Texicerberus castilloi Hutchins and Schwartz, 2021

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Suggested Common Name: San Marcos Texas Cerberus
Etymology: after Victor Castillo III from the Edwards Aquifer Research and Data Center (Texas State University). Common name refers to the San Marcos Spring Complex, where this species occurs.
Taxonomic History: Texicerberus castilloi Hutchins and Schwartz, 2021
Size Range: to 1.5mm
Description: (modified from Hutchins, Schwartz & Coleman, 2021) Head 1.2x as long as wide, 0.1x as long as body, with 1 posterolateral dorsal seta. Antenna 1 directed anterolaterally, 0.13x as long as body; peduncle 3-segmented, segments 1-2 similar in length, segment 2 with 1 distal and 3 mediolateral setae, segment 3 with 3 short distolateral simple setae and 1 distal aesthetasc; flagellum 3-segmented, segments shorter than peduncle segments, segment 3 shorter than segment 3 with 3-septate aesthetasc nearly as long as entire antenna 1 along with 3 short and 1 long simple distal setae. Antenna 2 2.1x longer than antenna 1, 0.3x as long as body; peduncle 6-segmented, 0.8x as long as entire antenna 2, segment 1 small, obscured under head in dorsal view, segment 3 rhombic, widest near base, lacking medial spine, with 4 simple distal setae, segments 4-5 with 1-several simple apical setae, segment 6 with 3 distal and 3 medial simple setae along with 1 distal aesthetasc; flagellum 8-segmented, segments shorter than peduncle segments, segments 1-7 with 0-2 apical simple setae, segment 8 with 2 apical simple setae and 1 apical aesthetasc. Maxilliped basis lobe extending past segment 1; palp segments 1-4 with 0-1 distomedial simple setae, segments 2-4 similar in lengths, longer than segments 1 and 5, segment 5 with 3 distal and 2 subapical simple setae. Pereonite 1 0.6x as long as head and about as wide or wider than head, tapering posteriorly, with 1 anterolateral simple seta. Pereopod 1 inserted anterolaterally; dactyl (with claw) 0.7x as long as propus with 2 short simple distovetral setae and ventral row of short simple setae, claw 0.4x as long as dactyl body; propus 1.9x longer than wide palm with 2 long simple distal setae, 3 medial stout setae and 2 proximal stout setae, proximalmost setae smooth, distalmost proximal seta and all medial setae serrate, distalmost medial setae with small basal tooth. Pereopods 2-5 coxae rounded, not produced, with simple anterior seta. Pereonites 2-4 longer but narrower than pereonite 1 with well-developed tergal plates, medial suture faint or not apparent, with 1 long simple anterolateral seta and an anterior fringe of short simple setae. Pereopods 2-4 inserted anterodorsally; dactylus long, about 2x longer than wide, 2-clawed, claws robust, one shorter and angulate; propus subcylindrical with 2-3 short simple distal setae; carpus long with 1 short simple setae; merus short with 0-3 simple setae; ischium long, subcylindrical. Pereonites 2-3 subequal in length. Pereopods 2-3 basis with 1 simple and 1 long plumose setae. Pereonite 2 0.9x as wide as long, wider than pereonite 3. Pereopods 3-4 carpus with a small claw-like spine. Pereonite 4 longer and wider than pereonites 2-3. Pereopod 4 basis with 4 simple setae. Pereonites 5-7 lacking setae, larger than pereonites 2-4, with distinct lateral tergites. Pereopods 5-7 inserted posterodorsally; dactyl, propus and carpus subsimilar to those on pereopods 2-4; merus short with 0-1 simple setae; ischium with 0-1 short simple setae; basis with 2-3 simple setae. Pereopods 5-6 ischium longer and slenderer than on pereopod 7. Pereonite 5 subequal in length as pereonite 7. Pereonite 6 1.3-1.4x longer than pereonites 5 and 7. Pereopod 6 dactyl with 1 pair of small distolateral teeth; propus with distolateral row of short simple setae. Pereonite 7 about as wide as long. Pleonites 1-2 subequal, about 1.7x wider than long, with simple tergites and without lateral setae. ♂ pleopod 2 protpod rectangular, 0.6x as wide as long; exopod about 2x longer than wide tapering to a rounded tip, apical seta about as long as exopod body; endopod 1.5x longer than protopod, 0.7x as long as telson, not reaching tip of telson, straight, triangular, tapering distally to a large stout subapical seta and an apical cluster of short simple setae. Pleopods 3-4 flat, slightly rippled. Pleopod 3 not noticeably biramous, with 1 simple seta. Pleopod 4 lacking setae; rami subequal in length. Telson about as wide as long, 1.7x longer than pleonite 2; lateral margins parallel with 1 pair of setae; tip subtrapezoidal, laterally slightly concave. Uropod protopod rectangular, about as wide as long, distally curved with 2 long simple setae; exopod 0.3x as long as endopod with 1 long apical setae nearly reaching distal third of endopod; endopod long, parallel-sided, tapering distally, 1.9x longer than protopod, with 3 long and 1 short distal setae, 1 long subapical seta and 2 shorter lateral setae.
Geographic Range: Known from a series of springs and wells in Hays and Travis Cos., Texas that originat from the Edwards Aquifer (specifically the San Antonio and Barton Springs Pools).
Notes: This species is most similar to T. amistad, see that species account for more information.

Sources

Hutchins, B. T., Schwartz, B. F. & Coleman, W. T. (2021). Three new microcerberids (Isopoda: Microcerberidae) from subterranean freshwater habitats in Texas, USA. Journal of Natural History, 55(35-36):2261-2278.

Published: Feb 15, 2023