Cirolanides wassenichae, Schwartz & Hutchins & Schwartz & Hess & Bonett, 2019

Schwartz, Benjamin F., Hutchins, Benjamin T., Schwartz, Zachary G., Hess, Alexander J. & Bonett, Ronald M., 2019, Cirolanides wassenichae sp. nov., a freshwater, subterranean Cirolanidae (Isopoda, Cymothoida) with additional records of other species from Texas, United States, Zootaxa 4543 (4), pp. 498-514 : 502-509

Cirolanides wassenichae sp. nov.

Figs 2–6

Material examined. Holotype: ♀ (11.3 mm), EARDC Cat #: AW 130305 -1, USNM 1480594 San Marcos Artesian Well ( SMAW), Hays County, Texas, U.S.A.: 29.88963°N, 99.9364°W, ~177mASL, 25 March 2013, coll. B. Hutchins, B. Schwartz, and Z. Schwartz.

Paratypes: ♂ (10.2 mm), EARDC Cat #: AW 111026 -1, USNM 1480595 San Marcos Artesian Well ( SMAW), Hays County, Texas, U.S. A, 29.88963°N, 99.9364°W, ~ 177 m ASL, 26 October 2011 , coll. unknown—identified in 2018 from EARDC archived samples. USNM 1480596 and 1480597, Panther Canyon Well , Comal County, Texas, U.S.A.: 29.71361°N, 98.13830°W, ~ 204 m ASL, 30 September 2014 , and 23 September 2015, coll. Randy J. Gibson.

Additional material. (Note: most juveniles were sacrificed for molecular analysis. For most mature specimens, one set of pereopods was used for molecular analysis. EARDC catalog numbers are provided for archived specimens) TEXAS, USA: COMAL CO., Comal Springs , Spring # 3 (29.71352°N, 98.1371°W), coll. R. Gibson , 27 Oct., 2016, 2 juv.; Comal Springs , Spring #7 (29.71533°N, 98.1349°W), coll. R. Gibson , 28 Oct., 2016, 1 ♂ ( EARDC Cat #: CS7 161028 -1) ; Panther Canyon Well (29.71361°N, 98.1383°W), coll. R. Gibson , 24 Jul., 2015, 1 ♂, 1 ♀ ( EARDC Cat #: PC 150725 -1, PC 150725 -1) ; Mission Valley Bowling Well (29.72056°N, 98.1794°W), coll. R. Gibson , 7 Jun., 2013, 1 ♀ ( EARDC Cat #: MV 130607 -1 ) ; HAYS CO., San Marcos Artesian Well (29.88963°N, 97.9364°W) (paratypes, coll. B. F. Schwartz, B. T. Hutchins, A. P. Swink, V. Castillo III) , 8 May, 1976, 1 ♀; 14 Feb., 2013, 1 ♂; 18 Feb., 2013, 1juv.; 26 Mar., 2013, 1juv.; 28 Mar., 2013, 1juv.; 15 Nov., 2013, 1 ♂, 1 juv.; 19 Nov., 2013 1 juv.; 22 Nov., 2013, 1juv.; 29 Nov., 2013, 1 juv.; 2 Dec., 2013, 1 juv.; 5 Dec., 2013, 1 juv.; 12 Dec., 2013, 1 juv.; 19 Feb., 2014, 1 ♂, 1 juv.; 14 Jul., 2014, 1 ♀; 16 Jun., 2015, 2 ♀; 3 Jul., 2015, 1 ♀; 17 Aug., 2015, 1 ♀; 6 Sep., 2017, 1 ♂, ( EARDC Cat. #s: AW 130214 -1, AW 131115 -2, AW 140219 -1, AW 150616 -1, AW 150616 -2, AW 150703 -1, AW 150817 -1, AW 170906 -1, AW 760508-1 ) ; San Marcos Springs , Deep Hole Spring (29.89237°N, 97.9323°W), coll. G. Longley , 15 Nov., 1976 ( EARDC Cat #: DH 761115-1), 1 juv. ; Ezell’s Cave , coll. J. Krejca , 1 Jun., 2006, 1 ♂; Spring Lake Outflow Well (29.89292°N, 97.93143°W), coll. A. Everett , 24 Jul., 2017, 1 juv ( EARDC Cat #: SLO 170724 -1 ); UVALDE CO., Bill Stockton well (29.2002°N, 99.844°W) (identified by R. C. Wiedenfeld as C. texensis ), coll. R. C. Wiedenfeld , 1 May, 1980, 1 damaged ( EARDC Cat #: BSW 800501-1 ); R. K. Dunbar Farm Well (29.23139°N, 99.8614°W) (identified by R. C. Wiedenfeld as C. texensis ), coll. R. C. Wiedenfeld , 10 Jun., 1980, 1 ♂ ( EARDC Cat #: RKD 800610-1 ) . All specimens curated at Texas State University Edwards Aquifer Research and Data Center ( EARDC) except for Ezell’s Cave (University of Texas Austin, Biodiversity Center Collections) and type material, discussed above .

