identifier	taxonID	type	CVterm	format	language	title	description	additionalInformationURL	UsageTerms	rights	Owner	contributor	creator	bibliographicCitation
BEE87AD8F9855E58B85948C68465DFB9.text	BEE87AD8F9855E58B85948C68465DFB9.taxon	http://purl.org/dc/dcmitype/Text	http://rs.tdwg.org/ontology/voc/SPMInfoItems#GeneralDescription	text/html	en	Stygobromus paveki Cannizzaro, Sawicki & Niemiller 2026	<div><p>Stygobromus paveki Cannizzaro, Sawicki &amp; Niemiller sp. nov.</p><p>Figs 12, 13, 14, 15, 16, 17, 18</p><p>Type material.</p><p>Holotype: • female 6.80 mm, USA: Maryland, Prince George’s County, <a href="https://tb.plazi.org/GgServer/search?materialsCitation.longitude=-76.8347&amp;materialsCitation.latitude=39.066" title="Search Plazi for locations around (long -76.8347/lat 39.066)">Baltimore – Washington Parkway (southbound), near a Food Lion grocery store</a> (39.0660°N, 76.8347°W), deposited in the National Museum of Natural History, Smithsonian Institution, Washington, D. C., USA (USNM 1456550). Collected 28 November 2022 by Dave C Culver; Thalia Eigen; Elizabeth Sartain; Elizabeth Burch . Allotype: • male, 10.40 mm (USNM 1456551), same locality and date as holotype . Paratypes: • 1 paratype female same locality, and date as holotype (USNM 1456552); • 2 paratype females same locality as holotype, date collected 6 January 2023 (USNM 1456553, USNM 1456554) .</p><p>Etymology.</p><p>The species name is in honor of Dr. Diane Pavek, Research Coordinator and Threatened and Endangered Species Specialist, National Capital Region, National Park Service. Over several decades, Dr. Pavek has been steadfast in her support of research on and protection of the specialized fauna of seeps.</p><p>Type locality.</p><p>Hypotelminorheic seep along the Baltimore – Washington Parkway (southbound), near a Food Lion grocery store, Prince George’s County, Maryland, USA (Fig. 1; 39.0660°N, 76.8347°W). The site is approximately 50 m from the southbound lanes of the Parkway and lies within the Upper Patuxent River watershed.</p><p>Diagnosis.</p><p>Small stygomorphic species allied with the S. tenuis species group. Stygobromus paveki sp. nov. is distinguished from S. hayi and S. allegheniensis by uropod 1 bearing a robust seta along the inner margin and by an entire telson that narrows slightly distally. It differs from S. allegheniensis by the concave palmar margin of gnathopod 1 and by the slightly convex bases of pereopods 5–7, and from S. hayi by having fewer than 10 robust setae along the apical margin of the telson. It differs from S. tenuis tenuis by the absence of a coxal gill on pereopod 7 and by the absence of a sternal gill on male pleonite 1. It differs from S. tenuis potomacus by body size (largest male 10.4 mm; largest female 7.9 mm). It differs from S. anacostensis by lacking aesthetasc-like structures on the flagellum of antenna 2, by the male antenna 2 being proportionally shorter than antenna 1, and by the more setose anterior and posterior margins of the bases of pereopods 3 and 4. It differs from S. scottsruni by having a concave palmar margin on gnathopod 1 and by having a greater number of segments on the inner and outer rami of pleopods 1 and 3.</p><p>Stygobromus paveki sp. nov. can be further distinguished from all other members of the S. tenuis species group by the combination of: (1) bifurcate sternal gills; (2) telson lacking lateral spines; and (3) the posterodistal margin of the carpus of gnathopod 2 bearing rastellate seta (e).</p><p>Description.</p><p>Female: holotype, USNM 1456550 (TRS 386.8); Size 6.80 mm.</p><p>Antennae. Antenna 1 (Fig. 12 A): 40 % body length, 1.2 × length of antenna 2; primary flagellum with 20 segments, aesthetascs on most segments, aesthetascs shorter than respective segments; accessory flagellum 2 - segmented, reaching beyond first segment in length. Antenna 2 (Fig. 12 B): gland cone distinct; peduncle 1.4 × length of flagellum, with robust setae on dorsal margins of segments 3, 4, and 5; peduncle segment 4 subequal in length to segment 5; flagellum 12 - segmented, lacking robust setae.</p><p>Mouthparts (Figs 12 C, 12 D, 13 A – E). Mandibles: left mandible (Fig. 12 C) incisor 5 - dentate, lacinia mobilis 4 - dentate, with 6 robust serrate and numerous plumose accessory setae; molar process reduced with simple seta; palp with 3 segments, second segment subequal in length to third, with inner margin bearing 7 setae and sparse fine setae; segment 3 with 3 C-setae, 3 E-setae, 1 B-seta, and 8 D-setae, face with pubescent setae distally. Right Mandible (Fig. 12 D): incisor 4 - dentate, lacinia mobilis bifurcate, both lobes with numerous protuberances; accessory setae row with 5 robust, serrate setae and numerous plumose setae; molar process reduced with simple seta. Palp with 3 articles, relative articles length and setation patterns as in left mandible.