Caecidotea beattyi

Caecidotea beattyi

Caecidotea sp. no. 3 Peck and Lewis, 1978:44.

MATERIAL EXAMINED.—ILLINOIS. Pope Co.: Dixon Springs State Park, runoff stream from wellhouse, leg. Julian J. Lewis, 8 Apr 1975 (4.7 mm ovig. paratype, USNM 171184) and 17 Jul 1976 (3, 4.1, 4.5, 6.5 mm; 2, 3.2, 10.1 mm). The 10.1 mm is the holotype (USNM 172789); the other specimens are paratypes (USNM 172790). Champaign Co.: Upper Salt Fork, 2 mi (3.2 km) SE Rantoul, 25 Jun 1975, leg. W. Ettinger, 1 (INHS). Fayette Co.: Farina, Kaskaskia Drive, well, leg. Bob Britton, 12 Sep 1977, 1, pereonites with slight pigmentation (INHS). Iroquois Co.: tributary of Iroquois River, 3 mi (4.8 km) W Pittwood, 17 Sep 1975, leg. J. A. Boyd and L. M. Page, 3, 1 (INHS). Massac Co.: Main Ditch, 1 mi (1.6 km) NE Mermet, 27 Apr 1976, leg. J. A. Boyd and L. M. Page, 18, 35 (18 ovig.) (INHS). MISSOURI. St. Louis Co.: spring on Kiefer Creek, 0.6 mi (.97 km) NW Fern Glen, 22 Mar 1942, leg. L. Hubricht, 7, 25 (USNM). Castlewood, seep, 13 Apr 1942, leg. L. Hubricht, 4 (USNM).

DESCRIPTION.—A medium-sized species, eyeless, slightly pigmented. Length up to at least 11.5 mm; body slender, linear, about 7.7× as long as wide in holotype, about 4.7× as long as wide in ovigerous . Pereonites 1–3 of ovigerous slightly expanded in dorsal aspect; coxae visible in dorsal view. Margin of head only slightly setose, margins of pereonites and telson moderately setose. Head about 1.3× as wide as long, anterior margin slightly concave, postmandibular lobes slightly produced. Telson about 1.5× as long as wide, posterior margin convex, caudomedial lobe low and broad, not obviously developed. Dorsal surface of head and pereonites with very fine scattered purple pigment, apparently less noticeable with maturity.

Antenna 1 reaching almost to end of last segment of antenna 2 peduncle; flagellum of about 7–10 segments, esthete formula 3–0–0 or 4–0–0. Antenna 2 reaching from pereonite 7 to middle of telson; last segment of peduncle about 1.4× length of preceding segment; flagellum with up to 54 segments.

Mandibles with 4-cuspate incisors and lacinia mobilis; spine-row of 10 spines (left) or 12 spines (right); palp with 2 large apical spines. Maxilla 1, apex of outer lobe with 13 large spines and 2 setae, 1 subterminal, 1 medial; inner lobe with 5 apical setae, variously plumose. Maxilliped with 6 retinacula on right, 5 on left; outer lobe with about 11 lateral spines.

Male pereopod 1 propus about 1.4× as long as wide; palm concave, with stout articulated triangular proximal process and broad bidentate distal process. Dactyl flexor margin with proximal rounded boss, small mesial process, 4 very weak spines. Female pereopod 1 more slender, propus about 1.7× as long as wide; palm with 1 large proximal spine and 1 robust seta; dactyl flexor margin with smaller boss, mesial process lacking, 4 mesial spine teeth in row. Pereopod 4 more spinose in male than female, carpus more robust in male, 1 mesial spine on dactyl of female, 2 in male.

