Typhloelmis Barr, 2015

Barr, Cheryl B., Gibson, J. Randy & Diaz, Peter H., 2015, TyphloelmisBarr (Coleoptera: Elmidae: Elminae), a New Stygobiontic Riffle Beetle Genus with Three New Species from Texas, USA, The Coleopterists Bulletin 69 (4), pp. 531-558 : 531-558

Typhloelmis Barr , new genus

( Figs. 5–22 , 29–36 )

Type Species. Typhloelmis sanfelipe Barr , new species, here designated.

Adult Description. Body form oblong, slender; depressed dorsally, convex ventrally. Cuticle moderately sclerotized, covered with whitish powderlike plastron on most surfaces except for antennae, mouthparts, scutellum, elytral suture and basal margin, and tarsi; plastron often absent or abraded at frons, pronotal apex and base, prosternum, legs, and near sutures and appendages; cuticle shiny and translucent where bare ( Figs. 6–8 ). Dorsum with prominent, flat, widely spaced granules bearing short, pale setae; carinae, striae, and punctures absent ( Figs. 5–12 ). Head: Retractile; generally spherical but with depressed frons, convex vertex and occiput; epicranial sutures obvious if head extended; plastron present except on mouthparts, but often mostly abraded. Eyes absent ( Figs. 9 , 11–13, 15 ). Antenna with 11 antennomeres; antennomeres 1–10 usually cone-shaped, sometimes nearly spherical; antennomeres 1 and 11 longest, subequal, each more than 2X longer than antennomeres 2–10; antennomere 2 variable; antennomeres 3 and 4 smallest; antennomeres 5–10 only slightly increasing in length distally, each bearing prominent, ventral, erect setae; antennomere 11 fusiform, bearing short, stout subapical setae ( Figs. 6–18 ). Clypeus convex, narrowly rectangular, about as wide as distance between antennal insertions; basal margin arcuate, distal margin truncate; surface granulate with sparse, pale, short setae. Mandible with 2 short teeth. Maxillary palpus with 4 palpomeres; apical palpomere subcylindrical, curved, nearly as long as combined length of basal 3 palpomeres, tip with oval sensory pit. Labrum convex, rectangular, shorter and narrower than clypeus; apicolateral angles broadly rounded, apical margin with fringe of pale setae; medial surface glabrous. Labial palpus with 3 palpomeres; apical palpomere subovoid, curved, slightly longer than combined lengths of basal 2 palpomeres and more than 2X as wide, tip with oval sensory pit. Pronotum: Rectangular, about 1/3 longer than wide, laterally marginate, without carinae, striae, or punctures ( Figs. 5–15 ). Disc convex at apex (pronotum and prothorax together forming a circle around head in frontal view), flattened medially; low protuberance with short, shallow, longitudinal sulcus present near basal midline; shallow, semicircular depression present on each side between basolateral angle and low protuberance. Anterior margin subtruncate; lateral margins slightly arcuate with row of granules or teeth; basal margin sinuate with acute basolateral angles. Disc with plastron except where abraded at anterior and basal margins; anterior and apicolateral margins with short, recurved, pale setae; scattered granules with similar, associated setae. Elytron: Narrowly elongate, over 4X as long as wide, together slightly wider than pronotum, widest about 1/4 distance from broadly rounded apex; dorsoventrally flattened except for convex apical 1/3. Laterally marginate with row of granules or teeth. Disc without carinae, costae, striae, or punctures; prominent, flat, widely spaced granules visible above plastron; scattered short, pale setae present ( Figs. 5–12 ). Elytral suture fused ( Fig. 19 ). Scutellum: Small, anterior margin broadly rounded; shiny, without plastron ( Figs. 6–8 , 29–30 ). Metathoracic wings: Absent. Legs: Long and slender; length of prothoracic leg similar to that of mesothoracic leg, metathoracic leg longest; prothoracic leg most stout, metathoracic leg thinnest ( Figs. 6–12 ). Procoxa large, spherical, closely spaced; mesocoxa spherical, slightly smaller than procoxa, more widely spaced; metacoxa transverse, space between metacoxae similar to that of mesocoxae, wider than that of procoxae. Femur plus trochanter slightly longer than tibia on pro- and metathoracic legs, subequal on mesothoracic leg; moderately granulate and setose, with or without plastron; profemur more stout than meso- and metafemora. Tibia about 2X as long as tarsus; granulate and spinose at distal 2/3, with or without plastron; protibia with fringe of long, pale setae (tomentum) on medial surface. Tarsus with plastron absent; tarsal formula 5-5-5; protarsus shortest, metatarsus longest; tarsomere 5 enlarged and about as long as previous 4 together; tarsomeres 1–4 with sparse ventral setae; claws simple, without teeth; metatarsal claws longest. Venter: Prosternum long anterior to procoxae; apical 1/4–1/3 lacking granules and plastron, shiny and bare except for sparse, pale setae, translucent at anterior margin; basal 2/3–3/4 with numerous, closely spaced granules and sparse, pale setae; plastron present but often abraded and may appear lacking. Prosternal process variable, elongate or triangular ( Figs. 16–18 ). Hypomeron covered with plastron. Suture between prosternum and hypomeron open at apical 1/4–1/5, forming a slight notch. Mesoventrite small, covered with plastron, granulate; deep fovea bounded by 2 carinae for insertion of prosternal process. Metaventrite nearly as long as prosternum; covered with plastron, sparse setae, and granules. Hypomeron with plastron and closely spaced granules; dense patch of tomentum in shallow depression adjacent to mesoventrite. Abdomen ( Figs. 9, 10 , 12 , 34 ) with 5 ventrites; ventrites 1–4 decreasing in length toward apex, apical ventrite 5 longest; sparse, scattered granules present near lateral margins; apical ventrite with fringe of setae at apex; plastron present. Epipleuron covered with plastron; granules scattered and few. Genitalia: Male ( Figs. 20, 21 ) and female genitalia typical of Elminae , with no features unique to the genus.