</p><p>Upper Lip (Fig. 13 A): elongated, apical margin of labrum with numerous fine setae.</p><p>Lower Lip (Fig. 13 B): inner lobes distinct; outer margin of outer lobe sparsely covered in fine setae; inner margin of outer lobe heavily setose.</p><p>Maxilla 1 (Fig. 13 C): inner plate with 4 plumose marginal setae, pubescent setae covering inner margin; outer plate with 7 apical comb spines, pubescence covering inner margin; palp with 2 segments, distal segment weakly pubescent; subapical margin of distal article with 2 setae, apical margin with 6 setae.</p><p>Maxilla 2 (Fig. 13 D): both inner and outer plates covered in pubescent setae; outer plate not as wide as inner plate, with numerous distal setae; inner plate narrowing distally, with numerous apical setae and 3 large plumose facial setae.</p><p>Maxilliped (Fig. 13 E): inner plate shorter than outer plate, with 4 naked cuspidate setae, and 3 palmate robust setae along apical margin, surface of plate covered in fine pubescence; outer plate armed with numerous setae covering inner and apical margins; palp second segment with numerous marginal setae, third article with numerous marginal / submarginal setae; dactyl with 1 outer seta and 2 inner setae.</p><p>Gnathopods. Gnathopod 1 (Fig. 14 A): coxal plate with 4 apical setae; basis with long setae inserted along anterior, and posterior margins; ischium with 5 setae and pubescence along posterior margin; merus pubescent along posterior surface, numerous distal setae; carpus approximately 60 % length of propodus with robust seta along anterior margin and 2 setae on anterodistal margin, one of which is approximately 65 % length of propodus, posterior margin with single group of plumose setae and 7 submarginal setae directed distally; propodus approximately 1.25 × longer than broad, with 1 marginal anterior seta, 3 superior medial setae, 6 setae inserted at anterodistal corner, 4 inferior medial setae and numerous plumose posterior setae; palm oblique, weakly concave, with serrate blade-like edge running the length, 7 outer and 6 inner bifid robust setae, 11 outer setae, and inner seta; inner margin of defining angle with 4 bifid robust setae, outer margin with 6 bifid robust setae; dactylus with outer seta and 5 short setae covering the entire inner margin and seta placed along the inner margin at base of nail.</p><p>Gnathopod 2 (Fig. 14 B): coxal plate with 3 apical setae; basis with long setae inserted along anterior, and posterior margins; ischium with 4 setae and pubescence along posterior margin; merus with pubescence covering posterior surface and 6 posterodistal setae; carpus approximately 95 % length of propodus, with robust seta along anterior margin and two setae on anterodistal margin, one of which is approximately 50 % length of propodus, posterior margin with 6 groups of plumose setae, distal-most bearing 5 rastellate setae, and 5 submarginal setae directed distally; propodus 1.1 × longer than broad, with marginal anterior seta, 5 superior medial setae, 6 setae inserted at anterodistal corner, 4 inferior medial setae, proximal most paired, and 6 groups of plumose setae along posterior margin; palm weakly transverse, weakly concave, with serrate blade-like edge running the length, 4 outer and 5 inner bifid robust setae, 5 outer setae, with inner seta; defining angle with 5 outer and 6 inner bifid robust setae; dactylus with outer seta and 4 short setae covering the entire inner margin and 3 setae placed along the inner margin at base of nail.</p><p>Pereopods. Pereopod 3 (Fig. 15 A): coxal plate with 7 apical setae; basis with numerous long setae placed along both anterior and posterior margins; merus 1.5 × longer than carpus, carpus approximately 80 % of propodus in length; dactylus approximately 40 % length of propodus, with plumose seta on anterior margin, seta placed along posterior margin followed by thin seta on medial margin.</p><p>Pereopod 4 (Fig. 15 B): coxal plate armed with 7 apical setae; basis with numerous long setae placed along both anterior and posterior margins; subequal to pereopod 3 in length; merus approximately 1.2 × longer than carpus; carpus subequal in length to propodus; dactylus approximately 30 % length of propodus, setation as in pereopod 3.</p><p>Pereopod 5 (Fig. 15 C): coxal plate large, bilobate with distinct anterior and posterior lobes, posterior lobe with 3 setae on distal corner; basis posterior margin weakly convex with 11 shallow serrations, anterior margin with 6 split-tipped robust setae and 2 distal split-tipped setae; merus subequal in length to carpus; carpus subequal to propodus; dactylus approximately 25 % length of propodus, with plumose seta on posterior margin, seta placed along anterior margin, followed by thin seta on medial margin.