Diagnosis: Antenna reaching pereonite 5, flagellum composed of 20 articles; frontal lamina narrow, extending to distal margin of antennula peduncle article 1; pereopods 1-2 haptorial, pereopod 3 intermediate between haptorial and ambulatory; posterior margin of pleotelson quadrate, lateral margins parallel, posterior margin medially concave; distomedial angle of uropodal protopod more acutely produced than in C. texensis , extending to middle of pleotelson, exopod and endopod subequal in length, extending to posterior margin of pleotelson.

Description of holotype female: Body 11.3 mm long, without pigment, 2.7 times as long as greatest width, widest at pereonite 4, lateral margins parallel ( Figs 2–5 ); pereonite 1 and coxae 2 with posteroventral angle rounded, coxae 3–7 with acute posteroventral angle and single, entire oblique carina, ( Fig. 2 ); pereonite 7 with anterior internal concave ‘suture’ ( Fig. 2 ); pleonites 1–5 with posteroventral angles acute, not concealed by pereonite 7 which extends 2/3rds length of first pleonite ( Fig. 2 ); pleotelson quadrate, 0.8 times as wide as long, lateral margins parallel, posterior margin with medial concavity ( Fig. 2 ), cephalon trapezoidal, deeply inserted into pereonite 1, 1.6 times as long as greatest width, anterior margin rounded, posterior margin weakly concave with sparse fringe of short, simple setae ( Fig. 2 ); eyes absent.

Antennula extending to middle of pereonite 1, peduncle articles 1 and 2 subequal in length, approximately 5 times length of article 3, peduncle articles with 3 or 4 plumose setae, flagellum with 6 articles, each with 1–3 pappose setae ( Fig. 3 ); antenna extending to pereonite 5, peduncle articles 1 vestigial, 2 reduced, 3 and 4 subequal in length, approximately half as long as article 5, peduncle article 5 slightly shorter than 6, articles 5 and 6 with 2– 3 plumose setae and 2–6 short, simple setae, flagellum with 20 articles subequal in length with clusters of 3–5 short simple setae near distal ends, pappose setae lacking.

Frontal lamina narrow, extending to distal margin of antennule peduncle article 1 ( Figs 2 , 3 ); clypeus transversely rectangular, concave posterior margin with sparse fringe of short simple setae ( Fig. 3 ); labrum directed ventrally, rectangular, with dorsomedial margin produced anteriorly ( Fig. 3 ).