Adult Diagnosis. Typhloelmis does not resemble any known elmid genus. Besides stygobiontic modifications which include the lack of eyes ( Figs. 9 , 11–13, 15 ) and wings, it possesses an unusually extensive dorsal plastron ( Figs. 6–8 ) and a fused elytral suture ( Fig. 19 ), and lacks pronotal and elytral features such as punctures, striae, costae, and carinae ( Figs. 6–12 ). Couplets for insertion into existing North American generic keys ( Brown 1976; White and Roughley 2008) follow. Couplet 13 below is altered from White and Roughley (2008), but it is identical to couplet 49 of Brown.

13 (9′) Maxillary palpi 3-segmented; markings, if present, transverse ...... Narpus Maxillary palpi 4-segmented; markings, if present, longitudinal........13.5

13.5 (13) Eyes present; elytra with striae; pronotum and elytra without plastron .... ....................................... Dubiraphia Eyes absent; elytra without striae; pronotum and elytra with plastron........... ......................................... Typhloelmis

Etymology. A combination of typhlo from the Greek typhlos, meaning blind, plus elmis the nominate genus of the family Elmidae . Gender: feminine.

Larval Description. Terminal instar ( Fig. 22 ). Elateriform (cylindrical), lightly sclerotized, color pale yellow to yellow-brown; surface with sparse,

long, pale, erect setae; body length 3.5–5.9 mm (excluding head) and width 0.35–0.65 mm (n = 3). Head: Partially retracted into pronotum, oval in frontal view, frons dorsally depressed; few to numerous stout spines present at frontal margin, encircling antennal base, and posterior-laterad to antennal base. Antenna with 3 antennomeres, inserted laterad of mandible; antennomere 2 with long, pale, apical seta. Stemmata absent. Clypeus transverse; distal margin with posteriorly recurved, marginal brush of long, fine setae. Labrum transverse, lateral margins rounded. Mandible with 3 apical teeth of similar size. Maxillary palpus with 4 palpomeres. Labial palpus with 2 palpomeres. Thorax: Dorsal surfaces covered with evenly spaced, setiferous granules separated by about 1–2X their diameters; lateral and dorsal surfaces with sparse, short to long, erect, pale setae; posterior margins with fringe of evenly spaced setae originating from row of granules. Prothorax about as long as combined lengths of meso- and metathoraces; shallow, transverse depression 1/3–1/2 distance from anterior margin. Prosternum lacking posterior sternum such that procoxal cavities are open posteriorly;

