Orobdella meisai, Nakano & Lai, 2017

Nakano, Takafumi & Lai, Yi-Te, 2017, A New Quadrannulate Species of Orobdella (Hirudinida: Arhynchobdellida: Orobdellidae) from Pingtung, Taiwan, Species Diversity 22, pp. 143-150 : 144-149

publication ID	https://doi.org/ 10.12782/sd.22_143
publication LSID	lsid:zoobank.org:pub:90220F49-CD28-47AB-A627-9C4C8682F50E
persistent identifier	https://treatment.plazi.org/id/E606D8B1-1A67-4C16-B045-F5C953A515C0
taxon LSID	lsid:zoobank.org:act:E606D8B1-1A67-4C16-B045-F5C953A515C0
treatment provided by	Felipe
scientific name	Orobdella meisai
status	sp. nov.

Treatment

Orobdella meisai sp. nov.

( Figs 2–4 View Fig View Fig View Fig )

Diagnosis. Body length of mature individual exceeding 6 cm. Somite IV uniannulate, somites VIII–XXV quadrannulate. Clitellum in somite XI b5 to somite XIII a2. Male gonopore in somite XI b5/b6, female gonopore slightly posterior to anterior margin of somite XIII a1, behind gastropore, gonopores separated by 5+1/4 annuli. Pharynx reaching to somite XV b5–b6. Gastropore conspicuous, slightly posterior to anterior margin of somite XIII a1. Gastroporal duct rudimentary tubular. Paired vasa deferentia thick. Epididymis lacking. Pre-atrial loop present. Atrial cornu lacking.

Material examined. Holotype: KUZ Z1917 View Materials , dissect- ed, collected from under a stone along the Jinshui Ying Old Trail , Fanliao, Pingtung County, Taiwan (22.40730°N, 120.758568°E; elev. 1470 m) by Takafumi Nakano ( TN) on 9 March 2017 GoogleMaps . Paratypes (12 specimens collected from around the type locality): KUZ Z1908 View Materials (22.407°N, 120.756°E; elev. 1490 m) by Wei-Ren Liang on 26 August 2014; KUZ Z1909 View Materials – Z1910 View Materials (22.407°N, 120.756°E; elev. 1490m) by Fu-Sheng Huang on 23 February 2014; KUZ Z1911 View Materials – Z1912 View Materials (22.40824°N, 120.75264°E; elev. 1650 m), KUZ Z1914 View Materials – Z1915 View Materials (22.40790°N, 120.75304°E; elev. 1620m) by Yi-Te Lai (YL) on 9 March 2017; KUZ Z1913 View Materials (22.40809°N, 120.75288°E; elev. 1620 m), KUZ Z1916 View Materials (22.40772°N, 120.75662°E; elev. 1450m) by TN on 9 March 2017; KUZ Z1918 View Materials – Z1919 View Materials (22.407933°N, 120.756530°E) by YL on 22 January 2017; and KUZ Z1920 View Materials (22.409192°N, 120.754820°E) by Kao-Shr Shiang on 9 December 2016 ( KUZ Z1910 View Materials , Z1914 View Materials , and Z1915 were dissected) GoogleMaps .

Description. Body firm and muscular, elongate, with constant width in caudal direction, dorsoventrally compressed, BL 62.5 mm, BW 4.7mm ( Fig. 2A, B View Fig ). Caudal sucker ventral, slightly elliptic, CL 2.7 mm, CW 2.9 mm ( Figs 2B View Fig , 3D View Fig ).

Somite I completely merged with prostomium ( Fig. 3A View Fig ). Somites II (=peristomium), III and IV uniannulate ( Fig. 3A View Fig ); somite II not separated from somite I. Somite V biannulate, (a1+a2)=a3; a3 forming posterior margin of oral sucker ( Fig. 3A, B View Fig ). Somites VI and VII triannulate, a1=a2=a3 ( Fig. 3A, B View Fig ). Somites VIII–XXV quadrannulate, a1=a2=b5=b6 ( Fig. 3A–E View Fig ). Somite XXVI triannulate, a1>a2<a3; a3 being ventrally last complete annulus ( Fig. 3C, D View Fig ). Somite XXVII uniannulate with slight dorsolateral furrow on respective sides ( Fig. 3C View Fig ). Anus behind somite XXVII; post-anal annulus absent ( Fig. 3C View Fig ).

Somite X b5 and somite XIII a2, respectively, being first and last annuli of clitellum ( Fig. 3E View Fig ).