Left mandible molar process anteriorly with 24 sharp to peg-shaped teeth, distally with tiny finger-like process; lacinia mobilis with approximately 14 curved spiniform setae; incisor hyaline, with jagged cutting surface, cusps indistinct, dorsal margin produced as rounded lobe; palp segment 2 approximately two times as long as segment 1 or 3, with 6 short and 3 long serrate setae, 6 short spiniform setae distally; palp segment 3 approximately 2.5 times as long as wide, tapering distally, with approximately 26 serrate setae ( Fig. 3 ). Right mandible molar process similar to left mandible; lacinia mobilis with 12 curved spiniform setae; incisor hyaline, with 3 cusps decreasing in size dorsally; palp similar to left mandible but segment 2 with 12 serrate setae, segment 3 with 20 serrate setae ( Fig. 3 ). Maxillula endopod with 3 large, circumplumose setae, 2 small, simple setae, exopod with 8 robust serrate and 4 robust cuspidate setae ( Fig. 3 ). Maxilla basis with 1 simple seta distally; lateral and medial lobes subequal in length, with 4 and 7 long, serrate setae, respectively; mesial lobe with 13 long, serrate setae distally, 1 simple setae near articulation with medial lobe, patch of small, simple setae distomedially ( Fig. 3 ). Maxilliped endite with 2 coupling hooks, 5 long, plumose setae; palp articles 2 and 3 with well-developed lobes mesially, article 1 with 2 plumose setae on lateral margin and 4 plumose setae on mesial margin, article 2 with 6 plumose setae on lateral margin and 14 plumose setae on mesial margin, article 3 with 3 plumose setae on lateral margin and 13 plumose setae on distomesial lobe, article 4 with 3 plumose setae on lateral margin and 12 plumose setae distally ( Fig. 3 ).

Pereopod 1 ( Fig. 4 ) robust, haptorial; basis subequal in length to propodus, rectangular, with 1 plumose seta at base, and few short, simple setae; ischium triangular, sub equal in length to merus and carpus, with row of 3–6 short spiniform setae on ventral margin; merus short, rectangular, with 2 pairs of robust spiniform setae and 1 simple seta on ventral margin; carpus with 1 spiniform seta and 2 simple setae on distal, ventral corner; propodus length to width ratio 1.6:1, palmar margin straight with 3 large serrations corresponding to bases of 3 robust spiniform setae with rasp-like tips; dactylus simple with spiniform seta at base of unguis.

Pereopod 2 ( Fig. 4 ); haptorial but not as robust as P1; basis rectangular, with short simple setae; ischium triangular, with robust spiniform seta on ventral and dorsal disto-apical corners; merus rectangular, subequal in length to ischium with 8–9 robust spiniform seta on ventral margin and dorsal-apical corner; carpus rectangular, slightly shorter than merus, with 6 robust spiniform seta on ventral margin and ventral-distal corner; propodus subrectangular, length to width ratio 2.6:1, palmar margin straight with 4 robust spiniform setae, distal-most tooth serrate or rasp-like, remaining simple, all 4 with simple accessory setae, single plumose seta near anterior-distal corner; dactylus simple, curved, with spiniform setae at base of unguis.

Pereopod 3 ( Fig. 4 ) slightly haptorial, but not as strongly as P1–2; basis rectangular, with short simple setae and 1 plumose seta near mid-anterior margin; ischium triangular, subequal in length to merus, with 3 robust spiniform seta on distal-apical margin; merus quadrate, slightly longer than carpus, with 4 robust spiniform seta ventrally, 7 robust spiniform seta on distal-apical margin; carpus rectangular with pair of robust spiniform seta on ventral margin, 5–7 on apical margin; propodus length to width ratio 3.0:1, ventral margin straight with 4 robust spiniform seta (first 3 serrate, distal-most rasp-like), additional short spiniform setae on ventral surface; dactylus simple, curved, with 1 or 2 spiniform setae at base of unguis.

Pereopod 4 ( Fig. 4 ) ambulatory; basis elongate, rectangular, 2 plumose setae on posterior margin, short simple setae on posterior and anterior margins; ischium narrowly triangular, stout spiniform setae on distal margin; merus quadrate with stout spiniform setae on distal and posterior margins; carpus quadrate with stout, simple and denticulate spiniform setae on distal and posterior margins; propodus narrow, 3 simple setae and 1 plumose seta on distal margin, posterior margin with 3 pairs of stout spiniform setae, single spiniform seta near anterior end, with 4 pairs of stout spiniform setae on margin; dactylus simple, curved, with 1 or 2 spiniform setae at base of unguis.