</p><p>Pereopod 6 (Fig. 15 D): coxal plate bilobate, with weakly produced anterior lobe, posterior lobe bearing 2 robust and 2 simple apical setae; basis posterior weakly convex with 11 weak serrations, anterior margin with 7 split-tipped robust setae, and 2 robust setae at anterodistal corner; merus subequal in length to carpus; carpus subequal in length to propodus; dactylus approximately 25 % length of propodus, setation as in pereopod 5.</p><p>Pereopod 7 (Fig. 15 E): coxal plate small, subtriangular, with 3 posterior setae; basis posterior margin weakly convex with 14 weak serrations and convex distal corner, anterior margin with 7 split-tipped robust setae, and 2 robust setae at anterodistal corner; merus subequal in length to carpus; carpus subequal in length to propodus, dactylus approximately 25 % length of propodus, setation as in pereopods 5, 6.</p><p>Gills and broodplates (Figs 14 B, 15 D 1, E 1). coxal gills on somites 2–6, somites 6 and 7 with bifurcate sternal gills. Brood plates ovate, setaceous, present on somites 2–5, decreasing in size posteriorly.</p><p>Pleon. Epimera (Fig. 16 A): first epimeron ventral margin with 2 robust setae, distoposterior corner rounded, posterior margin with 2 setae placed near distoposterior corner. Second epimeron ventral margin with 4 robust setae, distoposterior corner rounded, posterior margin with 3 setae. Third epimeron ventral margin with 4 robust setae, distoposterior corner rounded, posterior margin with 3 setae.</p><p>Pleopods: pleopod 1 (Fig. 16 B) peduncle lacking setae, with 2 coupling hooks; inner, outer rami with 12 and 15 segments respectively, basal segment of inner ramus with 2 weak clothes-pin setae. Pleopod 2 peduncle lacking setae, with 2 coupling hooks; inner, outer rami with 15, 15 segments respectively, basal segment of inner ramus with single weak clothes-pin seta. Pleopod 3 peduncle lacking setae, with 2 coupling hooks; inner, outer rami with 9, 9 segments respectively, basal segment of inner ramus with clothes-pin setae.</p><p>Urosome. Uropod 1 (Fig. 16 C): peduncle 1.6 × inner ramus in length, with 8 outer robust setae and inner robust seta; outer ramus subequal in length to inner, with 2 inner and 2 outer robust setae and 5 apical robust setae; inner ramus possessing 2 outer and 2 inner robust setae, and 5 apical robust setae.</p><p>Uropod 2 (Fig. 16 D): peduncle 1.2 × length of inner ramus, with 2 outer robust setae and 2 inner, paired robust setae; outer ramus approximately 60 % length of inner ramus with marginal robust seta, and 3 apical robust setae; inner ramus with marginal robust seta, 2 outer robust setae, and 5 apical robust setae.</p><p>Uropod 3 (Fig. 165 E): small, shorter than telson, uniramous; peduncle approximately 2 × length ramus, with 4 apical robust setae.</p><p>Telson (Fig. 16 F). Telson entire, elongated, 1.9 × longer than broad, subrectangular; apex with 8 robust setae, 2 plumose setae arise dorsolaterally from both outer margins, surface covered with small facial setae.</p><p>Male: allotype USNM 1456551 (SDC 008.02); Size 10.40 mm. Differing from female in several points, including antennae; gnathopod shape and setation; and the shape and setation of uropods 1 and 2. Structures not described below are as in female.</p><p>Antennae. Antenna: 50 % body length, 1.5 × longer than antenna 2; peduncle, flagellum lacking robust setae; primary flagellum with 21 segments. Antenna 2 (Fig. 17 A): gland cone distinct; peduncle subequal in length to flagellum, peduncle segment 4 subequal in length to segment 5; flagellum 12 - segmented, possessing robust setae on most segments, without small calceoli or aesthetasc-like structures apically on distal flagellar segments.</p><p>Gnathopods. Gnathopod 1 (Fig. 17 B): coxal plate with 5 apical setae; ischium with 6 setae and pubescence along posterior margin; carpus approximately 35 % length of propodus with robust seta along anterior margin and a pair of setae on anterodistal margin, one of which is approximately 40 % length of propodus, posterior margin with single group of plumose setae and 7 submarginal setae directed distally; propodus 1.4 × longer than broad, with 1 marginal anterior seta, 3 superior medial setae, proximal most paired, 4 setae inserted at anterodistal corner, 4 inferior medial setae and 3 groups of plumose posterior setae; palm oblique, concave, with serrate blade-like edge running the length, 6 outer and 7 inner bifid robust setae, 6 outer setae, and inner seta; inner margin of defining angle with 5 bifid robust setae, outer margin with 6 bifid robust setae; dactylus with outer seta and 5 short setae covering the inner margin and 2 setae placed along the inner margin at base of nail.