Branchinecta mediospinosa, Rogers, Christopher, Dasis, Don & Murrow, Daniel G., 2011

Rogers, Christopher, Dasis, Don & Murrow, Daniel G., 2011, A new species of Branchinecta (Crustacea: Anostraca) with comments on the large branchiopod crustaceans of Kansas, Zootaxa 2749, pp. 62-68 : 63-65

Branchinecta mediospinosa n. sp.

Figure 1 .

Etymology. The name “ mediospinosa ” refers to the salient identifying morphological character of the male. The gender is feminine.

Type locality. The type locality was an artificial temporary pool in a drainage ditch that received water run off from adjacent agricultural fields, planted in corn the summer before the time of collection, and from the adjacent roadway. The ditch did not support any hydrophytic vegetation. This site was modified sometime before 20 June 2009: a drainage ditch was excavated connecting the site with the Wichita Valley Center Floodway ostensibly to improve the area drainage. The function of the floodway system is to divert floodwaters from the Arkansas River to prevent flooding in the City of Wichita. Soil from the site was collected in the hope that viable eggs will be recovered.

Other organisms that occurred in the pool during the summer rainfall include the fairy shrimp Streptocephalus sealii Ryder, 1879 , Thamnocephalus platyurus Packard, 1877 , spinicaudatan clam shrimp of the genus Cyzicus , and juvenile crayfish ( Cambaridae ), predaceous diving beetles ( Dytiscidae ), backswimmers ( Notonectidae , Buenoa sp.), and dragonfly nymphs (Odonata).

Type material. Holotype, Male, data: USA: Kansas: Sedgwick Co.: Haysville: temporary pool in artificial roadside drainage, 37° 35’ 20” N, 97° 22’ 24” W, 1260 m, November 2007, D. Dasis, deposited: Kansas University Museum of Natural History Type no. KUIZ #003331. Allotype, female; same data as holotype. Deposited: Kansas University Museum of Natural History Type no. KUIZ #003332. Paratypes: same data as holotype, 5 females, 2 males; Deposited: Kansas University Museum of Natural History no. KUIZ #003333. Paratypes, 2 males, 8 females, 1 gynandromorph: same data as holotype, deposited: Collections of D.C. Rogers, DCR #692.

Diagnosis. Average length of preserved material: 10.1 mm from apex of head to apex of telson (males averaging 10.2, females averaging 9.9). Male. Second antennal proximal antennomere with a smooth, medial projection that bears a proximally directed, spiniform apex. Pulvilli transverse and situated on hemispherical projections. Female. Thoracic segments IV to X with dorsolateral hemispherical projections. Head lacking cornified projections.

Description. Male. Head with anterolateral corner projecting over base of eyestalk. Labrum covered with small evenly spaced spinules.

First antenna approximately 50% the length of second antennae proximal antennomere.

Second antenna capable of extending back to thoracopod IV or V. Second antennal proximal antennomere with a medial, smooth, proximally directed projection, with a spiniform apex. Medial projection in the apical 50% of the antennomere. Apophyses absent. Pulvilli transverse, positioned basally and anteromedially, densely covered in fine spinulae, and situated on hemispherical projections. Proximedial surface with scattered, evenly spaced, small spinules. Spinules covering some of the antennomere anterior surface adjacent to pulvillus. Second antennal distal antennomere subequal in length to proximal antennomere, flattened laterally, arcing medially in the proximal third, distal two thirds straight, and apex bent medially. Apex with tip subacute, directed posteriorly, anterior margin arcuate. Apex posteriomedial margin with a chitinized longitudinal pad. Apex anteriodistal margin with a rasp.

Maxillae lobiform with 4 to 6 apical setae.

Gen ital segment with single ventrolateral conical protuberance on each side. Everted gonopods short, extending nearly to the posterior margin of the first abdominal segment. Gonopods each with a single medial basal spiniform projection. Everted gonopod apex with two chitinized transverse crests; one apical one subapical on the dorsal side. Both crests dorsal to the apical gonopore, each bearing five or six spines.

Endopodites subtriangular. Epipodite elongated and oval.

Female. Head rounded, with anterolateral corners projecting over base of eyestalk.

First antenna subequal in length to second antenna.

Second antenna subcylindrical, with a distally directed lateral bulge, bearing a few small spinules. Distal end anteriorly curved and apically acute. Second antennae with a few scattered spinules in small clusters before the apex. Head without dorsal cornified protuberances.

Thorax with conical dorsolateral lobes on segments IV to X, with those on segments VIII to X or IX and X smaller than the anterior ones.

Broodpouch fusiform, extending to postgenital abdominal segment four or five. Endopodites ovate. Epipodite ovate.

Egg spherical, diameter approximately 250 μm, with angular, oval surface depressions diameter 20μm, some depressions joined.

Distribution and habitat. Branchinecta mediospinosa has been collected only from the type locality in Kansas. Additional surveys need to be conducted to ascertain if this species occurs in any other habitats. However, as it currently stands, this species meets the criteria under the IUCN Red List as Critically Endangered (CR), with the area of occupancy less than 10 km 2, known only to exist at a single site (B2), and observed decline in extent of occurrence, occupancy and quality of habitat (ab(i, ii, iii)).

Figures

FIGURE 1. Branchinecta mediospinosa n. sp. Types A) Male, left side of head anterior view, upper arrow indicates pulvillus, lower arrow indicates medial projection. B) Female, anterior view. C) Male second antenna distal antennomere apex, apical view. D) Same, medial view. E) Same, posterior view. F) Male left gonopod, everted, ventrolateral view. G) Female right lateral view, bracket indicates thoracic lobes. Scale bar represents 1 mm for A and B, 0.5 mm for C, D, E, 0.25 mm for F, and 2 mm for G.