Pereopod 5 ( Fig. 4 ) ambulatory; basis elongate, rectangular, 2 plumose setae on posterior margin, short simple setae on posterior and anterior margins; ischium narrowly triangular, stout spiniform setae on distal margin, 2 spiniform setae on posterior margin; merus quadrate with spiniform setae on distal margin, 1 denticulate and 1 spiniform seta on posterior margin; carpus narrow, quadrate, 2 pairs of spiniform setae on posterior margin, stout spiniform setae on distal margins; propodus narrow, rectangular, 3 simple setae and 1 plumose seta on distal margin, posterior margin with 2 pairs of stout spiniform setae, additional single spiniform seta near anterior end between 2 spiniform seta pairs, with 4 pairs of stout spiniform setae on margin; dactylus simple, curved, with 1 to 2 spiniform setae at base of unguis.

Pereopod 6 ( Fig. 4 ) ambulatory; basis sub-rectangular, 3 plumose setae on anterior margin, short simple setae on posterior anterior and distal margins; ischium narrowly triangular, stout spiniform setae on distal margin, 4 spiniform setae on posterior margin; merus rectangular, 2 simple and 1 denticulate spiniform setae on posterior margin, a cluster of robust simple and 1 denticulate spiniform setae on distal end; carpus narrow, quadrate, 3 pairs of spiniform setae on posterior margin, stout spiniform setae and 2 denticulate spiniform setae on distal margins with 1 plumose setae near distal end; propodus narrow, rectangular, 4 simple and 1 plumose setae on distal margin, posterior margin with 1 pair of stout spiniform setae and 3 single stout spiniform setae, with 4 pairs of stout spiniform setae on margin; dactylus simple, curved, with 1 or 2 accessory spiniform setae at base of unguis.

Pereopod 7 ( Fig. 4 ) ambulatory; basis with 2 plumose setae on anterior margin, short simple setae on posterior and anterior margins; ischium narrow, rectangular, with 4 short simple setae on posterior margin, robust simple and denticulate spiniform setae on distal margin; merus rectangular, 3 spiniform setae on posterior margin, robust simple and 1 denticulate spiniform seta on distal margin; carpus narrow, quadrate, 2 pairs of stout spiniform setae on posterior margin, stout spiniform setae and 3 denticulate spiniform setae on distal margin with 1 plumose setae near distal end; propodus narrow, rectangular, 4 simple setae and 1 plumose seta on distal margin; posterior margin with 2 pairs of stout spiniform setae and 3 stout single spiniform setae, with 5 pairs of stout spiniform setae on margin; dactylus simple, curved, with 1 or 2 accessory spiniform setae at base of unguis.

Pleopod 1 protopod with 7 coupling hooks ( Fig. 5 ); endopod 3.7 times as long as wide, lateral margin slightly concave, mesial margin nearly straight, rounded distally, with 30 plumose setae on distal margin, no suture; exopod trapezoidal, 1.6 times as long as wide, 62–66 plumose setae on distal margin, 1 setae proximally on lateral margin, no suture. Pleopod 2 protopod with 7 coupling hooks ( Fig. 5 ); endopod 2.6 times as long as wide, lateral margin slightly concave, mesial margin straight, rounded distally, with 23 plumose setae on distal margin, no suture; exopod trapezoidal, 1.6 times as long as wide, 60 plumose setae distal to transverse margin, 2 plumose setae on lateral margin proximal to suture. Pleopod 3 protopod with 7 coupling hooks ( Fig. 5 ); endopod 1.9 times as long as wide, ovate, with proximal transverse suture; exopod quadrate, 1.4 times as long as wide, 49 plumose setae distal to transverse suture, 3 plumose setae on lateral margin proximal to suture. Pleopod 4 protopod with 7 coupling hooks ( Fig. 5 ); endopod 1.7 times as long as wide, ovate, with proximal transverse suture; exopod ovate, 1.4 times as long as wide, 42 plumose setae distal to transverse suture, 4 plumose setae on lateral margin proximal to suture. Pleopod 5 peduncle without coupling hooks, 1 setae on lateral margin ( Fig. 5 ); endopod 1.5 times as long as wide, sub-ovate with proximal transverse suture; exopod ovate, 1.3 times as long as wide, with 14 plumose setae distal to oblique suture, with 5 plumose setae on lateral margin proximal to suture.