</p><p>Gnathopod 2 (Fig. 17 C): coxal plate with 6 apical setae; ischium with 3 setae and pubescence along posterior margin; merus with pubescence along posterior surface and 4 posterodistal setae; carpus 80 % length of propodus, with robust seta along anterior margin and two setae on anterodistal margin, one of which is approximately 33 % length of propodus, posterior margin with 5 groups of plumose setae, distal-most bearing 5 rastellate setae, and 4 submarginal setae directed distally; propodus 1.3 × longer than broad, with marginal anterior seta, 5 superior medial setae, 6 setae inserted at anterodistal corner, 4 inferior medial setae, and 7 groups of plumose setae along posterior margin; palm weakly transverse, straight, with serrate blade-like edge running the length, 5 outer and 5 inner bifid robust setae, 4 outer setae, with inner seta; inner margin of defining angle with 7 bifid robust setae, outer margin with 6 bifid robust setae; dactylus with outer seta and 6 short setae covering the inner margin and 2 setae placed along the inner margin at base of nail.</p><p>Urosome. Uropod 1 (Fig. 18 A): peduncle 1.5 × inner ramus in length, with 12 outer robust setae and inner robust seta, posteromedial margin with distinct protuberance approximately 20 % of inner ramus in length, dorsal margin weakly serrate; outer ramus approximately 90 % length of inner, with 2 outer and 2 inner robust setae and 4 apical robust setae; inner ramus possessing 2 outer robust setae and inner robust seta, and 4 apical robust setae.</p><p>Uropod 2 (Fig. 18 B): peduncle 1.1 × inner ramus, with 3 outer robust setae and inner robust seta; outer ramus approximately 75 % length of inner ramus with marginal robust seta, and 3 apical robust setae; inner ramus inner margin with robust seta, outer margin with robust seta, and 5 apical robust setae.</p><p>Uropod 3 (Fig. 18 C): small, subeaqual in length to telson, uniramous; peduncle 1.4 × length of ramus, with marginal seta; ramus with 3 apical robust setae.</p><p>Telson (Fig. 18 D). Telson entire, elongated, 1.6 × longer than broad, weakly tapering distally; apex with 11 robust setae, outer most on each side deflected laterally, 2 plumose setae arise dorsolaterally from both outer margins, surface covered with small facial setae.</p><p>Variation.</p><p>This species varies slightly in several morphological characteristics, particularly between males and females (Table 3).</p><p>Molecular evidence for species status.</p><p>In mtDNA analyses (co 1 + 16 S), specimens from the Upper Patuxent River seep formed a distinct lineage within the S. tenuis species group and were recovered as sister to a S. tenuis potomacus sensu lato lineage (Fig. 11), with strong support. The new species was consistently delimited as a separate MOTU by ASAP, PTP, and mPTP analyses of mtDNA and the BPP analysis (mtDNA + 28 s) (Fig. 11). Mean uncorrected mtDNA p-distance between S. paveki sp. nov. and S. tenuis potomacus sensu lato was 3.5 %, and distances to other S. tenuis group taxa ranged from 7.3–15.7 %. Intraspecific mtDNA divergence within S. paveki was low (mean p-distance = 0.13 %).</p><p>Geographical distribution.</p><p>Stygobromus paveki sp. nov. is known only from the type locality, a hypotelminorheic seep adjacent to the southbound lanes of the Baltimore – Washington Parkway in Prince George’s County, Maryland, USA. The type locality lies within the Upper Patuxent River watershed (Fig. 1).</p><p>Habitat and ecology.</p><p>The type locality is a typical hypotelminorheic seep, identifiable as a slight depression in the woods. The seeps are dry at the surface in the summer, and the amphipods survive by burrowing into the colloidal clay that lines the seep (Gilbert et al. 2018).</p><p>Conservation.</p><p>Stygobromus paveki sp. nov. is known only from the type locality. The NatureServe conservation rank calculated is Critically Imperiled (G 1). Under IUCN Red List criteria, S. paveki sp. nov. was assessed as Critically Endangered (CR B 1 a, b) because of an extremely small EOO and AOO (known from a single seep). Major threats to the species include increased risk of human intrusion and disturbance, habitat degradation, and pollution due to the close proximity of the type locality to the Baltimore – Washington Parkway.</p></div>	https://treatment.plazi.org/id/BEE87AD8F9855E58B85948C68465DFB9	Public Domain	No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.		Pensoft via Plazi	Cannizzaro, Andrew G.;Sawicki, Thomas R.;Schaefer, Jacob;Castrillo, Dominique;Maxwell, Eric C.;Burch, Elizabeth;Culver, David C.;Niemiller, Matthew L.	Cannizzaro, Andrew G., Sawicki, Thomas R., Schaefer, Jacob, Castrillo, Dominique, Maxwell, Eric C., Burch, Elizabeth, Culver, David C., Niemiller, Matthew L. (2026): Two new species of Stygobromus Cope, 1872 (Amphipoda, Crangonyctidae) amphipods from hypotelminorheic seepage springs in the Washington, D. C., USA area. Subterranean Biology 57: 23-63, DOI: 10.3897/subtbiol.57.188080