Male pleopod 1 larger than pleopod 2; protopod about 0.7× length of exopod, with 9 retinacula on both sides; exopod about 0.6× as wide as long, lateral margin distinctly S-shaped, proximal convex part bearing 8 long setae; distal concave part bearing 10 setae decreasing in length distally; distolateral lobe serrulate. Male pleopod 2, proximal segment of exopod with 1 short seta proximally and 5–6 longer plumose setae distally; distal segment of exopod triangular, with 7 medial and distal plumose setae and 10 lateral nonplumose setae, with row of spinules at base of row of nonplumose setae. Endopod slender, curving laterally, ending in conspicuous conical cannula and shorter, more slender sigmoid lateral process, both directed subparallel to axis of endopod, the 2 processes separated by an angle of about 30°. Female pleopod 2 exopod oval, about 2× as long as wide; lateral margin with 12 plumose setae. Male pleopod 3 exopod about 1.8× as long as wide, with 11 distal plumose setae; distal segment about 2.2× length of proximal segment. Pleopod 4 with B pattern, without proximal spines.

Male uropods distinctly spatulate, triangular in cross section; female uropods similar, shorter, and more cylindrical in cross section. Male protopod about 1.1× length of endopod, 4.2× length of exopod; female protopod about 1.1× length of endopod, 1.9× length of exopod.

ETYMOLOGY.—The new species is named for Dr. Joseph A. Beatty, Southern Illinois University, in gratitude for his encouraging JJL's studies of the subterranean fauna of Illinois.

RELATIONSHIPS.—Caecidotea beattyi is closest morphologically to C. antricola from caves in Missouri and Arkansas, described above. The pleopod 2 and gnathopod are similar in the 2 species, but the proximal process of the gnathopod palm is larger in C. beattyi. Caecidotea antricola lacks the concave lateral margin and serrulate distolateral lobe of pleopod 1, characteristic of C. beattyi. In C. beattyi the cannula and lateral process of pleopod 2 are terminal, and no caudal process is present; in C. antricola the apex of the endopod forms a caudal process behind the subterminal cannula and lateral process.

Caecidotea beattyi is lightly pigmented, whereas C. antricola is unpigmented. This difference is correlated with the different habitats of the 2 species; C. antricola is confined to caves, but C. beattyi appears to be a phreatobite, sometimes occurring above ground.

HABITAT.—The type-locality is a small runoff stream issuing from what is apparently a well or spring, covered by a gazebo (Figures 11f, 12d). A permanent metal cover conceals the source of the water. The runoff from the pipe extending out of the gazebo flows a few feet into a small stream that flows along a sandstone bluff through picnic grounds in the state park.

The well, ditch, and stream collections suggest that C. beattyi is a phreatobite inhabiting shallow groundwater, from which it is occasionally discharged. At the Massac Co. locality several drain tiles empty into Main Ditch at the site where C. beattyi was taken.

RANGE.—Caecidotea beattyi is generally distributed through the basin of the Wabash River, although it is not restricted to this drainage (Figure 1). This species has penetrated far into the glaciated region, the Iroquois Co. population living about 257 km (160 mi) from the closest Illinoian glacial boundary and 145 km (90 mi) from the Wisconsinan boundary. Willman and Frye (1970) discuss the stratigraphy of the unconsolidated deposits (till, outwash, alluvium) present over C. beattyi's range.

Caecidotea beattyi occurs primarily within the Central Lowlands Province, but also has been taken from the Shawnee Hills Section of the Interior Low Plateaus Province and the northern margin of the Coastal Plain Province. According to the physiographic divisions illustrated by Willman et al. (1975, after Leighton et al., 1948), the Massac Co. population apparently falls within the southern part of the Shawnee Hills Section. A more precise analysis using the natural divisions of Schwegman (1973) places this locality within the Bottomlands Section of the Coastal Plain Province.