15) T. finegan .

postpleurites divided into 2 pairs of sclerites. Meso- and metathoraces of similar length; mesothorax with 2 dorsolateral spiracles at anterior 1/4. Meso- and metasterna each with antero-medial tumescence bearing several stout spines; pleurites divided into 2 pairs of sclerites. Legs: With patches of spines, most prominent on meso- and metathoracic legs with dense spines on anterior surfaces including coxal; prothoracic leg with sparse spines on posterior surfaces including coxal, occasional long setae present. Abdomen: Cylindrical in cross-section; surface covered dorsally and ventrally with widely spaced granules bearing short, recumbent setae. Segments 1–8 of similar size, each with pair of lat- eral spiracles at anterior 1/4; dorsal surface with sparse, scattered, long, erect setae; lateral margin with few, grouped, long, erect setae mostly at posterior 1/4; posterior margin of each with fringe of long, recumbent setae. Segment 1 with tergopleural and sternopleural sutures forming pleurites; pleural sutures and pleurites absent on segments 2–8. Segment 9 about 0.5X longer than preceding segments; tip emarginate and slightly crenulate with 2 lateral teeth in dorsal view, forming an approximate 45° angle profile in lateral view; ventral operculum occupying apical 1/3, fringed laterally and apically with pale setae. Gills and pair of hooks present beneath operculum.

Larval Diagnosis. The larva of Typhloelmis is unusual among the Elmidae in having abdominal pleurites present only on the first segment and lacking on the remaining segments. No other elmid larva in North America lacks tergopleural and ster- nopleural sutures on abdominal segments 2–8, nor do any others lack stemmata.

Remarks/Discussion. A total of nine intact larvae and one partial larva associated with adult specimens were collected as follows: Typhloelmis

adults: T. caroline is the smallest (3.50 mm long and 0.35 mm wide); T. sanfelipe is intermediate (4.70 mm long and 0.50 mm wide); and T. finegan is the largest (5.90 mm long and 0.65 mm wide). caroline new species, three + one partial larvae; T. sanfelipe , two larvae; Typhloelmis finegan new species, four larvae. Because the species are likely allopatric, the associated larvae are assumed to be the same species as the adults with which they were collected. Terminal larval instars of each species were used in formulating the composite generic description and species comparisons. A revision of existing taxonomic larval keys is not provided because the number of abdominal pleurites is an important generic character which is basal in such keys.

Larval Species Comparison. Although only a small number of late instars were available for comparison, some apparent morphological differences were noted among the larvae of the three species. The tarsungulus (pretarsus) of T. caroline is short and stout, less than 1/2 length of the previous segment, deflexed and not curved; the tarsunguli of T. finegan and T. sanfelipe are longer, about 2/3 length of the previous segment, curved and sharp-tipped. The apex of the terminal abdominal segment of T. finegan is the most deeply emarginate (semicircular), with acute, very sharp-tipped lateral teeth; that of T. sanfelipe is the most shallowly emarginate (less than semicircular) with obtuse, blunt-tipped lateral teeth; and that of T. caroline is intermediate, shallowly emarginate (nearly semicircular) with acute, moderately sharptipped lateral teeth. The species also differ in the number and prominence of stout spines near the antennae, with T. sanfelipe having the least well-developed. Typhloelmis caroline is most poorly sclerotized of the three species and is paler in color as a result. The sizes of the three terminal instars measured are in relation to that of the

Typhloelmis caroline Barr , new species ( Figs. 1 , 6 , 9 , 13 , 16 , 20 )