Male gonopore in somite XI b5/b6 ( Fig. 3E View Fig ). Female gonopore slightly posterior to anterior margin of somite XIII a1, inconspicuous, located posterior to gastropore ( Fig. 3E, F View Fig ). Gonopores separated by 5+1/4 annuli ( Fig. 3E View Fig ).

Anterior ganglionic mass in somite VI a2 and a3. Ganglion VII in a1 and a2. Ganglia VIII–XIX, of each somite, in a2 ( Fig. 4B View Fig ). Ganglia XX–XXII, of each somite, in a1 and a2. Ganglion XXIII in a2. Ganglia XXIV–XXV, of each somite, in a1 and a2. Ganglion XXVI in somite XXV b6. Posterior ganglionic mass in somite XXVI a2 and a3.

Eyes in 3 pairs, 1st pair dorsally on anterior margin of somite III, 2nd and 3rd pairs dorsolaterally on posterior margin of somite V (a1+a2) ( Fig. 3A View Fig ). Papillae numerous, minute, hardly visible, on row on every annulus.

Nephridiopores in 17 pairs, each situated ventrally at posterior margin of a1 of each somite in somites VIII–XXIV ( Fig. 3B, D, E View Fig ).

Pharynx agnathous, euthylaematous, reaching to somite XV b5 ( Fig. 4A View Fig ). Crop tubular, acecate, reaching to somite XXI a2. Gastropore conspicuous, ventral, slightly posterior to anterior margin of somite XIII a1 ( Fig. 3E, F View Fig ). Gastroporal duct rudimentary tubular, reaching to somite XV a1/a2 ( Fig. 4A View Fig ); its pore opening to crop hardly detectable. Intestine tubular, acecate, reaching to somite XXIV a1/a2. Rectum tubular, thin-walled, straight.

Testisacs multiple ( Fig. 4B View Fig ); on right side, in somite XVIII a2 to somite XXV a2, in total ~40 testisacs, 4 in XVIII, 5 in XIX, 6 in XX, 6 in XXI, 5 in XXII, 5 in XXIII, 6 in XXIV, 3 in XXV; on left side, in somite XVIII a2 to somite XXIV

b6, in total ~35 testisacs, 3 in XVIII, 4 in XIX, 7 in XX, 5 in XXI, 5 in XXII, 5 in XXIII, 6 in XXIV. Paired vasa deferentia thick ( Fig. 4B View Fig ). Epididymis absent. Paired ejaculatory ducts in somite XI a2 to somite XVIII a1 ( Fig. 4B View Fig ); coiled in position posterior to ovisacs; each duct crossing ventrally beneath each ovisac, then coiled in position anterior to ovisacs; each winding from respective junction with vas deferens, narrowing toward atrium with pre-atrial loop extending to middle of somite XI a2. Atrial cornu absent. Atrium small, globular, in somite XI b5 and b6 ( Fig. 4B, C View Fig ). Penis sheath and penis absent.

Paired ovisacs globular, in somite XIII a2 and b5 ( Fig. 4B, D View Fig ). Oviducts thin-walled ( Fig. 4D View Fig ); both oviducts converging in to common oviduct in somite XIII a1; dorsal surface of junction of both oviducts covered with ventral nerve cord. Common oviduct thin-walled, short, directly descending to female gonopore ( Fig. 4D View Fig ).

Variation. Measurements (mean±1SD, followed by ranges in parentheses; n =13, including holotype): BL 48.9± 16.3 mm (27.4–73.1 mm), BW 4.2± 1.5 mm (2.1– 7.2 mm), CL 2.1± 0.68 mm (1.2–3.0 mm), CW 2.5± 0.79 mm (1.4–4.2 mm). Somite XXVI a3 sometimes with slight dorsal furrow, or dorsolateral furrow on respective sides. Somite XXVII generally uniannulate without secondary furrow, or rarely biannulate. First pair of eyes rarely dorsally on posterior margin of somite II, or on somites II/III; small unpaired eye dorsally on left posterior margin of somite III (KUZ Z1912). Pharynx reaching to somite XV b5/b6–b6. Crop reaching to somite XXI a1–a2. Gastroporal duct reaching to somite XV a2–b5/b6. Intestine reaching to somite XXIII b5/ b6–somite XXIV a2/b5. Testisacs; right side, ~34–42 sacs in somite XVII b5–b6 to somite XXV a1–a2; left side, ~36–42 sacs in somite XVII b5–b6 to somite XXIV b6–somite XXV a2. Paired ejaculatory ducts in somite XI a2 to somite XVII a2/b5–b5. Paired ovisacs in somite XIII a2, or in somite XIII a2 and b5.