MATERIAL EXAMINED.—ILLINOIS. Bureau Co.: 0.5 mi (0.8 km) E Lone Tree, in ditch by drain tile outlet, leg. Larry M. Page (LMP) and James A. Boyd (JAB), 12 Jul 1974, 3, 9 (INHS). Carroll Co.: Smith Park Cave, 1 mi (1.6 km) W Mt. Carroll, leg. S. Peck, 1 Nov 1965, 4, 2. Champaign Co.: 2 mi (3.2 km) NW Rantoul, drain outlet, leg. M. A. Morris, 2 Feb 1975, 8, 2 (INHS). 3 mi (4.8 km) N Mayview (type-locality), drain outlet, leg. CWR and LMP, 9 Jun 1974, 1 (INHS); same locality, leg. J. J. Lewis (JJL), 21 Jul 1976, 17, 7 (USNM). 1 mi (1.6 km) SW Thomasboro, Saline Branch, leg. M. Wetzel, 1 Apr 1974, 1 (INHS). Champaign, drain tile, leg. AJS, no date, 9, 1 (USNM 278862). Champaign, ditches, leg. HHR and Burks, 21 Mar 1939, 2 (INHS); 107 E. Bell Fountain Ave., open well, leg. L. A. Dailey, 5 Jun 1939, 1, 1 (INHS). 1 mi (1.6 km) E Bondville, tile outlet, Kaskaskia River, leg. LMP, 24 May 1974, 8, 2 (INHS). 1 mi (1.6 km) S Urbana, end of drain tile, leg. HHR, 13 Feb 1932, 2 (INHS). Seymour, leg. T. H. Frison and HHR, 27 May 1929, 5, 1 (INHS). Sherrard, leg. Dan Zwicker, 12 Feb 1938, 3, 2 (INHS). Urbana, N Crystal Lake in sinkhole, leg. HHR, 13 Feb 1932, 1 (INHS). Savoy, leg. C. O. Mohr, 6 May 1936, 29, 5 (INHS). Seymour, leg. T. H. Frisson and HHR, 22 Mar 1930, 10, 7 (INHS). Urbana, leg. HHR, 16 Feb 1932, 1 (INHS); Urbana, R. R. Parks, Jun 1939, 1, 2 (INHS). Savoy, drainage ditch, leg. H. J. Van-Cleave, 9 May 1942, 5 (USNM 108592). Christian Co.: Spring Creek, 4 mi (6.4 km) E Taylorville, leg. LMP and JAB, 6 Aug 1975, 1 (INHS). Coles Co.: Greasy Creek, muddy stream, 2 mi (3.2 km) W Bushton, leg. LMP and CWR, 23 Mar 1975, 2, 2 (INHS). Cook Co.: 2 mi (3.2 km) S Lansing, outlet of drain, leg. Leslie Hubricht (LH), 21 Apr 1942, 73 (USNM 108609). Dewitt Co.: 1 mi (1.6 km) N Weldon, Friend Creek ditch, tile outlet, leg. LMP, 24 May 1974, 1, 1 (INHS). Weldon Spring State Park, covered spring, in milk carton, leg S. Peck, 16 May 1966, 1, 1. Edgar Co.: Catfish Creek, 0.5 mi (0.8 km) S Mays, Leg. LMP, 16 Oct 1974, 2, 6 (INHS). Fulton Co.: 1.4 mi (2.3 km) S Avon, outlet of drain, leg. LH, 4 May 1941, 47 (USNM 108583). Hancock Co.: Wildcat Cave stream, 1 mi (1.6 km) N Hamilton, leg. LH, 25 Apr 1942, 11 (USNM 108596). Wildcat Springs, spring and cave above creek, 0.5 mi (0.8 km) N Hamilton, leg. LMP and R. Evers, 14 May 1975, 3, 3 (INHS). Henderson Co.: 3 mi (4.8 km) E Biggsville, outlet of drain, leg. LH, 25 Apr 1942, 20 (USNM 108595). 1.7 mi (2.7 km) W Biggsville, outlet of drain, leg. LH, 25 Apr 1942, 17 (USNM 108598). Henry Co.: Atkinson, in well, leg. H. D. Allison, Apr 1942, 1 (INHS). Iroquois Co.: Coon Creek (Iroquois Drive), 2 mi (3.2 km) S Darrow, leg. LMP and L. Cordes, 10 Sep 1977, 2 (INHS). Prairie Creek, 0.5 mi (0.8 km) N L'Erable, leg. JAB and LMP, 17 Sep 1975, 2, 1 (INHS). Pigeon Creek, Cissna Park, leg. B. M. Burr and JAB, 13 Nov 1975, 2, 1 (INHS). Kane Co.: Coon Creek, 1.5 mi WSW Hampshire, field tile, leg. W. Vinikour and R. Anderson, 1 May 1975, 2 (INHS). Kankakee Co.: Wiley Creek at IL Highway 113, 5.1 mi (8.2 km) NW center of Kankakee, leg. J. Clamp, 11 May 1978, 6 (NCSM C125). Knox Co.: 5.1 mi (8.2 km) N St. Augustine, outlet of drain, leg. LH, 4 May 1941, 70 (USNM 108580). 2.0 mi (3.2 km) N Abingdon, outlet of drain, leg. LH, 4 May 1941, 2 (USNM 108579). 