Annotated Checklist of the large branchiopod crustaceans of Idaho, Oregon and Washington, USA, with the “ rediscovery ” of a new species of Branchinecta (Anostraca: Branchinectidae) Rogers, D. Christopher Hill, Matthew A. Zootaxa 2013 3694 3 249 261 N6GP [151,431,1757,1783] Branchiopoda Branchinectidae Branchinecta Animalia Anostraca 3 252 Arthropoda species lutulenta sp. nov.   Etymology. The specific epithet comes from the Latin adjective; “ lutulentus, -a, -um” meaning “muddy”. Lynch probably chose this name to reflect the thick, sticky, saline mud where the habitat of this fairy shrimp occurs. The common name that he gave this animal was the “muddy fairy shrimp”. Lynch spelled the name “lutalenta” on his handwritten labels in the specimen vials, which we assume is a misspelling, since his copious slide mounted material was labeled “ lutulenta”.    Typelocality. Both pools occur in poorly drained flood plain alluvium. The surrounding soil substrate has 15% carbonate content and the salinity (as electrical conductivity) is 8.0 mmhos/cm. The pools are alkaline. Water quality data was collected 28 March 2011. The upper and lower pools had conductivities of 3.2 mmhos/cm and 2.2 mmhos/cm and pH values of 8.89 and 8.58, respectively. The upper pool was approximately 16min greatest diameter and 10cmdeep. The lower pool was approximately 30min greatest diameter and 30cmdeep. The upper pool flowed into the lower pool via a 1 meterwide by 2cmdeep vegetated channel.  B. lutulenta  sp. nov.was the only anostracan species present in the upper pool and co-occurring with  Branchinecta mackiniin the lower pool, the latter being much more common. Water samples collected from the site were analyzed in the lab and found to have a salinity of 0.10%.   Typematerial. Holotype.Male, data: USA: WASHINGTON: Grant Co.: 46˚ 49’ 55.65” N, 119˚ 47’ 31.14”W; pool approximately 150mnorth of Lower Crab Creek Road, approximately 15mwest of fishing access road, and approximately 18msouth of Crab Creek, south of Jericho; pool composed of an upper small pool, which drained into a larger lower pool, USNM 1207958.   Paratypes.One male, one female, same data: USNM 1207959.  Material examined. USA: WASHINGTON: Grant Co.: (From the original label) “pond 1.2 milewest of Smyrna”, USNM-00256561, 50 males, 50 females; (From the original label) “ 12.1 mileE of Beverley and 1.9 mileW of Smyrina (sic), pond” USNM-00170212, 50 males, 50 females; Pools at 46˚ 49’ 55.65” N, 119˚ 47’ 31.14”W, 28 March 2011, 21 males, 11 females, M. A. Hill; Pools at 46˚ 49’ 55.65” N, 119˚ 47’ 31.14” W, 29 August 2012, 14 males, 9 females, reared from soil collected by M. A. Hill. In addition we examined 26 slide mounted specimens prepared by Lynch. These slides presented the second antennae, the thoracopods of both males and females, the brood pouch and the cercopods. Unfortunately, due to the age of the slides and how they were stored after Lynch’s death, the value of the slides was negligible.   Description. Male.( Figure 1A–F) Average length (from anterior margin o head to posterior margin of telson, not including cercopods) of preserved material 22 mm.  Headrounded, anteriolateral corners not projecting over compound eye peduncles.  Labrumsmooth, rounded, and directed posteriorly.  Mandibles and maxillaetypical for the non-predatory members of the genus.  First antenna1.25 times as long as stalked compound eye, with apex truncated, bearing four to six setae.  Second antennaeextending posteriorly to fifth thoracic segment. Second antennal proximal antennomere subcylindrical, approximately four times as long as broad. Medial surface generally with small, scattered spinules. Apophysis absent. Anteriomedial pulvillus present. Second antennal distal antennomere subequal in length to proximal antennomere, laterally flattened, arcing medially, curving evenly along its length, broadening distally. Distal antennomere bent anteriorly in proximal third. Posterior margin expanded slightly in distal third, truncating towards apex. Apex broadly rounded, and twisted so that the medial surface is directed anteriorly, and the lateral surface directed posteriorly. Medial margin of apex folded back, medially, giving apex a trilobed appearance. Rasp absent.  Thoracopodsserially homologous, increasing in size from the anterior pair to the fifth pair, then decreasing in size posteriorly to the eleventh pair. Praeepipodites and epipodites typical for genus. Thoracopod I with exopodite broadly oval and the endopodite triangular. Thoracopod V with exopodite oval, but arcing laterally, with a rounded apex; endopodite broad, elongate, arcing medially. Thoracopod XI with exopodite oval. Endopodite subtriangular.  Genital segmentssmooth and typical for the genus. Gonopods each with basal portion bearing a large ventral subconical, ventroposteriorly directed lobe, and a ventromedial digitiform spur. Everted gonopods extending to the second abdominal segment. Apices of everted gonopods bearing two lateral, spine covered mounds, each bearing ten to fifteen recurved spinules about one fourth as long as mound. Testes extending from genital segments (thoracic segments XII and XIII) posteriorly to abdominal segment IV.  Cercopodsas typical for the non-predatory members of the genus.  