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| Cambarus emegi Lieb, Williams, Foltz & Loughman, 2026 |
Abstract
A new species of crayfish, Cambarus emegi sp. nov., is described from the upper James and Roanoke River basins in Virginia and the lower Delaware River basin in Pennsylvania, where it occurs in streams and small rivers. The species was formerly part of the Cambarus acuminatus species complex (Cambarus species C complex), a long-standing taxonomic enigma that is widely distributed across the Atlantic slope drainages of eastern North America. Cambarus emegi sp. nov. can be distinguished from Cambarus acuminatus due to the absence of a well-defined subpalmar tubercle, greater number of punctations across its areola, and differences in the mesial process of the form I male gonopod. Coloration and pattern in life differ between the two species. Additionally, the distributions of C. emegi sp. nov. and C. acuminatus are separated by hundreds of kilometers. The ranges of two other undescribed members of the Cambarus species C complex border that of C. emegi sp. nov. in Virginia. These species do not appear to overlap geographically; C. emegi sp. nov. is confined to the Ridge and Valley physiographic province, whereas the two undescribed species are found in the Blue Ridge and northern inner Piedmont regions. Cambarus emegi sp. nov. is morphologically similar but visually and genetically different from the undescribed species directly to the south in the upper Roanoke River system. Cambarus emegi sp. nov. is both visually and morphologically similar but genetically distinct from the undescribed species immediately downstream in the James River basin. Cambarus emegi sp. nov. is threatened by several potentially interacting factors including invasive crayfishes, narrow range, and urban and agricultural development. Alarmingly, the species is being rapidly replaced by invasive Faxonius species across a substantial part of its range. This paper represents an important step in providing the information needed to conserve and manage Cambarus emegi sp. nov.
Crustacea, Cambarus species C., Cambarus acuminatus, new species, Ridge and Valley, Northern Piedmont, Delaware, James, Roanoke, invasive crayfish
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| Cambarus emegi sp. nov., color in life: (a) holotype, NCSM 95987; (b) allotype, NCSM 95988. |
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| Life color and color pattern of adult Cambarus emegi sp. nov.: (a) dorsal view; (b) oblique lateral view (photo credit Zackary A. Graham). |
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| Life color and color pattern of juvenile Cambarus emegi sp. nov. |
Cambarus emegi sp. nov.
Diagnosis.—Body and eyes pigmented. Rostrum weakly to moderately excavated and ventrally deflected anteriorly; rostral margins subparallel, pronounced and entire through acumen, and more thickened posteriorly than anteriorly; acumen acuminate with prominent dorsally deflected spiniform tubercle at terminus. Areola 2.2–3.6 (¯x=2.7, n=42, s=0.4) times as long as wide, with 6–10 (¯x=8.5, n=42, s= 0.7) punctations across narrowest point. Lateral portion of branchiostegal region of carapace heavily punctate; hepatic regions also punctate with welldeveloped tubercles. Strong cervical spines present; branchiostegal spine prominent; postorbital ridge terminating anteriorly in spiniform tubercle or spine. Weak to acute suborbital angle typically present, rarely absent; suborbital angle terminating anteriorly in spiniform tubercle or spine. Antennal basipodite spines prominent; ischiopodite spines present but not prominent.
Etymology.—Derived from the Turkish work “emeği” meaning “labor of” or “hard work of”, which seems appropriate given this project required many years and the collection of thousands of specimens from South Carolina to Pennsylvania. Additionally, the name honors Emily (Em) and Megan (Meg) Lieb, the senior author’s two daughters, who happily accompanied him on many crayfish sampling trips as children and later helped him collect C. emegi sp. nov. from sites in its Pennsylvania range.
Common name.—We propose Enigma Crayfish as the common name.
David A. LIEB, Bronwyn W. WILLIAMS, David A. FOLTZ II and Zachary J. LOUGHMAN. 2026. Description of A New Stream-dwelling Species of Cambarus (Decapoda: Cambaridae) from Virginia and Pennsylvania (USA) with Notes on its Distribution, Ecology, and Conservation Status. Zootaxa. 5857(2); 299-316. DOI: doi.org/10.11646/zootaxa.5857.2.5 [2026-07-29]