1.6 mi (2.6 km) SW Galesburg, leg. LH, 4 May 1941, 2 (USNM 108582). LaSalle Co.: just N Peru, Gustave Engelhaupt Farm, outlet of drain, leg. LH, 3 May 1941, 250 (USNM 108852). Macon Co.: Long Point Slough, 1.5 mi (2.1 km) N Niantic, leg. LMP and JAB, 26 Aug 1975, 2 (INHS). McClean Co.: 4 mi (6.4 km) SE Heyworth, tributary Long Point Creek, large drain outlet, 24 May 1974, 15, 20 (INHS). McDonough Co.: 4.8 mi (7.7 km) N Macomb, outlet of drain, leg. LH, 4 May 1941, 930 (USNM 108851). 5.9 mi (9.5 km) N Macomb, outlet of drain, leg. LH, 4 May 1941, 68 (USNM 108584). Knox Co.: drain tile, 1.5 mi N Abingdon, leg. JJL, 24 Jul 1976, 2, 1. Ogle Co.: Pines Park [= White Pines State Park?], leg. Frison and Ross, 9 Dec 1932, 7, 7 (INHS). Peoria Co.: Rocky Glen, leg. Burks and Riegel, 17 Apr 1939, 1 (INHS). 1.5 mi (2.4 km) NE Laura, outlet of drain, leg. LH, 4 May 1941, 120 (USNM 108858). 3.1 mi (5.0 km) W Princeville, leg. LH, 4 May 1941, 20 (USNM 108577). Piatt Co.: 1 mi (1.6 km) E White Heath, ditch by drain tile mouth, leg. W. V. Brigham, 5 May 1973, 1, 2 (INHS). Putnam Co.: 2 mi (3.2 km) N Putnam, Senachwine Creek, leg. JAB and LMP, 12 Jul 1974, 2, 1 (INHS). Saline Co.: N edge Harrisburg, roadside ditch, leg. LMP and E. L. List, 20 Jan 1974, 1 (INHS). Stark Co.: 3 mi (4.8 km) SE Wyoming, ditch, leg. LMP and JAB, 12 Jul 1974, 1 (INHS). Stephenson Co.: 3 mi (4.8 km) E Ridott, Pecatonica River, near spring, leg. LMP and LJS, 5 Sep 1974, 7, 9 (INHS). Tazewell Co.: 3 mi (4.8 km) S Hopedale, roadside ditch on Sugar Creek Drive, leg. LMP, 15 Sep 1977, 2 (INHS). Union Co.: 2.5 mi (4.0 km) NE Aldridge, seep near McCann School, leg. LH, 14 Apr 1940, 7 (USNM 108586). Vermillion Co.: 1.5 mi (2.4 km) N Fithian, tributary Stony Creek, tile outlet, leg. CWR and LMP, 9 Jun 1974, 1 (INHS). Oakville, tile outlet on W side of Oak St., leg. J. J. Lewis, 21 Jun 1978, 4, 3 (USNM). Warren Co.: 2.0 mi (3.2 km) SE Cameron, outlet of drain, leg. LH, 25 Apr 1942, 92 (USNM 108597). 5.2 mi (8.4 km) E Biggsville, outlet of drain, leg. LH, 25 Apr 1942, 68 (USNM 108594). Will Co.: Joliet, drilled well, leg. J. G. Brown, 9 Oct 1953, 1, 3 (INHS). Winnebago Co.: 3 mi (4.8 km) SE Seward, Mill Creek, leg. LMP and LJS, 5 Sep 1974, 1 (INHS). 2.5 mi (4.0 km) SSE Wempletown, tile outlet, leg. LMP and LJS, 4 Sep 1974, 2 (INHS). INDIANA. Henry Co.: 3.8 mi (6.1 km) N Knightstown, outlet of drain, leg. LH, 17 Apr 1942, 5 (USNM 108610) and 92 (USNM 108611). Lake Co.: 3.8 mi (6.1 km) SE Merrellville, outlet of drain, leg. LH, 20 Apr 1942, 64 (USNM 108607). Porter Co.: 0.5 mi (0.8 km) E Deep River, outlet of drain, leg. LH, 20 Apr 1942, 70 (USNM 108608). IOWA. Des Moines Co.: 3.6 mi (5.8 km) E Middletown, outlet of drain, leg. LH, 25 Apr 1942, 1 (USNM 108593). 0.2 mi (0.3 km) NW Danville, outlet of drain, leg. LH, 24 Apr 1942, 42 (USNM 108601). Henry Co.: 1.4 mi (2.3 km) SE New London, outlet of drain, leg. LH, 24 Apr 1942, 54 (USNM 108602). 1.7 mi (2.7 km) S Swedesburg, outlet of drain, leg. LH, 24 Apr 1942, 8 (USNM 108603). Washington Co.: 1.0 mi (1.6 km) S Haskins, outlet of drain, leg. LH, 24 Apr 1942, 18 (USNM 108599). 0.5 mi (0.8 km) S Haskins, outlet of drain, leg. LH, 24 Apr 1942, 28 (USNM 108600). MISSOURI. St. Louis Co.: Kirkwood, Osage Hills Golf Course, outlet of drain near hole 17, leg. LH, 13 Jun 1937, 31 (USNM 108588).

