Texanobathynella coloradoensis, Camacho & Mas-Peinado & Hutchins & Schwartz & Dorda & Casado & Rey, 2021

Camacho, A. I., Mas-Peinado, P., Hutchins, B. T., Schwartz, B. F., Dorda, B. A., Casado, A. & Rey, I., 2021, New stygofauna from Texas, USA: three new species of Parabathynellidae (Crustacea: Bathynellacea), Journal of Natural History 55 (15 - 16), pp. 979-1007 : 997-999

Texanobathynella coloradoensis sp. nov. Camacho and Hutchins, 2020

http://zoobank.org/urn:lsid:zoobank.org:act: 9993A16 C-72D9-43FB-9134-

C647A4F57AB0

Material examined ( Table 1)

Type locality. Colorado River , Bastrop County, Texas, USA ( WGS 84 30.11187ºN, − 97.32775ºE, 94 m amsl): holotype male ( MNCN 20.04 /20169 slide and MNCN / ADN 54869 DNA extract) and two male and one female paratypes ( MNCN 20.04 /20170- ADN 54867, MNCN 20.04 /20171- ADN 54870 and MNCN / ADN 54868) ( Table 1) . Coll . by B. Hutchins , R . Jose, A. Swink and B . Schwartz , 29 March 2017 (sample 170.329-H3) .

Description. Body elongated, segments widening towards posterior end. Head longer than broad.

Antennule ( Figure 6 (a)) 6-segmented; last three segments almost as long as first three combined; first segment longest, second and third segments similar to last two, fourth segment shortest; inner flagellum almost square; setation as in Figure 6 (a); fifth segment with two aesthetascs, segment 6 with three terminal aesthetascs.

Antenna ( Figure 6 (b)) 3-segmented; all segments similar in length; first two segments without setae, third slightly longer than the other two and with two terminal and one median setae.

Labrum ( Figure 6 (c)). Almost flat, with eight main teeth, and two lateral (bicuspidate) teeth at each angle.

Mandible ( Figure 6 (d)). Pars incisiva with six well-developed teeth and a small triangular proximal tooth as in Figure 6 (d); pars molaris with six strong claws, the two most proximal setulose, smaller and joined basally; mandibular palp not exceeding pars incisiva.

Maxillule ( Figure 6 (e)). Proximal endite with four unequal claws; distal endite with five claws, of which two apical smooth, the rest denticulate; three simple, unequal setae subdistally on outer margin of endite, as figured.

Maxilla ( Figure 6 (f)) 3-segmented; setal formula: 1, 2 + 1, 12.

Thoracopods I–VII ( Figure 7 (a–g)). Well developed; length gradually increasing from ThI to ThIII ( Figure 7 (a–d)); ThIV ( Figure 7 (d)) through VII ( Figure 7 (g)) of similar length but shorter than ThIII; ThI without epipod; well developed epipod on ThII to VII, slightly surpassing half length of basipod. Basipod of all Ths with one smooth terminal seta similar in length to first segment of corresponding endopod. Exopod 2-segmented (ThI; Figure 7 (a)) or 3-segmented ThII to ThVII; Figure 7 (b)–g); exopod of ThI to VII shorter than corresponding endopod; all exopodal segments with one barbed seta (with groups of ctenidia at base) and one short and smooth outer seta except on last segment, which has a long barbed seta and another shorter plumose seta. Endopod of ThI 4-segmented, first segment small; second and third long and similar in length, both with cluster of strong spinules along outer margin; fourth segment reduced with two smooth strong claws and one simple seta; outer seta on second segment of endopod of ThI–VII plumose. Setal formula of endopod:

ThI 2 + 0/0 + 0/0 + 0/3(1)

ThII–VII 0 + 0/0 + 1/0 + 0/3(1)

Male thoracopod VIII ( Figure 6 (g–j)). Almost square. Basal region prolonged anteriorly in penial complex, with three lobes: a subrectangular outer lobe almost completely fused to basipod, placed next to the exopod in internal view; a dentate lobe with rounded distal end covered with small terminal teeth; and an almost triangular inner lobe. Basipod with ‘bilobed crest’; endopod small with two terminal setae and seta at base; exopod reduced to a small conical process.

Pleotelson. Without ventral seta. Anal operculum not pronounced, almost flat.

First pleopods. Absent.

Uropod ( Figure 7 (h)). Sympod 3.5 times as long as wide and 1.5 times longer than rami, latter almost equal in length and with six unequal barbed spines, two distal-most almost 3 times longer than rest; endopod terminating in lancet-shaped spine and with two barbed and one plumose setae at base; exopod with three barbed setae.

Furca ( Figure 7 (i)). Rami almost triangular, with seven barbed spines, distal-most longest; two unequal plumose setae disposed dorsally, of which shortest not reaching tip of terminal spines.

Etymology. The specific name, coloradoensis , refers to the Colorado River where the new species was found.

Figures

Figure 6. Texanobathynella coloradoensis sp. nov. Male holotype. (a) Antennule (dorsal view); (b) female antenna (dorsal view); (c) labrum; (d) mandible; (e) maxillule; (f) maxilla; (g–j) male ThVIII (different views).

Figure 7. Texanobathynella coloradoensis sp. nov. Male holotype. (a) Thoracopod I; (b) thoracopod II; (c) thoracopod II; (d) thoracopod IV; (e) thoracopod V; (f) thoracopod VI; (g) thoracopod VII; (h) uropod; (i) furca (dorsal view).