Uropod protopod triangular ( Fig. 5 ), produced as an acute point distomedially, slightly longer than wide, extending to middle of pleotelson and proximal fourth of exopod, 6 plumose setae distomedially, 2 lanceolate setae distolaterally; endopod broadly lanceolate, 1.6 times as long as wide, 11 plumose setae on medial margin, 5 plumose setae on lateral margin, 14 robust simple and plumose setae distally; exopod narrowly lanceolate, 3 times as long as wide, 7 simple setae on lateral margin, 4 simple setae distally.

Male. Slightly larger than female. Pereopod 1–7, pleopods 1–5 (except pleopod 2), habitus, uropod, antenna, and antennula ( Fig. 6 ) as in females. Pleopod 2 ( Fig. 6 ): appendix masculina smooth, curved, 1.3x as long as endopod, end narrowly rounded distally; inserted distally from base of endopod (~20% of length, from base); exopod ovate, 1.4 times as long as wide, 47 plumose setae on distal margin, distal to transverse suture, 1 plumose setae on lateral margin proximal to suture; endopod 2.4 times as long as wide, 21 plumose setae on distal margin; 1 circumplumose seta and 6 coupling hooks on protopod; this contrasts with 7 coupling hooks on female pleopod 2. Penial processes ( Fig. 2 ): flat, thin, paddle-shaped with slight indentations in squared distal ends, tapering slightly distally, 2.3x longer than wide, centerline of processes separated by 15% width of sternite 7 ( Fig. 2 ).

Size and morphological differences. Mature male C. wassenichae sp. nov. (mean = 9.5 mm, range = 8.4–10.7 mm) are slightly larger than mature females (mean = 8.8 mm range = 5.3–12.3 mm). Additionally, C. wassenichae sp. nov. is slightly smaller than mature C. texensis males (mean length = 11.1 mm, range = 7.4–12.4 mm) and females (mean length = 10.4 mm, range = 5.5–16.4 mm). Across all body sizes, C. wassenichae sp. nov. consistently has ~35% as many flagellar segments on A1 and A2 as C. texensis ( Fig. 7 ). There are no differences in relationships between body size and number of flagellar segments between sexes in either species.

Etymology. The species epithet wassenichae honors Mrs. Dianne Wassenich, Program Director of the San Marcos River Foundation (SMRF) and long-time advocate for San Marcos River and Edwards Aquifer conservation. We advocate adoption of the common name, Wassenich’s isopod.

Genetics. The Co1 phylogeny (see Fig. 8 ) recovered two deeply divergent lineages within Cirolanides (0.117 ± 0.0061 uncorrected p; see Table 2). One lineage corresponds to described morphologies of C. texensis ; the other corresponds to the new species, C. wassenichae sp. nov. Despite deep divergence between lineages, within lineage divergence was shallow ( C. texensis 0.002 ± 0.0042 uncorrected p, C. wassenichae sp. nov. 0.0058 ± 0.0039 uncorrected p). 28S displayed a similar pattern of divergence, with higher levels of between-lineage divergence (0.0097 ± 0.0016 uncorrected p) than within-lineage ( C. texensis : 0.002 ± 0.0024 uncorrected p; C. wassenichae sp. nov.: 0.00017 ± 0.00061 uncorrected p). Both nuclear and mitochondrial phylogenies showed strong posterior support values for two clades within Cirolanides ( C. texensis , C. wassenichae sp. nov.; Fig. 8 ). Divergence was higher for mitochondrial than nuclear genes, which is expected ( Brown et al. 1979).