Coloration. In life, dorsal-to-lateral surface yellowish brown with irregular brownish markings without distinct pattern ( Fig. 2C View Fig ); ventral surface brownish white with irregular dark markings, ventral median region rarely with markings. Color faded in preservative, but irregular markings on surface remain ( Fig. 2A, B View Fig ).

Distribution. This species was collected only from its type locality. The present locality is the southernmost habitat within the known range of Orobdella species.

Natural history. This species was found curled up under rocks in moist mountainous habitats, and is thus terrestrial. A mature individual bearing a slight clitellum (= holotype) was collected on 9 March 2017. This finding suggests that the reproductive season of this species begins in early-to-middle March.

Molecular analyses results. The ML tree (ln L = −28606.84; Fig. 5 View Fig ) for estimating the phylogenetic position of the new species had an identical topology to that of the BI tree (mean ln L =−28193.30; not shown). Orobdella meisai belonged to a well-supported clade (BS=100%, PP=1.0) containing the other eight species inhabiting the western part of Honshu to Taiwan. The clade was divided into two subclades: a well-supported lineage (BS=99%, PP=1.0) consisted of four species, i.e., O. esulcata Nakano, 2010 , O. naraharaetmagarum Nakano, 2016 , O. kanaekoikeae Nakano, 2017 and O. brachyepididymis Nakano, 2016 , inhabiting the western part of Honshu, Shikoku and Kyushu islands of Japan; another lineage was not fully supported in the ML tree (BS=49%, PP=0.92), comprising three species, i.e., O. mononoke Nakano, 2012 , O. shimadae Nakano, 2011 and O. dolichopharynx Nakano, 2011 , from the Ryukyu Islands, and the two Taiwanese O. ketagalan and O. meisai . The monophyly of O. shimadae , O. dolichopharynx , O. ketagalan and O. meisai was supported (BS=83%, PP=1.0). The two Ryukyu species, O. shimadae inhabiting Okinawajima island, and O. dolichopharynx known from Amamioshima island, formed a fully supported clade (BS=100%, PP=1.0). Monophyly of the Taiwanese O. ketagalan and O. meisai was also well-supported (BS=92%, PP=1.0).

The ND1 sequences ( LC314421 View Materials and LC314426 View Materials ) obtained from the holotype and paratype of O . meisai exhibit unique genetic variations compared with those of the other known Orobdella leeches. The ND1 sequences of O. meisai lack 97th–111th and 249th–260th bp positions in those of the other congeners. Since those missing positions are counted from the first position of the ND1 sequences, the former deletion indicates that the 33rd–37th codons are missing from the O. meisai ND 1 sequences, and the latter deletion shows that the 83rd–87th codons are compacted into a single DNA triplet.

Etymology. The specific name is from a Japanese word meisai (=camouflage) referring to the dorsal coloration of the new species. The specific name is thus treated as indeclinable.

Remarks. Orobdella meisai clearly belongs to Orobdella , because it possesses the generic diagnostic characteristics defined by Nakano (2016a): post-anal annulus absent; male gonopore in posterior part of somite XI; female gonopore in anterior part of somite XIII; gonopores separated by more than one full somite; pharynx agnathous euthylaematous; gastropore in anterior part of somite XIII; gastroporal duct lying on female organ; testisacs multiple; male atrium in posterior part of somite XI, without penis sheath or penis; ovisacs globular in somite XIII; female median reproductive system essentially lacking.

According to taxonomic studies ( Nakano 2010, 2011b, 2012a; Nakano and Lai 2012; Nakano 2014; Nakano and Seo 2014; Nakano 2016a, b, 2017b), the new species is distinguishable from the ten quadrannulate species ( O. brachyepididymis , O. esulcata , O. kanaekoikeae , O. kawakatsuorum Richardson, 1975 , O. ketagalan , O. koikei Nakano, 2012 , O. masaakikuroiwai Nakano, 2014 , O. naraharaetmagarum , O. tsushimensis , and O. whitmani Oka, 1895 ) by the following combination of characters ( Table 2): body length, annulation of somites IV and XXV, number of annuli between gonopores, pharynx length, gastroporal duct, epididymidal lengths and atrial cornua. Orobdella meisai can clearly differ from these known quadrannulate species in having 5+1/4 annuli between the gonopores, the pharynx reaching to the posterior part of somite XV, the rudimentary tubular gastroporal duct, and in lacking atrial cornua in the male median reproductive system.