BA981DA7931D5FA6AD9D69A285054C42.text	BA981DA7931D5FA6AD9D69A285054C42.taxon	http://purl.org/dc/dcmitype/Text	http://rs.tdwg.org/ontology/voc/SPMInfoItems#GeneralDescription	text/html	en	Stygobromus scottsruni Cannizzaro, Sawicki & Niemiller 2026	<div><p>Stygobromus scottsruni Cannizzaro, Sawicki &amp; Niemiller sp. nov.</p><p>Figs 4, 5, 6, 7, 8, 9, 10</p><p>Type material.</p><p>Holotype: • female, 6.85 mm, USA: Virginia, Fairfax County, <a href="https://tb.plazi.org/GgServer/search?materialsCitation.longitude=-77.2035&amp;materialsCitation.latitude=38.965" title="Search Plazi for locations around (long -77.2035/lat 38.965)">hypotelminorheic seep 4, Scott’s Run Nature Preserve</a> (38.9650°N, 77.2035°W), deposited in the National Museum of Natural History, Smithsonian Institution, Washington, D. C., USA (USNM 1456546). Collected 19 December 2022 by Dave C Culver; Thalia Eigen; Elizabeth Burch . Allotype: • male, 6.70 mm (USNM 1456549), same locality and collection data for male holotype: 1/9/2023, collected by D. C. Culver . Paratypes: • 1 female same locality, date collected 19 December 2022 (USNM 1456545), and • 1 male and 1 female same locality, date collected 9 January 2023 (USNM 1456547, USNM 1456548) .</p><p>Etymology.</p><p>The species name refers to Scott’s Run, a small tributary adjacent to the seeps draining to the Potomac River approximately 1 km from the type locality. The type locality occurs within the Difficult Run – Potomac River watershed (HUC 10; U. S. Geological Survey).</p><p>Type locality.</p><p>Hypotelminorheic seep 4, Scott’s Run Nature Preserve, Fairfax County, Virginia, USA (38.96501°N, 77.20347°W; Fig. 1). Seep 4 is part of a cluster of seeps found just past the Scotts Run crossing on the main trail leading to the river. A photo of the seep is shown in Fig. 2.</p><p>Diagnosis.</p><p>Small stygomorphic species allied with the S. tenuis species group. Stygobromus scottsruni sp. nov. is distinguished from S. hayi and S. allegheniensis by uropod 1 bearing a robust seta along the inner margin and by an entire telson that narrows slightly distally. It further differs from S. allegheniensis by the slightly convex bases of pereopods 5–7, and from S. hayi by having fewer than 10 robust setae along the apical margin of the telson. It differs from S. tenuis tenuis by the absence of a coxal gill on pereopod 7 and by the absence of a sternal gill on male pleonite 1. It differs from S. tenuis potomacus by body size (largest male 6.7 mm; largest female 9.4 mm). It differs from S. anacostensis by lacking aesthetasc-like structures on the flagellum of antenna 2, by the male antenna 2 being proportionally shorter than antenna 1, and by the more setose anterior and posterior margins of the bases of pereopods 3 and 4. It differs from S. paveki sp. nov. by a straight palmar margin on gnathopod 1 and by having fewer segments on the inner and outer rami of pleopods 1 and 3.</p><p>Stygobromus scottsruni sp. nov. can be further distinguished from all other members of the S. tenuis species group by the combination of: (1) bifurcate sternal gills; (2) telson lacking lateral spines; and (3) the posterodistal margin of the carpus of gnathopod 2 bearing rastellate seta (e).</p><p>Description.</p><p>Female: holotype, USNM 1456546 (SDC-004.03) (Fig. 3 A); Size 6.85 mm.</p><p>Antennae. Antenna 1 (Fig. 4 A): ~ 40 % body length, 1.2 × length of antenna 2; primary flagellum with 19 segments; aesthetascs on most segments, shorter than corresponding segments; accessory flagellum 2 - segmented, extending beyond first segment. Antenna 2 (Fig. 4 B): gland cone distinct; peduncle 1.6 × length of flagellum; robust setae on dorsal margins of peduncular segments 3–5; segment 4 subequal to segment 5; flagellum 9 - segmented, lacking robust setae.</p><p>Mouthparts (Figs 4 C, 4 D, 5 A – D). Mandibles: left mandible (Fig. 4 C) incisor 5 - dentate, lacinia mobilis 4 - dentate, with 5 robust serrate and numerous plumose accessory setae; molar process reduced with simple seta; palp with 3 segments, second segment 95 % length of third, with inner margin bearing 6 setae and sparse fine setae; segment 3 with 3 C-setae, 3 E-setae, 1 B-seta, and 8 D-setae, face with pubescent setae distally. Right Mandible (Fig. 4 D): incisor 4 - dentate, lacinia mobilis bifurcate, both lobes with numerous protuberances; accessory setae row with 4 robust, serrate setae and numerous plumose setae; molar process reduced with simple seta. Palp with 3 articles, relative articles length and setation patterns as in left mandible.</p><p>Lower Lip (Fig. 5 A): inner lobes distinct; outer margin of outer lobe sparsely covered in fine setae; inner margin of outer lobe heavily setose.