Placobdella siddalli Richardson & Moser

Richardson, Dennis J., Moser, William E., Hammond, Charlotte I., Lazo-Wasem, Eric A., McAllister, Chris T. & Pulis, Eric E., 2017, A new species of leech of the genus Placobdella (Hirudinida, Glossiphoniidae) from the American alligator (Alligatormississippiensis) in Mississippi, USA, ZooKeys 667, pp. 39-49 : 40-44

Placobdella siddalli Richardson & Moser sp. n. Figures 1, 2, 3; 5, 6

Material examined.

Holotype (YPM 083857) Davis Eddy, a cypress swam constituting an oxbow lake of the Pascagoula River in the Pascagoula River Wildlife Management Area, George County, Mississippi (30°54'11"N, 088°44'35"W).

Paratypes (YPM 083875-083876, YPM 090164-090165; USNM 1422202-1422203) Davis Eddy, a cypress swam constituting an oxbow lake of the Pascagoula River in the Pascagoula River Wildlife Management Area, George County, Mississippi (30°54'11"N, 088°44'35"W).

Morphological description.

External morphology: (Fig. 1) Body elliptoid; length of preserved specimens 9.0-11.1 (9.8) mm, width at widest point (in center of body) 3.6-5.0 (4.5) mm. Dorsum base color beige with olive-green pigment spots. Dorsal papillae arranged in five rows (dorsomedial, two paramedial and two paralateral rows of unpigmented, stellate papillae) with repeating patterns of papillae size as follows: dorsomedial papillus of neural annulus large; paramedial papillae of neural annulus small; paralateral papillae of neural annulus large. Dorsomedial papillus of annulus posterior to neural annulus small; paramedial papillae of annulus posterior to neural annulus large; paralaterial papillae of annulus posterior to neural annulus small. Dorsomedial papillus of annulus anterior to neural annulus greatly reduced (sensillus); paramedial and paralateral papillae lacking on annulus anterior to neural annulus. Lateral papillae much less organized, not in distinct rows. Lateral region with alternating unpigmented and modestly pigmented sections (being characterized by small chromatophores). Anal opening located in furrow, one anteriad annulus from the caudal sucker. Beginning adjacent to the anus and commencing anteriad are two rows of three papillae, followed by two pairs of prominent paramedial papillae. Two pair of near-coalesced eyespots, typical of the genus Placobdella , within lateral unpigmented mask that extends posteriad into interrupted dorsal-medial pigment line that extends posteriorly to anus. Most pronounced pigmentation of dorsal-medial pigment line from genital region to anterior pair of prominent paramedial papillae. Caudal sucker orbicular, diameter 2.0-2.2 (2.1) mm; 18.64-22.9 (21.1) % of the length leech; dorsal surface with approximately three rows of papillae, the anterior-most of which is most prominent. Ventral surface of the whole body with scattered chromatophores, most concentrated in genital region and without stripes.

Internal morphology: (Figs 2 and 3) Proboscis pore on rim/lip of anterior sucker. Blunt-tipped muscular proboscis nearly uniformly cylindrical, only very modest enlargement at base. Two pair of discrete salivary glands. Anterior pair very narrowly doliform to oblong and slightly enlarged anteriad; ductal medially inserted into narrowly elliotoid posterior salivary glands; ductal of anterior salivary gland anastomoses with ductual of posterior salivary gland half-way between the posterior salivary gland and proboscis forming common duct. Esophagus extends from the base of the proboscis with one pair sac-like mycetomes. Seven pairs of diverticulated crop ceca, last pair extending posteriorly and diverticulated into four sections. Four pairs of intestinal ceca.

Reproductive system: Male and female gonopores in furrows and separated by two annuli. Six pair of testisacs.

Taxonomic summary.

Type host. American Alligator , Alligator mississippiensis (Daudin, 1802) Cuvier, 1807

Type locality.

Davis Eddy, a cypress swamp constituting an oxbow lake of the Pascagoula River in the Pascagoula River Wildlife Management Area, George County, Mississippi (30°54'11"N, 088°44'35"W).

Type material.

YPM 083857 (Holotype), YPM 083875-083876, YPM 090164-090165 (Paratypes), USNM 1422202-1422203 (Paratypes).

Etymology.

The specific epithet siddalli is in honor of Dr. Mark Siddall in recognition of the profound advancements that he has contributed to our understanding of glossiphoniid leeches, particularly in regard to the taxonomic importance of preanal papillae.

Molecular description.

Molecular characterization is based on sequence of 626 nucleotides of the mitochondrial Cytochrome c oxidase subunit I (GenBank KY780962). Molecular comparison of 626 nucleotides of CO-I revealed 100% identify between two specimens of Placobdella siddalli Richardson & Moser collected from the same host in Davis Eddy, George County, Mississippi (type locality; YPM 083876, GenBank KY780962 and an interspecific difference of 14.0% to 15.7% (88 to 98 nucleotides) between P. siddalli Richardson & Moser and four specimens of P. multilineata from Louisiana, Mississippi, and Oklahoma. Additional intraspecific differences of 15.9% to 16.7% (99 to 105 nucleotides) were found between P. siddalli Richardson & Moser and four specimens of P. rugosa collected from the type locality (North Dakota; GenBank JX412986-JX412990); difference of 18.0% (113 nucleotides) between P. siddalli Richardson & Moser and three specimens of P. ali from the type locality (New York) and Connecticut (GenBank HM347040-HM347042); differences of 16.9% to 17.3% (106 to 109 nucleotides) between P. siddalli Richardson & Moser and five specimens of P. papillifera (GenBank KC505241-KC505245) from its type locality (West River, New Haven, New Haven County, Connecticut); differences of 15.0% to 15.3% (94 to 96 nucleotides) between P. siddalli Richardson & Moser and five specimens of P. ornata (GenBank JQ812128-JQ812132) collected from the type locality (West River, New Haven County, Connecticut); and differences of 14.7% and 14.8% (92 to 93 nucleotides) between P. siddalli Richardson & Moser and five specimens of P. parasitica collected from the type locality (Minnesota; GenBank KF058895-KF058899).