Tritetrabdella taiwana (Oka, 1910)

Lai, Yi-Te, Nakano, Takafumi & Chen, Jiun-Hong, 2011, Three species of land leeches from Taiwan, Haemadipsa rjukjuana comb. n., a new record for Haemadipsa picta Moore, and an updated description of Tritetrabdella taiwana (Oka), ZooKeys 139, pp. 1-22 : 12-15

Tritetrabdella taiwana (Oka, 1910)

Haemadipsa japonica var. taiwana Oka, 1910. Annot. Zool. Jap. 7: 165-183

Haemadipsa zeylanica Takahashi, 1934. Rep. Jpn. Sci. Assoc. 10: 744-749

Haemadipsa japonica var. taiwana Keegan et al., 1968. Biomed. Rep. 406 Med. Lab. No. 16. United States Army Medical Commend, Japan.

Haemadipsa japonica var. taiwana Wu, 1979. Quart. J. Taiwan Mus. 32: 193-207

Tritetrabdella taiwana Sawyer, 1986. Leech Biol. Behav. Clarendon Press, Oxford, United Kindom.

Haemadipsa japonica Yang, 1996. Fauna Sinica, Annelida : Hirudinea. Science Press, Beijing, China.

Tritetrabdella taiwana Lai and Chen, 2005. Note Newsl. Wildlifers 9: 10-14

Tritetrabdella taiwana Lai et al., 2009. Zootaxa 2068: 27-46

Material examined.

L00084 collected at 9th Jun. 2002 in Wulai Town, Taipei County; L00085 collected at 11th Oct. 2003 in Nantou County; L00086 & L00087 collected at 1st Jun. 2004 in Taipei Zoo, Taipei City; and L00109 collected at 15th Feb. 2007 in Taipei City.

Diagnosis.

This species can be recognized by the yellowish dorsum with three dark or black bordered brown stripes, in which the supramarginal pair is simple, and the mid-dorsal one has a few irregular, asymmetrical, elongated circles or loops that extend laterally between two stripes. These circles or loops are either connected the mid-dorsal and the supramarginal stripes, or are disconnected from the stripes to form isolated brown spots with a dark border between the two stripes (Fig. 3A). A mid-body somite with four annuli, rather than the usual five annuli of other land leech species in Taiwan, is also an easily recognized characteristic of this species.

External morphology.

Body length 12-25 mm, maximum body width 2-4 mm in relaxed specimens and 4-6 mm in specimens filled with blood; anterior sucker diameter 2.0-2.6 mm, posterior sucker diameter 3.0-4.5 mm. Body elongated, slenderly cylindrical, with dorsum depressed moderately from the end to the head; venter flat. Clitellum usually conspicuously wider and thicker. Head of dorsal anterior sucker with broadly rounded, less sub-triangular outline (Fig. 3B); venter of lip soft and finely granular, with no permanent furrows anteriorly but a median fissure posteriorly continuing forward the median velar sinus. Anterior sucker deep, wide, triangularly cupuliform with well-developed lateral buccal lobes and frill. On the sides and floor of the buccal chamber are four pairs of folds or lobes reaching to the membranous velum, through the triangular opening of which the three jaws are visible. Posterior sucker large, broadly ovate, slightly longer than wide, diameter larger than maximum body width, with a definite anterior median prominence but no sharply hooked papilla. Auricles obscure, small, white, and trilobate with the middle lobe smallest.

Dorsum strongly tessellated and areolated, with areas bearing semi-transparent tipped and inconspicuous sensillae on each somite. Venter tessellated less, nearly smooth. Dorsum of posterior sucker tessellated, with four or five irregular circles of polygonal areas. Venter of posterior sucker with rays 57 to 61, not extending into the center and leaving a depressed, faintly tessellated circular central area.

Dorsum yellowish, with three broad, dark or black bordered brown stripes, in which the supramarginal pair simple, and the mid-dorsal one with a few irregular, asymmetrical, elongated circles or loops extending laterally between two stripes. Sometimes these circles or loops either connect the mid-dorsal and the supramarginal stripes, or disconnected from stripes and become isolated brown spots with dark border between two stripes. These stripes differ in exact form and position on each individual. In long preserved specimens, however, color of brown stripes has faded, leaving only longitudinal irregular and asymmetrical black borders on the dorsum (Fig. 3A). Venter uniformly yellowish as the dorsum. Dorsum of posterior sucker yellowish; venter of posterior sucker yellowish, or paler than venter body.

Eyes five pairs, punctiform, large and conspicuous (especially the 1st and 2nd pairs), arranging respectively at II (2nd annulus), III (3rd annulus), IV (4th annulus), V (5th annulus) and VI (8th annulus) in parabolic arc (Fig. 3B).

