58 U.S. NATIONAL MUSEUM BULLETIN 25 9 



Peduncular segment 4 of 2nd antenna without slender spines on ventral 

 margin; ])ropod palmar margin of gnathopod 1 slightly concave; telson 

 of female with up to 12 apical spines; springs on Rich Mt., Polk Co., Ark. 



S. montanus, new species 



Stygonectes tenuis tenuis (Smith), new status 



Figure 12 



Crangonyx tenuis Smith, 1874, pp. 656-657 [Type locahty: Wells at Middletown, 

 Conn.].— O. P. Hay, 1882, p. 145.— Underwood, 1886, p. 358.— Packard, 

 1888, p. 35.— Delia Valle, 1893, p. 682.— Stebbing, 1906, pp. 372-373.— 

 Banta, 1907, p. 80.— Weckel, 1907, pp. 50-51.— Holmes, 1909, p. 78.— 

 Stout, 1911, p. 570.— Kunkel, 1918, pp. 95-98, fig. 21. 



Eucrangonyx tenuis (Smith). — Spandl, 1926, p. 76. — Chappuis, 1927, p. 76. 



Stygonectes tenuis (Smith). — Schellenberg, 1936, p. 38. — Barnard, 1958, p. 74. — 

 Holsinger, 1966, p. 101. 



Synpleonia tenuis (Smith). — Shoemaker, 1938, p. 140. — Hubricht, 1959, p. 878 

 (in part). — Nicholas, 1960, p. 130 (in part). 



Material examined 



CONNECTICUT. — Middlesex Co. : wells at Middletown, male lectotype (YPM 4538) 

 and male syntype (YPM 4537); New Haven Co.; well at Westville, small male 

 and 2 small females (YPM 4536). new york. — New York Co.: spring in New 

 York Botanical Gardens, L. Hubricht, July 3, 1943 (LH). Maryland. — Talbot 

 Co.: well near Trappe, C. Willis, Jr., Aug. 4 and Oct. 10, 1923, November 1927 

 (USNM); Dorchester Co.: ditch, 3 miles W of Cambridge, R. W. Jackson, 

 Mar. 21, 1943 (LH). 



Diagnosis. — Medium-sized subterranean species readily distin- 

 guished from other species of Stygonectes by the large, elongate 2nd 

 antenna which is longer than the 1st antenna in larger males. Further 

 distinguished from S. allegheniensis, to which it is closely alUed, by the 

 deeply concave margins of the 1st gnathopods. S. t. tenuis sensu 

 strictu may be distinguished from S. t. jJotomacus by the diagnosis 

 given for the latter. Largest males, 12.00 mm; largest females, 9.75 mm. 



Generally corresponding to the redescription and figure by Kunkel 

 (1918) with the following additions and modifications: 



Male. — ^Antenna 1 up to 50 percent as long as body, with about 22 

 primary flagellar segments. Antenna 2 large, longer than antenna 1 

 in larger males; flagellum with 12 to 14 segments, penultimate segment 

 large, arcuate, much longer than terminal segment. Mouth parts 

 corresponding to those figured for S. t. j^otomacus (fig. 13) and as 

 follows: Mandibular palpal segment 3 with 6 or 7 long setae, segment 

 2 with 6 to 8 setae. Maxilla 1, inner plate with about 4 apical, plumose 

 setae. Maxilla 2, inner plate with 2 to 4 long, obliquely placed, 

 plumose setae. Maxilliped, inner plate with 3 or 4 (usually 3) thick, 

 apical spines. Inner lobes of lower lip rather broad. 



Gnathopod 1 : propod palmar margin rather deeply concave, armed 

 with a double row of 8 or 9 spine teeth; posterior angle with 1 large 



