Tritetrabdella longiducta, Nakano & Jeratthitikul & Nguyen & Panha, 2016

Nakano, Takafumi, Jeratthitikul, Ekgachai, Nguyen, Tao Thien & Panha, Somsak, 2016, A new species of Tritetrabdella (Hirudinida: Hirudiniformes: Haemadipsidae) from northern Indochina, Raffles Bulletin of Zoology 64, pp. 105-116 : 107-111

publication ID	https://doi.org/ 10.5281/zenodo.5354972
publication LSID	lsid:zoobank.org:pub:3B918034-7C31-4D51-81AA-E1C06142C38F
persistent identifier	https://treatment.plazi.org/id/1DF1A03F-A5A6-4021-8221-7AB1F2FCFCD6
taxon LSID	lsid:zoobank.org:act:1DF1A03F-A5A6-4021-8221-7AB1F2FCFCD6
treatment provided by	Valdenar
scientific name	Tritetrabdella longiducta
status	sp. nov.

Treatment

Tritetrabdella longiducta , new species

( Figs. 2–5 View Fig View Fig View Fig View Fig )

Material examined. Holotype: hermaphrodite ( CUMZ 5100 View Materials ), dissected, Doi Phuka , Tambon Phu Kha, Nan Province, Thailand (19.201306°, 101.082250°; elevation 1286 m), coll.

E. Jeratthitikul, 13 October 2013. Paratype: hermaphrodite ( VNMN 04733 View Materials ), dissected, Ta Co , Sop Cop District, Son La Province, Vietnam (20.96°, 103.6°; elevation 720–920 m), coll. T. T. Nguyen, 15 September 2014 .

Diagnosis. Caudal sucker circular, with 57 friction rays. Somite VII triannulate, somites VIII–XXII quadrannulate, somite XXV uniannulate. Somites XXV–XXVII forming respiratory auricles. Male gonopore in somite XI b5/b6, female gonopore slightly anterior to middle of somite XII b5, gonopores separated by 3 + 1/2 annuli. Jaws trignathous, each jaw without salivary papillae. Paired epididymides in somite XIII b6 to somite XIV a2, occupying more than one full somite; from each epididymal mass, thick sperm ducts reaching to each ejaculatory bulb. Ejaculatory bulbs ellipsoidal, in somite XI b6 to somite XIII a1. Common oviduct length nearly equal with length of vaginal duct. Vaginal sac slightly folded, reaching to somite XIV a1/a2–b5.

Description of holotype. Body firm, muscular, with constant width posteriorly, BL 19.7 mm, BW 3.7 mm ( Fig. 2 View Fig ). Caudal sucker ventral, elliptical, CL 4.3 mm, CW 2.57 mm; prehensile lobe undeveloped, not sharply hooked; with 57 friction rays ( Figs. 2B View Fig , 3F View Fig ).

Somite I completely merged with prostomium ( Fig. 3A View Fig ). Somite II uniannulate, comprising two paramedian ocular plates with one interocular plate and margins ( Fig. 3A View Fig ). Somite III uniannulate, comprising two ocular plates and two interocular plates with median small plates and margins ( Fig. 3A View Fig ). Somite IV uniannulate, comprising two ocular plates and four interocular plates with median small plate and margins ( Fig. 3A View Fig ). Somite V biannulate, (a1 + a2)> a3, (a1 + a2) comprising two ocular plates and six interocular plates ( Fig. 3A, B View Fig ). Somite VI dorsally triannulate/ventrally biannulate, a1 = a2 = a3/(a1 + a2)> a3. Somite V to somite VI (a1 + a2) unite altogether, forming posterior margin of oral sucker ( Fig. 3A–C View Fig ). Somite VII triannulate, a1 = a2 = a3 ( Fig. 3A–C View Fig ). Somites VIII–XXII quadrannulate, a1 = a2 = b5 = b6 ( Figs. 3D–F View Fig , 4A View Fig ). Somite XXIII triannulate, a1 = a2 = a3 ( Fig. 3D, E View Fig ). Somite XXIV biannulate, (a1 + a2) = a3 ( Fig. 3D, E View Fig ). Somites XXV–XXVII uniannulate; ambilateral margins of each of somites XXV–XXVII forming three lobes of one pair of trilobate respiratory auricles, median lobe of somite XXVI smaller than other two lobes ( Fig. 3D, E View Fig ). Anus at posterior margin of somite XXVII.