Eighty-two annuli. I uniannulate, with two rows of areola in which the anterior row much smaller and like those of the ventral face of the lip. II and III uniannulate, with the interocular region being divided into two areas in III. IV uniannulate, with the interocular region being divided into four areas. V biannulate dorsally ((a1a2)>a3) with six interocular areas in the first annulus of this somite in dorsum; uniannulate ventrally as the buccal ring. VI triannulate dorsally (a2>a3>a1) and biannulate ventrally ((a1a2)>a3). VII triannulate (a1=a2<a3). VIII quadrannulate (a1=a2>b5=b6). IX–XXII midbody somite and quadrannulate, with the four annuli of the same length. XXIII triannulate (a1=a2>a3), with a1 & a2 partly united ventrally. XXIV triannulate with the three annuli of the same length. XXV biannulate ((a1a2)>a3), with annuli being divided into irregular polygonal areas, and each annulus bearing the first and second auricular lobes at the margins. XXVI uniannulate, being divided into irregular polygonal areas and with the third auricular lobe at the margins. XXVII uniannulate, being divided into irregular polygonal areas. Anus in XXVII (82nd annulus). Clitellum from X b5 (23rd annulus) to XIII a2 (34th annulus). Gonoporesseparated by three and a half annuli; male at XI b5/b6 (27th/28th annulus); female at XII b5 (31st annulus).

Internal morphology.

Jaws three, crescent shaped, small and very prominent, with about 45 teeth of the usual form and no salivary papillae. Pharynx in VII–IX, long and wide with spongy wall. Crop in X–XIX; with 10 pairs of caeca in each segment respectively; first nine pairs simple and unlobed, while the last pair of caeca in XIX elongated posteriorly toXXIV and lateral to intestine. Intestine in XIX–XXIV, without caeca,tapered sharply to rectum in XXIV. Rectum large and wide, tapered towards anus in XXVII.

Ten pairs of testisacs at XIII/ XIV–XXII /XXIII. Vas deferens enters epididymis in XV and XVI. Epididymis always posterior beyond the vaginal sac, located variably i n XV–XVII, in some cases from XIII to XIV with a long tail-like caudal part extending from XIV to XXVIII,; moderately to slightly massive, entangled with each other as a whole mass, and with the anterior part of the mass usually covering on or covered by the vaginal sac. Ejaculatory bulbs large, elongated ellipsoid, lying at about the same level lateral-posteriorly or even totally posteriorly to the atrium, and connected by thick and short ejaculatory ducts to atrium in XI. Atrium moderate or small sized, round, rising dorsad of the level of the nerve cord passing along in the right side. Prostate glands of a thick layer covered on the atrium, ejaculatory duct, and anterior part of the ejaculatory bulbs. Ovisacs in XII, with very short oviduct joined into a short, slender, and curled common oviduct. Vaginal sac located variably in XII–XV, elongated ovate, with a very short vaginal stalk extended ventro-anteriorly into female gonopore in XII (Fig. 3C).

Distribution.

This species is only recorded in East and South East Asia, including the Indo-Chinese Peninsula, Ryukyu Islands of Japan, and Taiwan. In Taiwan, this species is recorded in the moist forests of low- and middle-elevation mountains around the island. In our recent surveys, it was collected in Taipei, Nantou, Pingtung, Yilan, and Hualien (Fig. 4).

Habitat.

Commonly found on the ground in moist forests. It attaches to leaf litter, grasses, and bushes on the ground.

Host.

Amphibians and medium- or large-sized mammals. The amphibian is probably the primary host, as this species has been frequently recorded parasitizing frogs and toads in Taiwan, including the common toad Bufo bankorensis Barbour, the Taipei green tree frog Rhacophorus taipeianus Liang & Wang, the temple tree frog Chirixalus idiootocus Kuramato & Wang, Swinhoe’s frog Rana swinhoana Boulengeer, and the olive frog Rana adenopleura Boulengeer.

Remarks.

Although Oka (1910) recorded that Tritetrabdella taiwana causes a considerable amount of injury by taking blood meals in the nasopharyngeal region of mammals, such as dogs and humans, there is doubt about such parasitic behavior in this species. Oka (1910) mentioned that the leeches of this species enter the nostrils of dogs and men to feed on blood by fastening to the mucous membranes of the nasal passages. However, based on Keegan et al. (1968) and our direct observations of the movement and attaching ability of this species, we argue that the leeches recorded as parasitic in the nasal cavities of mammals may in fact be the nasal leech Dinobdella ferox (Blanchard), which is a notorious leech species that specifically parasitizes the nasopharyngeal region of mammal hosts for fast growth before maturation, rather than Tritetrabdella taiwana .

In addition, because Tritetrabdella taiwana was the only land leech species that has been recorded feeding on frog and toad hosts, sometimes even in groups, it is possible that this species mainly acquires blood from amphibian hosts, whereas mammals covered in body hair are not a primary diet choice. This suggestion may also explain that, while Tritetrabdella taiwana is as widely distributed as other land leech species in Taiwan, such as Haemadipsa rjukjuana , there are fewer records of Tritetrabdella taiwana attacking hikers.