The following description supplements the brief original description of Steeves and Seidenberg (1971), the illustrations of which do not show some of the setae that are present on the gnathopod, pleopods 1 and 2, and the uropod. The setae on the distal exopod segment of the pleopod 2 are much longer than in their figure 3 and are plumose. Furthermore, A. kendeighi is not albinistic and blind as stated in the original description.

DESCRIPTION.—A large species with small eyes and light reddish-brown dorsal pigmentation. Length commonly 7–10 mm, largest individual examined 12.2 mm; reported up to 14.9 mm by Steeves and Seidenberg (1971). Body slender, linear, about 6.9× longer than wide; coxae visible in dorsal view. Margins of head, pereonites, and telson moderately setose. Head about 1.7× as wide as long; anterior margin concave; postmandibular lobes somewhat produced, broadly rounded; posterior margin of head slightly concave. Telson about 1.7× as long as wide, sides parallel, caudomedial lobe not pronounced.

Antenna 1 reaching to beginning of distal segment of antenna 2 peduncle; flagellum of about 10–12 segments; esthete formula 4-0-1. Antenna 2 reaching pereonite 7, last segment of peduncle about 1.3× length of preceding segment; flagellum of about 65–70 segments.

Mandibles with 4-cuspate incisors and lacinia mobilis; left mandible spine row with 12, right with 13 spines; palp with 2 apical spines. Maxilla 1, outer lobe with 13 spines, 1 subterminal seta and one medial lower seta; inner lobe with 5 apical setae, varying in plumosity, and 6 very slender subterminal setae. Maxilliped with 5–6 retinacula on right, 6–7 on left.

Male pereopod 1 propus about 1.6× as long as wide. Palm slightly concave with large proximal process, slightly bicuspate under high magnification; mesial short, broad, bicuspate process crowding distal lower, broad, slightly bicuspate process. Dactyl flexor margin with rounded boss; dactyl with 8 weak distal medial spines. Female pereopod 1 propus more slender than , about 1.9× as long as wide; palm slightly concave with large proximal spine and small distal triangular process. Dactyl flexor margin with small rounded boss, dactyl with 5–6 distal spines. Pereopod 4 similar in both sexes, moderately setose; dactyl of and with 2 medial spines.