</p><p>Maxilla 1 (Fig. 5 B): inner plate with 3 plumose marginal setae and numerous fine, pubescent setae covering entire plate; outer plate with 7 apical comb spines, pubescence covering inner margin, decreasing laterally and proximally; palp with 2 segments, distal segment covered in pubescence; subapical margin of distal article with 3 setae, apical margin with 5 setae.</p><p>Maxilla 2 (Fig. 5 C): both inner and outer plates covered in pubescent setae; outer plate not as wide as inner plate, with numerous distal setae; inner plate narrowing distally, with numerous apical setae and 3 large plumose facial setae.</p><p>Maxilliped (Fig. 5 D): inner plate shorter than outer plate, with 4 naked cuspidate setae, and 3 palmate robust setae along apical margin, surface of plate covered in fine pubescence; outer plate armed with numerous setae covering inner and apical margins; palp second segment with numerous marginal setae, third article with numerous marginal / submarginal setae; dactyl with 1 outer seta and 1 inner seta.</p><p>Gnathopods. Gnathopod 1 (Fig. 6 A): coxal plate with 4 apical setae; basis with long setae inserted along anterior, and posterior margins, small patch of pubescence on distomedial surface; ischium with 5 setae and pubescence along posterior margin; merus pubescent along posterior surface, numerous distal setae, and robust seta along anterior margin; carpus approximately 50 % length of propodus with robust seta along anterior margin and 2 setae on anterodistal margin, one of which is approximately 50 % length of propodus, posterior margin with single group of plumose setae and 8 submarginal setae directed distally; propodus 1.5 × longer than broad, with 1 marginal anterior seta, 3 superior medial setae, 5 setae inserted at anterodistal corner, 5 inferior medial setae and numerous plumose posterior setae; palm oblique, straight, with serrate blade-like edge running the length, 6 outer and 6 inner bifid robust setae, 8 outer setae, and inner seta; inner margin of defining angle with 5 bifid robust setae, outer margin with 5 bifid robust setae; dactylus with outer seta and 6 short setae covering the entire inner margin and 2 setae placed along the inner margin at base of nail.</p><p>Gnathopod 2 (Fig. 6 B): coxal plate with 6 apical setae; basis with long setae inserted along anterior, and posterior margins, small patch of pubescence on posterodistal corner; ischium with 6 setae and pubescence along posterior margin; merus with pubescence covering posterior surface and 6 posterodistal setae; carpus approximately 95 % length of propodus, with robust seta along anterior margin and two setae on anterodistal margin, one of which is approximately 55 % length of propodus, posterior margin with 4 groups of plumose setae, distal-most bearing 3 rastellate setae, and 3 submarginal setae directed distally; propodus 1.2 × longer than broad, with marginal anterior seta, 4 superior medial setae, 5 setae inserted at anterodistal corner, 5 inferior medial setae, and 7 groups of plumose setae along posterior margin; palm weakly transverse, straight, with serrate blade-like edge running the length, 5 outer and 5 inner bifid robust setae, 2 outer setae, without inner setae; defining angle with 5 outer and 5 inner bifid robust setae; dactylus with outer seta and 4 short setae covering the entire inner margin and 3 setae placed along the inner margin at base of nail.</p><p>Pereopods. Pereopod 3 (Fig. 7 A): coxal plate with 7 apical setae; basis with numerous long setae placed along both anterior and posterior margins; merus 1.4 × longer than carpus, carpus approximately 80 % of propodus in length; dactylus approximately 45 % length of propodus, with plumose seta on anterior margin, seta placed along posterior margin followed by thin seta on medial margin.</p><p>Pereopod 4 (Fig. 7 B): coxal plate armed with 3 anterior and 3 posterior apical setae; basis with numerous long setae placed along both anterior and posterior margins; merus approximately 1.2 × longer than carpus; carpus approximately 90 % length of propodus; dactylus approximately 45 % length of propodus, setation as in pereopod 3.</p><p>Pereopod 5 (Fig. 7 C): coxal plate large, bilobate with distinct anterior and posterior lobes, posterior lobe with 3 robust setae on distal corner and 2 setae along anterodistal margin; basis posterior margin weakly convex with 7 shallow serrations, anterior margin with 4 split-tipped robust setae and 2 distal split-tipped setae; merus subequal in length to carpus; carpus subequal to propodus; dactylus approximately 50 % length of propodus, with plumose seta on posterior margin, seta placed along anterior margin, followed by thin seta on medial margin.