Material Examined. H O L O T Y P E ♂ i n EMEC, labeled “ USA: Texas: Terrell County / Independence Creek Preserve / ( TNC), Caroline Springs / 30.4690°,-101.8035°, elev. 616m / 1/ 3-VIII-2007, collr. J. R. Gibson” // [genitalia vial] // “ HOLOTYPE Typhloelmis caroline Barr ” [red label, handwritten]. Seventeen paratypes [yellow labels] were examined from the same locality with the following dates and collectors: 11-IV-2007, J. R. Gibson & P. H. Diaz (1 EMEC); 30-IV-2007, J. R. Gibson & E. Chappell (1 EMEC, 2 TAMU); 19-V-2007, J. R. Gibson & J. Denton (2 EMEC); 22-VI-2007, J. R. Gibson (5 EMEC, 1 USNM); 1/ 3-VIII-2007, J. R. Gibson (2 EMEC, 2 USNM); 22/ 25-X-2007, J. R. Gibson & C. B. Barr (1 EMEC). Two non-paratypes (specimens broken) with the following date and collector: 22-VI-2007, J. R. Gibson ( EMEC) (1 pinned, 1 in ethanol).

Description. Holotype male. Length 2.2 mm (elytra + pronotum), width 0.7 mm. Cuticle testaceous, translucent, with extensive whitish dorsal and ventral plastron; surface smooth, lacking dorsal carinae, striae, and punctures ( Figs. 6 , 9 ). Antenna: Color pale yellow; antennomeres 1–2 cone-shaped, wider distally than basally; antennomere 3 hemispherical, widest at base, closely appressed to antennomere 2; antennomere 4 spherical; antennomeres 5–10 nearly spherical, slightly wider distally than basally; antennomere 11 fusiform and acutely pointed ( Figs. 6 , 9 , 13 , 16 ). Head: Color testaceous, darker at clypeal margin; surface bearing evenly spaced, small granules and short setae. Eyes absent ( Figs. 9 , 13 , 16 ). Labrum darker at clypeal margin with long, pale setae on distal 1/2. Clypeus and palpi pale yellow. Mandible dark brown with 2 short, acute teeth of nearly similar size and shape. Pronotum: Color generally testaceous, darker at apical and basal margins, covered with whitish plastron ( Fig. 6 ). Longer than wide; length 0.8 mm, width 0.5 mm near midline; nearly parallel-sided, width at base and apex subequal, slightly narrower than at middle ( Figs. 6 , 9 , 13 ). Lateral margins uneven, crenulate with low, elongate granules; apicolateral area slightly flattened and constricted; basolateral angles acute. Disc with short, sparse setae and widely spaced, large, shiny, flat granules emergent from plastron. Elytron: Color testaceous, darker at basal margin and suture, covered with whitish plastron ( Fig. 6 ). Length 1.4 mm, width 0.3 mm at widest point near apical 1/3. Disc with short, sparse setae; widely spaced, large, shiny, flat granules emergent from plastron loosely arranged into 4 longitudinal rows, occasional granules between rows. Lateral margin uneven, crenulate with low, elongate granules ( Figs. 6 , 9 ). Leg: Color of coxa, trochanter, femur, and tibia mostly testaceous; tarsus pale yellow. Plastron remnant present on profemur only. Femur moderately granulate and setose, more so ventrally. Tibia with ventral row of stout spines at distal 2/3 and encircling apex; pro- and mesotibiae with numerous spines, metatibia with fewer spines ( Fig. 9 ). Protibia with fringe of long, pale setae (tomentum) on medial surface ( Figs. 6 , 9 , 13 , 16 ). Tarsomeres 1–4 with short, stout setae at ventral apex; tarsomere 5 with few, fine setae on ventral surface and at apex. Protarsomere 5 with distal 1/2 bulbous, especially in lateral view. Claws very slender and slightly curved. Venter: Color testaceous, covered with plastron except where abraded. Prosternum ( Fig. 16 ) covered with numerous, evenly spaced granules and sparse setae; anterior 1/3 bare of plastron; prosternal process elongate, very narrow between procoxae, slightly constricted at middle, widened toward rounded apex. Metaventrite ( Fig. 9b ) with widely spaced granules and setae; anterior margin truncate between mesocoxae; metakatepisternal suture slightly sinuate, each arm slightly curved anteriorly, discrimen not obvious. Abdominal ventrites ( Fig. 9b ) with widely spaced granules and setae; disc of apical ventrite with fewer scattered granules and setae, apex with fringe of stout setae; intercoxal process of ventrite 1 broadly rounded. Male genitalia: Paramere color testaceous, penis and phallobase paler. In dorsal view ( Fig. 20 ), parameres with outer margins generally straight and parallel to each other except near tips, inner margins curved; tips rounded, apical 1/8 unpigmented, transparent. Penis barely longer than parameres, narrowly tapered toward unpigmented, rounded apex; base width about 1/2 as wide as phallobase, tip slightly narrower than paramere tips; longitudinal, testaceous spicule present on ventral surface.