Male gonopore in somite XI b5/b6 ( Fig. 4A View Fig ). Female gonopore slightly anterior to middle of somite XII b5 ( Fig. 4A View Fig ). Gonopores separated by 3 + 1/2 annuli.

Anterior ganglionic mass in somite VII a1 and somite VIII a1. Ganglion VII in somite VIII a1 and a2. Ganglion VIII in b5 and b6. Ganglion IX in b5. Ganglia X and XI of each somite, in a2 and b5 ( Fig. 4B View Fig ). Ganglion XII in b5. Ganglia XIII–XV of each somite, in a2 and b5 ( Fig. 4B View Fig ). Ganglia XVI–XVIII of each somite, in a2 ( Fig. 4B View Fig ). Ganglia XIX and XX of each somite, in a2 and b5 ( Fig. 4B View Fig ). Ganglion XXI in somite XX b6 and somite XXI a1 ( Fig. 4B View Fig ). Ganglion XXII in somite XXI a2 and b5 ( Fig. 4B View Fig ). Ganglion XXIII in somite XXII a2 and b5 ( Fig. 4B View Fig ). Ganglion XXIV in somite XXIII a1 ( Fig. 4B View Fig ). Ganglion XXV in somite XXIII a2 ( Fig. 4B View Fig ). Ganglion XXVI in somite XXIII a2 and a3 ( Fig. 4B View Fig ). Posterior ganglionic mass in somite XXIII a3 to somite XXV ( Fig. 4B View Fig ).

Eyes 5 pairs, in parabolic arc; first pair on somite II, second pair on somite III, third pair on somite IV, fourth pair on somite V (a1 + a2), and fifth pair on somite VI a2 ( Fig. 3A, B View Fig ). Sensillae developed, one row on every annulus. Furrow pit undetectable.

Nephridiopores in 13 pairs, one each situated laterally at posterior margin of a1 of each somite in somites XI–XXIII ( Fig. 3E View Fig ). Nephridiopores anterior to somite XI undetectable. Nephridiopores of somite XXIV under respiratory auricles.

Each jaw without salivary papillae; monostichodont, number of teeth of each jaw uncounted. Pharynx reaching to somite VIII/somite IX. Crop reaching to somite XIX b6–somite XX a2, bearing 10 pairs of crop caeca: first pair in somite X b6 and somite XI a1; second pair in somite XI b5 and b6; third pair in somite XII a2–b6; fourth pair in somite XIII a2–b6; fifth pair in somite XIV a1–b5; sixth pair in somite XV a2–b6; seventh pair in somite XVI a1 and a2; eighth pair in somite XVII a1–b5; ninth pair in somite XVIII a2 and b5; and 10th pair being post-crop caeca, right post-crop caecum in somite XIX a1 to somite XXIV (a1 + a2), left post-crop caecum in somite XIX a1 to somite XXII b6. Intestine reaching to somite XXIII a1–somite XXIV (a1 + a2). Rectum simple, tubular.