</p><p>Pereopod 6 (Fig. 7 D): coxal plate bilobate, with weakly produced anterior lobe, posterior lobe bearing 2 robust and one simple apical seta (e); basis posterior straight with 11 weak serrations, anterior margin with 7 split-tipped robust setae, and 2 robust and one simple seta (e) at anterodistal corner; merus subequal in length to carpus; carpus subequal in length to propodus; dactylus approximately 33 % length of propodus, setation as in pereopod 5.</p><p>Pereopod 7 (Fig. 7 E): coxal plate small, subtriangular, with 4 posterior setae; basis posterior margin weakly convex with 10 weak serrations and convex distal corner, anterior margin with 8 split-tipped robust setae, and 3 robust setae at anterodistal corner; merus 90 % length of carpus; carpus approximately 90 % length of propodus, dactylus approximately 20 % length of propodus, setation as in pereopods 5, 6.</p><p>Gills and broodplates (Figs 6 B, 7 D 1, E 1). coxal gills on somites 2–6, somites 6 and 7 with bifurcate sternal gills. Brood plates ovate, setaceous, present on somites 2–5, decreasing in size posteriorly.</p><p>Pleon. Epimera (Fig. 8 A): first epimeron ventral margin with 2 robust setae, distoposterior corner rounded, posterior margin with 3 setae, 2 of which are placed near distoposterior corner. Second epimeron ventral margin with 3 robust setae, distoposterior corner rounded, posterior margin with 3 setae, 2 of which are placed near distoposterior corner. Third epimeron ventral margin with 4 robust setae, distoposterior corner rounded, posterior margin with 2 setae.</p><p>Pleopods: pleopod 1 (Fig. 8 B) peduncle lacking setae, with 2 coupling hooks; inner, outer rami with 9 and 12 segments respectively, basal segment of inner ramus with 3 weak clothes-pin setae. Pleopod 2 peduncle lacking setae, with 2 coupling hooks; inner, outer rami with 8, 11 segments respectively, basal segment of inner ramus with single weak clothes-pin seta. Pleopod 3 peduncle lacking setae, with 2 coupling hooks; inner, outer rami with 6, 7 segments respectively, basal segment of inner ramus without clothes-pin setae.</p><p>Urosome. Uropod 1 (Fig. 8 C): peduncle 1.5 × inner ramus in length, with 10 outer robust setae and inner robust seta; outer ramus approximately 95 % length of inner, with 2 inner and 2 outer robust setae and 5 apical robust setae; inner ramus possessing 2 outer and 2 inner robust setae, and 4 apical robust setae.</p><p>Uropod 2 (Fig. 8 D): peduncle 95 % length of inner ramus, with 3 outer robust setae and an inner robust seta; outer ramus approximately 65 % length of inner ramus with marginal robust seta, and 4 apical robust setae; inner ramus with marginal robust seta and 5 apical robust setae.</p><p>Uropod 3 (Fig. 8 E): small, shorter than telson, uniramous; peduncle approximately 2 × length of ramus with proximal seta; ramus with 2 apical robust setae.</p><p>Telson (Fig. 8 F). Telson entire, elongated, 2 × longer than broad, weakly tapering distally; apex with 8 robust setae, 2 plumose setae arise dorsolaterally from both outer margins, surface covered with small facial setae.</p><p>Male: allotype USNM 1456549 (SDC-005.07) (Fig. 3 B); Size 6.7 mm. Differing from female in several points, including antennae; gnathopod shape and setation; and the shape and setation of uropods 1 and 2. Structures not described below are as in female.</p><p>Antennae. Antenna 1 (not illustrated but see Fig. 3 B): 50 % body length, 1.5 × longer than antenna 2; peduncle, flagellum lacking robust setae; primary flagellum with 16 segments. Antenna 2 (Fig. 9 A): gland cone distinct; peduncle 1.6 × longer than flagellum, peduncle segment 4 subequal in length to segment 5; flagellum 8 - segmented, lacking robust setae, without small calceoli or aesthetasc-like structures apically on distal flagellar segments.</p><p>Gnathopods. Gnathopod 1 (Fig. 9 B): coxal plate proximal side damaged, with minimum of 2 apical setae; ischium with 4 setae and pubescence along posterior margin; carpus approximately 50 % length of propodus with robust seta along anterior margin and a pair of setae on anterodistal margin, one of which is approximately 55 % length of propodus, posterior margin with single group of plumose setae and 5 submarginal setae directed distally; propodus 1.6 × longer than broad, with 1 marginal anterior seta, 3 superior medial setae, 4 setae inserted at anterodistal corner, 4 inferior medial setae and 3 groups of plumose posterior setae; palm oblique, weakly concave, with serrate blade-like edge running the length, 5 outer and 5 inner bifid robust setae, 5 outer setae, and inner seta; inner margin of defining angle with 3 bifid robust setae, outer margin with 4 bifid robust setae; dactylus with outer seta and 6 short setae covering the inner margin and 2 setae placed along the inner margin at base of nail.