Placobdella appalachiensis Moser & Hopkins

Hopkins, William A., Moser, William E., Garst, David W., Richardson, Dennis J., Hammond, Charlotte I. & Lazo-Wasem, Eric A., 2014, Morphological and molecular characterization of a new species of leech (Glossiphoniidae, Hirudinida): Implications for the health of its imperiled amphibian host (Cryptobranchus alleganiensis), ZooKeys 378, pp. 83-101 : 89-92

Placobdella appalachiensis Moser & Hopkins sp. n. Figs 2-4

Material examined.

Holotype (USNM 1232924) South Fork Holston River, Smyth County, Virginia.

Paratypes (USNM 1232925 - 1232942; YPM IZ 067799) South Fork Holston River, Smyth County, Virginia.

Morphological description.

External morphology. Body very deeply to deeply ovoid and triannulate. Length of preserved specimens 2.5 - 10.4 mm long, mean + SE 5.2 + 0.4 mm (n = 23), width at widest point (in posterior half of body) 2.0 - 5.9 mm, mean + SE 3.4 + 0.2 mm (n = 23). Dorsum chocolate (#7B3F00) to russet (#80461B) brown with 6 rows of papillae (2 para-medial, 2 para-lateral, & 2 lateral) and many, thin, unpigmented, vertical lines (Figure 2; see hex color codes http://www.colorhexa.com). Para-medial, para-lateral, and lateral papillar rows begin at two points (just lateral to the anus) and the papillae are on the neural annulus. Apical cephalic region unpigmented, extending and tapering posteriorly through one thin nuchal band. Two pairs of eye spots (one pair much larger than the other) within cephalic unpigmented region, and occasionally separated by a little less than the diameter of the larger eyespot. Anal region and small genital bar unpigmented to diffusely pigmented with scattered unpigmented to diffusely pigmented small patches in between. Caudal sucker, 0.5 - 2.1 mm in diameter, mean + SE, 1.2 + 0.1 (n = 18), generally unpigmented with a few brown chromatophores and without papillae. Ventrum unpigmented with very sparse scattering of a few brown/green chromatophores (Fig. 3). Male and female gonopores in furrows and separated by 2 annuli.

Internal morphology.

Digestive system: Proboscis posteriad of the rim/lip of the oral sucker. Short, blunt-tipped proboscis, uniformly cylindrical, and in membranous sheath. Salivary cells scattered in the anterior third of the body (diffuse salivary glands) and slightly more abundant near the base of the proboscis. Salivary ductule bundles join with retractor muscles and attach at each side of the base of the proboscis. Flaccid esophagus extends from the base of the proboscis with one pair of saccular mycetomes. Seven pair of diverticulated crop ceca and the last pair extending posteriad into four sections and diverticulated. Four pair of simple, saccular intestinal ceca. Simple rectum opening to anus, located one annulus anteriad of the caudal sucker.

Reproductive system: (Male) Male gonophores slightly raised. Male atrium opening into ovoid or elloptoid atrial cornue extending laterally and anteriorly from male gonopore into robust, coiled, muscular ejaculatory ducts, recurving posteriorly to robust seminal vesicles and narrow vas deferentia connecting to testisacs. Six pairs of orbicular testisacs, each testisac located in the space between pair of crop ceca. (Female) Female gonopore simple, opening to pair of bifurcated ovisacs. Ovisac length depends on the reproductive condition of the leech.

Taxonomic summary.

Type host: Eastern Hellbender, Cryptobranchus alleganiensis alleganiensis (Daudin, 1803).

Type locality.

South Fork Holston River, Smyth County, Virginia.

Type material.

USNM 1232924 (Holotype), USNM 1232925 - 1232942 (Paratypes), YPM IZ 067799 (Paratype).

Etymology.

Named for the Appalachian Region, where the leech is known to occur.

Molecular description.

DNA Analysis.

Molecular comparison of 637 nucleotides of CO-I revealed differences of 0.2% to 1.3% (1-8 nucleotides) among four specimens of Placobdella appalachiensis sp. n. (GenBank KF990590-KF990593) collected from South Fork Holston River, Smyth County, Virginia. Differences of 17.7% to 19.1% (113 to 122 nucleotides) were found between four specimens of Placobdella appalachiensis sp. n. and seven specimens of Placobdella cryptobranchii (GenBank KF601755-KF601761) collected from Missouri. CO-I sequence data among four specimens of Placobdella appalachiensis sp. n. revealed differences of 18.7% to 19.6% (119 to 125 nucleotides) compared to five specimens of Placobdella ornata (GenBank JQ8128-JQ8132) collected from the type locality (West River, New Haven County, Connecticut), differences of 18.8% to 20.0% (120-127 nucleotides) compared to four specimens of Placobdella ornata collected from the type locality (Shivericks Pond, Falmouth, Barnstable County, Massachusetts) of Placobdella phalera (junior synonym of Placobdella ornata ) (GenBank JQ812133-JQ812136), differences of 17.7% to 18.7% (113-119 nucleotides) compared to two specimens of Placobdella translucens (GenBank AY047328, JX122778), differences of 15.8% to 16.8% (101-107 nucleotides) from 1 specimen of Placobdella picta (GenBank AF116020), differences of 17.2% to 18.1% (110-115 nucleotides) from 1 specimen of Placobdella biannulata (GenBank AF116021), and differences of 17.9% to 19.0% (114-121 nucleotides) from 2 specimens of Placobdella sophieae (GenBank KF990594-KF990595) collected from Oregon.