Testisacs nine pairs with an additional sac on left side: first pair, right testisac in somite XIII b6 and somite XIV a1, left testisac in somite XIV a1; second pair, right sac in somite XIV b6 and somite XV a1, left sac in somite XV a1 and a2; third pair in somite XV b5 to somite XVI a1; fourth pair in somite XVI b5 and b6; fifth pair, right sac in somite XVII b5 to somite XVIII a1, left sac in somite XVII a2–b6; sixth pair, right sac in somite XVIII b5 to somite XIX a1, left sac in somite XVIII b5 and b6; seventh pair in somite XIX a2–b6; eighth pair, right sac in somite XX b5 to somite XXI a1, left sac in somite XX a2–b6; ninth pair, right sac in somite XXI a1–b5, left sac in somite XX b6 to somite XXI a2; and an additional testisac on left side in somite XXI b6 to somite XXII a2 ( Fig. 4B View Fig ). Paired epididymides developed; right epididymis in somite XIII b6 to somite XV a1; and left epididymis in somite XIV a1 to somite XV a2; from each epididymal mass, thick sperm ducts reaching to each ejaculatory bulb ( Fig. 4B–D View Fig ). Ejaculatory bulbs developed, ellipsoidal; right bulb in somite XI b6 to somite XII b5; and left bulb in somite XI b6 to somite XII a2 ( Fig. 4B–D View Fig ). Ejaculatory ducts narrow, running inward toward male atrium in somite XI b5; left ejaculatory duct crossing ventrally beneath nerve cord ( Fig. 4C, D View Fig ). Male atrium globular in somite XI b5 and b6 ( Fig. 4B–D View Fig ).

Paired ovisacs globular, in somite XII b5 to somite XIII a1 ( Fig. 4B, E, F View Fig ). Oviducts short; left oviduct crossing ventrally beneath nerve cord; both oviducts converging into common oviduct in somite XII b6 ( Fig. 4E, F View Fig ). Common oviduct descending to female vaginal sac in somite XII b6 to somite XIII a1/a2 ( Fig. 4E, F View Fig ). Vaginal sac slightly folded, reaching to somite XIV a1/a2 ( Fig. 4B, E, F View Fig ). Vaginal duct from somite XIII a2 to somite XII b5, directly descending to female gonopore ( Fig. 4E, F View Fig ).

Variation. BL 8.5 mm, BW 2.7 mm, CL 2.8 mm, CW 2.6 mm. Somite III uniannulate, comprising two ocular plates and three interocular plates with median small plates and margins. Somite IV uninnaulte, comprising two ocular plates and five interocular plates with margins. Somite V biannulate, (a1 + a2) = a3, (a1 + a2) comprising two ocular plates and eight interocular plates. Nephridiopores in somites IX and X detected. Male gonopore in somite XI b5/b6. Female gonopore in anterior margin of somite XII b5. Gonopores separated by 3 annuli at least. Paired epididymides; right epididymis in somite XIV b5 to somite XVI a1; and left epididymis in somite XIV b6 to somite XVI a2. Ejaculatory bulbs; right bulb in somite XII a2–b5; and left bulb in somite XII a2 to somite XIII a1. Paired ovisacs; right ovisac in somite XII b5 to somite XIII a1; left ovisac somite XII b5 and b6. Oviducts; right oviduct crossing ventrally beneath nerve cord. Common oviduct descending to female vaginal sac in somite XII b6 to somite XIII b6. Vaginal sac slightly folded, reaching to somite XIV b5. Vaginal duct from somite XIII b6 to somite XII b5.

Colouration. In life, dorsal surface yellowish clay with three brown longitudinal stripes with blackish borders; median stripe wider than lateral stripes, with irregular asymmetrical loops expanding toward lateral stripes ( Fig. 5 View Fig ); ventral surface paler than dorsal surface. Color faded in preservative, but longitudinal stripes with blackish borders on dorsal surface remain.

Distribution. Known only from the type locality and Ta Co, Son La Province in northern Vietnam ( Fig. 1 View Fig ). The elevations of the localities were more than 700 m above sea level. The individual from Doi Phuka was found on soil around a decayed banana tree containing very high moisture.

Natural history. The hosts are not known because the specimens examined were collected free-living, but are presumed to include amphibians ( Lai & Chen, 2010). The Vietnamese individual was collected when it was climbing the third author; therefore, mammals may also be hosts of T. longiducta .

Etymology. The specific name is a compound adjective derived from the Latin words, longus (long), and ductus (duct), referring to the fact that the common oviduct of this species nearly equals the length of its vaginal duct, a diagnostic character of the species.