Male pleopod 1, protopod about 0.6× length of exopod, with 5–6 retinacula. Exopod about 1.9× length of protopod, lateral margin concave, distally with 6 long setae interspersed with about 13 smaller setae, and distolateral row of minute setae. Male pleopod 2, exopod proximal segment with 3 short plumose setae and 2 minute setae, distal segment oval with about 19 long plumose setae, distal setae generally more elongate than proximal setae; endopod with rather elongate basal apophysis, inner margin of endopod rather straight, tip ending in 4 processes, cannula extending distally, not reaching beyond caudal process, apically blunt; caudal process low, broadly rounded, truncate distally; lateral process finger-like, extending slightly beyond caudal process; mesial process not extending to apex of cannula, broad, sides parallel, apically slightly concave. Female pleopod 2 with 19 plumose setae laterally. Pleopod 3, protopod about 0.6× length of exopod; exopod with 10 setae distally. Pleopod 4 with pattern A; proximal spines present.

Uropod about 1.6× length of telson; protopod about 1.2× length of endopod, 4.2× length of exopod.

ETYMOLOGY.—Named in honor of Dr. S. Charles Kendeigh.

RELATIONSHIPS.—Steeves and Seidenberg (1971) regarded Caecidotea kendeighi as a species unrelated to other asellids; however, this species seems to clearly fit the diagnosis of the hobbsi group as defined by Steeves (1966). The addition of C. kendeighi to the hobbsi group would greatly extend the known range of this group, now limited to Florida, Georgia, and southeastern Tennessee. The presence of eyes, the long proximal process on the gnathopod palm, and the morphology of the pleopods 1 and 2 distinguish C. kendeighi from other species of the hobbsi group.

HABITAT.—The majority of the records of C. kendeighi are from the outlets of drain tiles, leading into drainage ditches, used to drain wet fields for agricultural use (Figure 11b). Drain tiles provide ideal conditions for the collection of phreatobites.

C. kendeighi has also been taken from a single cave locality, Wildcat Cave in Hancock County, in 1942 and 1975. Its occurrence there on 2 widely separated occasions suggests that this is a permanent population. Specimens from Wildcat Cave do not differ morphologically from those taken from soil habitats.

RANGE.—Caecidotea kendeighi is found throughout the Illinois Basin, but exhibits no marked correlation with any stratigraphic unit (Figure 1). This species is associated with numerous tributaries of the Ohio and Mississippi rivers, most notably the Illinois River basin, and it has been suggested previously by Peck and Lewis (1978) that coarse stream sediments may have provided a means of dispersal into the glaciated lowlands the species inhabits. Peck and Lewis noted that C. kendeighi is only rarely taken in the coal field region of east-south central Illinois, a generalization which still seems to be true with a few exceptions. This may be a product of a lack of collecting. Competition with C. beattyi is also a possible explanation for its rarity there.

The soil habitats from which C. kendeighi is normally collected occur in areas of loess with depths from 0 to 300 inches, along with the Pleistocene sediments of the Wedron and Glasford Formations. The Union Co. locality occurs in an area where alluvium is present (Willman and Frye, 1970).

The vast majority of available collections of C. kendeighi were taken from the Central Lowlands Province, where the species occurs as far as 320 km (200 mi) northwards from the Illinoian glacial boundary and 240 km (150 mi) from the Wisconsinan boundary. The species seems to be widespread in the area covered by the Wisconsin glacier, despite the limited time available for dispersal into the area. Its presence in Union and Saline counties, south of the Illinoian glacial boundary, suggests the possibility that glacial refugia for the species occurred there, from which northward dispersal occurred after the ice had retreated. Such dispersal from a refugium has been suggested for the amphipod Bactrurus mucronatus (Forbes, 1876), which often occurs with C. kendeighi, by Peck and Lewis (1978).

Holsinger (1978, 1980) argues that some small species of subterranean crustaceans might have survived in groundwater refugia during glacial conditions. His theory offers an explanation alternative to postglacial migration for the occurrence of C. kendeighi in glaciated areas.