblong shape in all collected specimens, epidermis surrounding the male pore wrinkled. Genital marking absent.

Septa 5/6 membranous, 6/7, 7/8 thickened, 8/9, 9/10 lacking, 10/11, 11/12, 12/13, 13/14 slight muscular and 14/15, 15/16 membranous. Dense tufts of nephridia in 4/5 and 5/6 on anterior faces of body wall, the nephridia of the intestinal segments are positioned on the body wall at both the anterior and posterior faces of the septa. Gizzard large in segment ix–x. Intestine begins in segment xiv, while the caeca originate in segment xxvii and extend up to segment xxii ( Fig. 2e View FIGURE 2 ). Heart located in segments xi–xiii. Ovaries and funnels are free in segment xiii. Spermathecae three pairs, post septal, nephridia on parieties near spermathecal duct apprehends the presence of nephridia on spermathecal duct, ampulla obovate or ovate with narrower fissured base, duct stout, conical, muscular with flat top, a stalked diverticulum is connected to the ectal part of the duct, long stalk terminating in a zigzag looped swollen receptacle ( Fig. 2f,g View FIGURE 2 ). Male sexual system holandric, with testes and funnels enclosed in paired sacs located in segments x and xi. Seminal vesicles situated in segments xi and xii, while the vas deferens is slender and attached to the body wall on its way to the ental end of the prostatic ducts. Prostates lie in segments xvii to xxi, each consisting of a single, dense, racemose mass ( Fig. 2d View FIGURE 2 ). A long, curved duct enters the lateral margin of the copulatory bursa. Paired small oval copulatory bursae present in segment xviii, each with two pads; the anterior pad bifurcated, posterior pad enlarged. Both pads contain a small lumen within glandular tissue. Penis absent. Genital marking glands club-shaped (cylindrical and enlarged gradually towards the end) long, stalked, two in vii, viii, and one in xi, buried in parietes ( Fig. 2g View FIGURE 2 ).

Etymology: Named after the state of Manipur, where the species is widely distributed.

Variations: Minor, discrepancies were found in the structure of male pores; in holotype the aperture is transverse slit, whereas in the paratypes (MNP17-988-39A5, MNP17-1155-47A4) it was round shaped. Another variation observed was the presence of a slightly long, straight spermathecal duct in one of the paratype (MNP17-1052- 42A11).

Remark: This sexthecal species, distinguished by spermathecal pores on segments 6/7–8/9 and the absence of postclitellar genital markings, is a member of the houlleti species group, one of the largest within Metaphire . Sims & Easton (1972) originally described 40 species in this group, though nine were subsequently synonymized with M. houlleti ( Tiwari et al. 2024b) . In recent years, six additional species have been incorporated into the houlleti group, restoring the group’s total to approximately 40 species ( Bantaowong et al. 2016, Ng et al. 2018, Nguyen et al. 2022, Chanabun et al. 2023, Jin et al. 2024). Thirteen of these have been documented in India and neighboring countries of Southeast Asia, namely: M. harrietensis ( Stephenson 1925) and M. scitula ( Gates1936) from India, M. umbraticola ( Gates 1932) , and M. quadrigemina ( Gates 1932) from Myanmar; M. amplectens ( Michaelsen 1934) , M. dawydovi ( Michaelsen 1934) and Metaphire acampanulata Nguyen, Ly, Lam, Nguyen & Nguyen, 2022 from Vietnam; M. perichaeta ( Beddard 1900) , M. virgo ( Beddard 1900) , M. khaoluangensis Bantaowong & Panha, 2016 , M. khaochamao Bantaowong & Panha, 2016 and Metaphire songkhramensis Chanabun & Panha, 2023 from Thailand; and M. houlleti ( Perrier 1872) , which is widespread in East and South-East Asia.

The newly described species, M. manipurensis , shares similarities in body size and dimensions with M. scitula , M. perichaeta , M. virgo , M. acampanulata , and M. quadrigemina . However, the novel species M. manipurensis differs from M. amplectens in body size, with M. amplectens being smaller (body length 44–52 mm, diameter 2½–3½ mm, and 90–112 segments). M. manipurensis can be easily distinguished from other species within the group by the position of the first dorsal pore, which in M. manipurensis is located at segment 11/12. In contrast, the dorsal pore is positioned at 12/ 13 in M. harrietensis , M. scitula , M. quadrigemina , M. songkhramensis , M. khaoluangensis , M. khaochamao , and M. perichaeta , while in M. houlleti and M. hijauensis , it is found at 9/10 and 10/11, respectively.

The intestinal origin also provides a distinguishing feature. In M. manipurensis , the intestine begins at segment xiv, compared to segment xv in M. houlleti , M. harrietensis , M. umbraticola , M. songkhramensis , M. khaoluangensis , M. khaochamao , M. acampanulata , and M. hijauensis , and segment xvi in M. scitula , M. quadrigemina , and M. perichaeta .

The structure of the intestinal caeca further distinguishes M. manipurensis . In the new species, the caeca originate in segment xxvii and extend to segment xxii, while in M. houlleti , M. quadrigemina , and M. virgo , they extend from xxvii to xxv. In M. umbraticola , M. perichaeta , M. acampanulata , and M. hijauensis , they extend from xxvii to xxiv.

Additional unique characteristics of M. manipurensis include a transverse slit-like male pore aperture, distinguishing it from the C-shaped opening of M. houlleti . Moreover, the male genital region in segment xviii exhibits lateral expansion, with genital marking glands embedded in the parietes near the spermathecae, unlike M. houlleti , where these glands are attached to the spermathecae.

While the male pore of M. manipurensis resembles the transverse slit-like opening seen in M. scitula and M. quadrigemina , the absence of genital marking glands near the spermathecae differentiates these species. Furthermore, the spermathecae of M. manipurensis , characterized by their obovate or ovate ampulla with a fissured base and stout, conical muscular duct with a flat top, is a distinctive feature within the group. It also differs from M. dawydovi , which has flask-shaped ampullae with a small diverticulum.

A detailed comparison of morphological characters between the M. manipurensis sp. nov. and other closely related species are presented ( Table 2 View TABLE ).