Female.( Figure 1G, H, and I) Average length of preserved material (from anterior margin o head to posterior margin of telson, not including cercopods) 17 mm.  Headwithout dorsal protuberances. Anterior surface of head and labrum with fine spinules. Labrum, mandibles and maxillae as in male.   FIGURE 1.  Branchinecta lutulenta  sp. nov.Male: A, left side of head, anterior view, with second antenna distal antennomere slightly rotated to show lateral aspect; B, apex of second antenna, distal view (medial side at top); C, left second antennal distal antennomere lateral view; D, posterior edge view; E, medial view; F, left thoracopod V, anterior view (without setation). Female: G, left thoracopod V, anterior view (without setation); H, left side of head, anterior view; I, whole animal, right side, lateral view.  First antennaesubequal in length to second antennae.  Second antennaesmooth, without any protrusions. Apex acute, tapering to a short point.. Thoraxwith rounded, conical dorsolateral projections on segments III–VII. Projections on thoracic segments III–VI similar in size and shape. Projection on thoracic segment VII one third the size of preceding segments. Thoracopodsgenerally similar to male, save that the endopodites and exopodites are more ovate and not elongated.  Genital segments and abdominal segmentssmooth. Brood pouch fusiform and smooth. Brood pouch extending to abdominal segment five or six. Ovaries biramal, extending anteriorly into thoracic segment VI, and posteriorly into abdominal segment IV or V.  Cercopodsas typical for the genus.  Egg. Approximately 300 µm in diameter, with dense, small, shallow, rounded depressions 0.1–0.25 times the diameter of the egg.  Differential diagnosis.  Branchinecta lutulenta  sp. nov.is separated from all other  Branchinectaspecies by the form of the male second antenna apex, which is rotated so that the medial surface is facing anteriorly, and by the medial fold in the apex, giving a trilobed appearance. Some South American species have a truly trilobed apex on the second antenna. However, in those species the apex is neither rotated nor folded. Males are most similar to  B. lindahliPackard, 1883,  B. sandiegonensisFugate, 1993and  B. oterosanvicenteiObregón-Barboza et al., 2002in that they share a very similar second antennal proximal antennomere, and the broad, laterally flattened distal antennomere. However, the apex in these species is not rotated and folded. Females are most similar to  B. lindahliand  B. oterosanvicentei, but can be separated by the dorsolateral projections (most clearly obvious in mature specimens) being limited to thoracic segments III–VII, as opposed to IV–XI in  B. lindahliand  B. oterosanvinceti.   Comments.The anostracan family Branchinectidaeand the genus  Branchinectawere recently redefined (Rogers and Coronel 2011). We describe here a new  Branchinectaspecies, originally discovered in 1959 from two wetlands, but not seen again. We rediscovered this species after extensive field surveys in the vicinity of the original collecting sites. James E. Lynch ( 1892–1975), Professor Emeritus of the College of Fisheries, University of Washington was an important figure in  Branchinectaand  Lepidurustaxonomy. He was an expert in Branchiopod crustaceans, as well as echinophilous ciliates (see Lynn and Berger 1973) and acanthocephalans (Lynch 1936, Van Cleave and Lynch 1950). Lynch discovered and described four species of  Branchinectafrom the Pacific Northwest of the USA(1937, 1958, 1960, 1972a), and after untangling the confusion created by Packard (1874, 1883) and Pearse (1912, 1918), redescribed three species according to modern standards (Lynch, 1958, 1964). Lynch’s work provided the basis for taxonomic evaluation of the  Branchinectaspecies (Lynch, 1972a). Lynch used to travel from his home in western Washington State to visit his sister in Spokane. On these trips, he would take various routes across the desert portions of the ColumbiaPlateau and collect branchiopod crustaceans (Lynch’s notes, USNM). In 1959, he collected an undescribed species of  Branchinectafrom two pools between Beverley and Smyrna. The material was deposited at the USNM after his death. Lynch had designated the material with a scientific and a common name, and we retain both. In both of Lynch’s collections as well as our own,  B. lutulenta  sp. nov.was found cöoccurring with  B. mackiniDexter, 1956. Both species are of similar age and density in all collections. One of us (DCR) made efforts to find Lynch’s original  B. lutulenta  sp. nov.localities, or additional populations in the Beverly/ Smyrna/ Royal City vicinity in 1997, 1998, 1999, 2000, 2002, 2007 and 2008. One of us (MH) conducted separate surveys in 2007, 2008 and 2009and successfully found our population in 2011. It was noted that Lynch’s site 1.2 milesWest of Smyrna was likely destroyed by the digging of a quarry and associated drainage structures. The site 1.9 mileswest of Smyrna possesses numerous clear, grassy pools devoid of anostracans along the railroad bed. A small pool here formed by a wheel rut in a dirt road contained  Branchinecta mackiniwhen sampled on 28 March 2011. The fate of Lynch’s original sites are unknown.