</p><p>Gnathopod 2 (Fig. 9 C): coxal plate with 5 apical setae; ischium with 3 setae and pubescence along posterior margin; merus with pubescence covering posterior surface and 4 posterodistal setae; carpus 70 % length of propodus, with robust seta along anterior margin and two setae on anterodistal margin, one of which is approximately 37 % length of propodus, posterior margin with 3 groups of plumose setae, distal-most bearing 3 rastellate setae, and 3 submarginal setae directed distally; propodus 1.4 × longer than broad, without marginal anterior seta, 4 superior medial setae, 4 setae inserted at anterodistal corner, 3 inferior medial setae, and 4 groups of plumose setae along posterior margin; palm oblique, straight, with serrate blade-like edge running the length, 3 outer and 4 inner bifid robust setae, 4 outer setae, without inner setae; inner and outer margins of defining angle each with 4 bifid robust setae; dactylus with outer seta and 5 short setae covering the inner margin and 2 setae placed along the inner margin at base of nail.</p><p>Urosome. Uropod 1 (Fig. 10 A): peduncle 1.3 × inner ramus in length, with 6 outer robust setae and inner robust seta, posteromedial margin with distinct protuberance approximately 25 % of inner ramus in length, dorsal margin weakly serrate; outer ramus approximately 90 % length of inner, with 2 outer and 1 inner robust seta (e) and 4 apical robust setae; inner ramus possessing 1 outer and 1 inner robust seta, and 4 apical robust setae.</p><p>Uropod 2 (Fig. 10 B): peduncle 1.2 × inner ramus, with 2 outer robust setae and inner robust seta; outer ramus approximately 70 % length of inner ramus with marginal robust seta, and 4 apical robust setae; inner ramus with marginal robust seta and 4 apical robust setae.</p><p>Uropod 3 (Fig. 10 C): small, shorter than telson, uniramous; peduncle 1.7 × length of ramus, with 2 marginal setae; ramus with 2 apical robust setae.</p><p>Telson (Fig. 10 D). Telson entire, elongated, 2 × longer than broad, weakly tapering distally; apex with 8 robust setae, 2 plumose setae arise dorsolaterally from both outer margins, surface covered with small facial setae.</p><p>Variation.</p><p>This species varies slightly in several morphological characteristics, particularly between males and females (Table 3).</p><p>Molecular evidence for species status.</p><p>In mitochondrial phylogenetic analyses based on the concatenated co 1 + 16 S dataset, all specimens from the Scott’s Run type locality formed an exclusive lineage within the S. tenuis species group (Fig. 11). This lineage was recovered as distinct from other sampled regional congeners and was supported as a separate MOTU by ASAP, PTP, mPTP analyses of mtDNA and the BPP analysis (mtDNA + 28 s) (Fig. 11). Mean uncorrected mtDNA p-distance between S. scottsruni sp. nov. and other members of the S. tenuis species group ranged from 7.7–15.3 %; intraspecific mtDNA divergence within S. scottsruni was low (mean p-distance 0.02 %).</p><p>Geographical distribution.</p><p>Stygobromus scottsruni sp. nov. is known only from the type locality, hypotelminorheic seep 4 at Scott’s Run Nature Preserve in Fairfax County, Virginia, USA (Fig. 2). Scott’s Run Nature Preserve is a 336 - acre preserve in the Fairfax County Park Authority system located on the south side of the Potomac River (Fig. 1).</p><p>Habitat and ecology.</p><p>The complex of seeps along Scotts Run is a very typical set of hypotelminorheic habitats, whose surface manifestation is little more than a wet spot in the woods (Fig. 2). The seeps become dry at the surface in the summer, and the amphipods survive by burrowing into the colloidal clay that lines the seep (Gilbert et al. 2018).</p><p>Conservation.</p><p>Stygobromus scottsruni sp. nov. is known only from the type locality. The NatureServe conservation rank calculated is Critically Imperiled (G 1). Under IUCN Red List criteria, S. scottsruni sp. nov. was assessed as Critically Endangered (CR B 1 a, b) because of an extremely small EOO and AOO (known from a single seep). The site is subject to habitat disruption (primarily compaction) by hikers and by pollution of nearby Scotts Run. The type locality population receives some protection because it occurs within a designated nature preserve.</p></div>	https://treatment.plazi.org/id/BA981DA7931D5FA6AD9D69A285054C42	Public Domain	No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.		Pensoft via Plazi	Cannizzaro, Andrew G.;Sawicki, Thomas R.;Schaefer, Jacob;Castrillo, Dominique;Maxwell, Eric C.;Burch, Elizabeth;Culver, David C.;Niemiller, Matthew L.	Cannizzaro, Andrew G., Sawicki, Thomas R., Schaefer, Jacob, Castrillo, Dominique, Maxwell, Eric C., Burch, Elizabeth, Culver, David C., Niemiller, Matthew L. (2026): Two new species of Stygobromus Cope, 1872 (Amphipoda, Crangonyctidae) amphipods from hypotelminorheic seepage springs in the Washington, D. C., USA area. Subterranean Biology 57: 23-63, DOI: 10.3897/subtbiol.57.188080
