Troglobdella guizhouensis Liu & Nakano, 2025

Troglobdella guizhouensis Liu & Nakano sp. nov.

Etymology.

The genus name Troglobdella is derived from the Ancient Greek “troglos” meaning “cave” and “bdella” meaning “leech” referring to the genus’ trait to subterranean habitats. We suggest the Chinese formal name as “yǐn dòng zhì shǔ” (隐洞蛭属). The species name “ guizhouensis ” is based Guizhou Province in China, where the species was discovered, with the suffix “ - ensis ” indicating geographical origin. We suggest the Chinese formal name as “ guì zhōu yǐn dòng zhì ” (贵州隐洞蛭).

Material examined.

Holotype: GZ 20240501 ; body length 37.4 mm, maximum body width 4.5 mm, anterior sucker width 2.0 mm, posterior sucker width 4.9 mm. Collected from Chishui Cave, Yangjiao Group, Zhaoshan Village, Shanqiao Street , Caohai Town, Weining County, Guizhou Province, China ( 26°53'42"N, 104°19'59"E; elevation: 2334 m) on January 19, 2024 (Figs 1 View Figure 1 – 3 View Figure 3 ). GoogleMaps

Paratypes: Five specimens (GZ 20240502 - GZ 20240506), same collection data as for the holotype. The holotype is preserved intact, and the dissection of one paratype (GZ 20240506) is illustrated in Fig. 3 View Figure 3 . All type materials are deposited at the Engineering Research Center for Exploitation & Utilization of Leech Resources in Universities of Yunnan Province, Kunming University, Kunming, China.

Diagnosis.

Troglobdella guizhouensis can be distinguished from the other salifid genera as well as other species by the following combination of characters: body milky white with no pigments; without eyes; oral sucker well developed, distinctly laterally expanded; mid-body somites six-annulate; gonopores separated by four annuli; testisacs multiple; pharynx strepsilaematous; lacking preatrial loop of male paired ducts; paired atrial cornua conical, curved laterad; atrium short, globular; ovisacs descending to anterior of somite XIV, then turned several times in each of posterior parts, forming globular mass.

Description.

Aquatic predatory leech. Body firm and muscular, medium sized, gradually widening in caudal direction, length 38.1 ± 4.8 mm (n = 6), maximum body width 4.0 ± 0.3 mm, width of anterior sucker 2.3 ± 0.2 mm, width of caudal sucker 4.8 ± 0.5 mm. Caudal sucker diameter obviously wider than maximal body breadth (Fig. 2 A, B View Figure 2 ).

Annulation of somites I – VII comprising 15 annuli altogether; 1 st annulus completely merged with prostomium, then 2 nd (peristomium)> 3 rd – 15 th annuli; 6 th and 7 th annuli forming posterior margin of oral sucker. Somite VIII quinquannulate, a 1 (with obvious secondary furrow, b 1, b 2) + a 2 + b 5 + c 11 + c 12. Somites IX – XXIV sexannulate (Fig. 2 C – E View Figure 2 ), b 1 + b 2 = a 2 = b 5 = c 11 = c 12; in somites XI – XII, b 5 of each somite generally with slight secondary furrow. Annulation of somites XXV – XXVII comprising more than 8 annuli altogether; 120 th being last complete annulus on venter; anus between 120 th and 121 st annulus with more than 4 post-anal annuli. Accordingly, annulation of somites XXV – XXVII tentatively interpreted as follows (Fig. 2 E View Figure 2 ): somite XXV quadrannulate, b 1 + b 2 + a 2 + a 3 (b 5, b 6), a 3 being last complete annulus on venter; somite XXVI triannulate, a 1 (b 1, b 2) + a 2 + a 3; somite XXVII uniannulate; anus at somite XXV / XXVI with more than 4 post-anal annuli. Somite X b 5 and somite XIII a 2, respectively, first and last annuli of clitellum.

Male gonopore in posterior margin of somite XII b 2. Female gonopore in somite XII / XIII. Gonopores separated by four annuli (Fig. 2 C View Figure 2 ).

Anterior ganglionic mass in 10 th and 11 th annuli (somite VI b 5 and b 6). Ganglion VII in 13 th annulus (somite VII a 2). Ganglia VIII and XII, of each somite, in a 2 and b 5. Ganglia IX, XII, XV, of each somite, in a 2. Ganglia X, XIII, XIV, XVI-XX, of each somite, in b 2 and a 2. Ganglia XXI-XXIII, of each somite, in b 2. Ganglion XXIV in b 1 and b 2. Ganglion XXV in somite XXIV c 11. Ganglion XXVI in 117 th annulus (somite XXV b 1), coalescing with posterior ganglionic mass. Posterior ganglionic mass in 118 th - 121 st annuli (somite XXV b 2 - somite XXVI a 1).

Eyespots absent. Papillae numerous, minute, hardly visible, one row on every annulus, and two rows on annuli with secondary furrow.

Nephridiopores in 17 pairs, one each situated ventrally at posterior margin of a 1 of somite VIII, and at posterior margin of b 2 of each somite in IX-XXIV.

Pharynx strepsilaematous, reaching to somite XV b 1, with 3 myognaths separated by triangular paragnaths, each myognath bearing two minute stylets arranged longitudinally in tandem, parallel to body axis. Crop tubular acecate, reaching to somite XIX b 1; sphincter between crop and intestine undeveloped. Gastropore and gastroporal duct absent. Intestine tubular, thin-walled, acecate, reaching to XXIII b 5. Rectum tubular, thin-walled, reaching straight to anus.

Testisacs multiple, uncountable, on each side in somite XVII b 5 to XXIV b 2. Paired sperm ducts coiled, narrowing at junction with atrial cornua, then running proximally toward atrial cornua; both sperm ducts in somite XII b 2 to somite XVII b 5. Pair of atrial cornua conical, curved laterad, in XII b 2 and a 2 (Fig. 3 View Figure 3 ). Atrium short, muscular, globular, in XII b 2 and a 2. Penis sheath and penis absent.

One pair of ovisacs, thin walled, slightly folded, tubular, descending to anterior of somite XIV, both ovisacs turned several times in each of posterior parts, forming globular mass (Fig. 3 View Figure 3 ); in GZ 20240504, right ovisac turned anteriorly in XIV a 2, then reaching to XIV b 2 and turned posteriorly, descending again to XIV a 2, left ovisac turned anteriorly in XIV b 2, then reaching to XIII c 12 and turned posteriorly, descending again to XIV b 2; both ovisacs, in XIII b 2, turned proximally towards female gonopore, converging in anterior margin of XIII b 1 and then directly descending to female gonopore.

Habitat.

Troglobdella guizhouensis was found in shallow puddles approximately 30–50 meters from the entrance of Chishui Cave. The species likely feeds on aquatic invertebrates such as insect larvae and may burrow into sediment to avoid desiccation during dry periods or winter months.