Distribution. The type locality, known for stygobiotic diversity, is a well completed in the confined zone in a relatively shallow portion of the San Antonio Pool of the Edwards Aquifer. At 59.5 m depth, the well intersects a 1.5 m tall conduit ( Holsinger & Longley 1980), from which the water and biological materials are presumed to discharge. Water quality is high and has been dye-traced to San Marcos Springs, less than 1 km to the northeast (see details in Ogden et al. 1986). In November 2013, water temperature at the well averaged 22.3°C (SD +0.01), dissolved oxygen averaged 5.3 mg /L (SD +0.01), and electrical conductivity averaged 608 µS/cm (SD +0.50). Cirolanides wassenichae sp. nov. is known from nine sites, in addition to the type locality ( Table 3). All sites are springs, caves, or wells that intersect the phreatic zone of the karstic Edwards Aquifer, in a narrow 200 km long band that parallels the Balcones Escarpment in central Texas ( Fig. 1 ). The new species is sympatric with C. texensis at seven sites ( Table 3).

Remarks. Cirolanides wassenichae sp. nov. differs from the current diagnosis of the genus in that the 2 nd pereopod is haptorial and not ambulatory and the 3 rd pereopod is intermediate between ambulatory and haptorial rather than ambulatory. As discussed below, however, a generic revision is premature at this time. Cirolanides wassenichae sp. nov. is readily distinguished from C. texensis by the following features: smaller size (see statistics above), flagellum of antennula with fewer articles (3–5 vs. 9–15); flagellum of antenna with fewer articles (12–21 vs. 21–39); pereopod 2 haptorial vs. ambulatory; pereopod 3 semi-haptorial vs. ambulatory; pereopod 1 longer than pereopods 2 and 3 (which are subequal in length) vs. pereopod 1 shorter than pereopods 2–3 in C. texensis ; body more slender with lateral margins nearly parallel vs. ovate; posterior margin of pleotelson truncate with medial concavity vs. well-rounded; uropod endopod wider and overlapping exopod more; uropod endopod and exopod shorter and extending only slightly past posterior margin of pleotelson vs. well past.

Figures

FIGURE 1. Range map for Cirolanides and Speocirolana hardeni in Texas and Mexico. Cirolanides wassenichae sp. nov. = large red circles; C. wassenichae sp. nov. and C. texensis = large red squares; C. texensis = small black triangles; Speocirolana hardeni = small purple triangles; C. texensis and S. hardeni = small orange triangles; C. texensis mexicensis = black diamonds.

FIGURE 2. ♂ (10.2 mm): A, habitus dorsal; D, sternite 7 and penial processes; ♀ (11.3 mm): B, habitus dorsal; C, habitus lateral

FIGURE 3. ♀ (11.3 mm): A, antenna; B, antennula; C, clypeus; D, left mandible; E, right mandible; F, left maxillula 1; G, left maxilla 2; H, left maxilliped.

FIGURE 4. ♀ (11.3 mm): A–G, pereopods 1–7.

FIGURE 5. ♀ (11.3 mm): A–E, pleopods 1–5; F, uropod.

FIGURE 6. ♂ (10.2 mm): A, pleopod 1; B, pleopod 2; C, uropod; D, pereopod 1; E, antenna; F, antennula.

FIGURE 7. Relationships between body length and flagellar segments Cirolanides wassenichae sp. nov. and Cirolanides texensis. Red symbols = C. wassenichae sp. nov. Blue symbols = C. texensis. Open symbols = Male; filled symbols = Female. Squares and circles = A1; circles and triangles = A2.

FIGURE 8. Genetic divergence between Cirolanides texensis (blue) and Cirolanides wassenichae sp. nov. (red) based on 28S (A) and Co1 (B).