Variation. Females averaged slightly larger than males, otherwise the sexes are externally similar. The smallest individual, a male, measured 2.1 mm long and 0.6 mm wide; the largest, a female, measured 2.5 mm long and 0.7 mm wide. The most notable difference between individuals is the degree of plastron abrasion present. Slight morphological differences include antennal and tarsal color (testaceous or pale yellow), shape of antennomeres 5–10 (nearly spherical or broadly cone-shaped), presence or absence of spinose granules on anterolateral pronotal surfaces, elytra with disc granules loosely arranged into four longitudinal rows or not, and degree of constriction of the prosternal process between the procoxae.

Diagnosis. Typhloelmis caroline ( Fig. 6 ) most closely resembles T. sanfelipe ( Fig. 7 ) but is smaller on average, 2.1–2.5 mm in length compared to 2.3–2.9 mm for the latter species. Morphological differences for T. caroline ( Figs. 6 , 9 , 13 , 16 ) are: (1) pronotum and elytra margined with low, elongate, irregularly spaced granules; (2) pronotum with few or no spinose granules on anterolateral surfaces; (3) prosternal process very narrow with a distinct constriction between the procoxae; (4) antennomere 3 hemispherical, widest at base, and closely appressed to antennomere 2. Conversely, for T. sanfelipe ( Figs. 7 , 10 , 14 , 17 ) they are: (1) pronotum mar- gined with irregularly shaped and angled, peg-like teeth; elytral margin finely serrate; (2) pronotum with numerous spinose granules on anterolateral surfaces; (3) prosternal process narrow with a slight or no medial constriction; (4) antennomere 3 not hemispherical and not closely appressed to antennomere 2. The male genitalia of these two species are quite similar, but in T. caroline ( Fig. 20 ) the penis is slightly narrower than in T. sanfelipe ( Fig. 21 ). Typhloelmis finegan ( Figs. 8 , 12 , 15 , 18 ) is unlikely to be confused with T. caroline because it is much larger (> 4 mm vs. <2.5 mm long); the prosternal process is broad and triangular rather than narrow and elongate; the pronotum is margined with rounded, evenly spaced teeth instead of low, elongate granules; antennomeres 1–10 are similarly cone-shaped; and a fringe of tomentum is present on all tibiae (protibiae only in T. caroline ).

Etymology. Caroline, a noun in apposition, from the type locality, Caroline Springs.

Habitat. Formerly owned by the Oasis Ranch and known as T5 Springs, Caroline Springs ( Figs. 1 , 3, 4 , 23, 24 ) are a small group of perennial springs located at The Nature Conservancy’ s (TNC) Independence Creek Preserve in Terrell County, Texas, about 26 km southeast of Sheffield. The area is contained within the Chihuahuan Desert Ecoregion ( Bureau of Economic Geology 2010) and the Stockton Plateau. The springs issue from early Cretaceous Edwards Limestone ( Bureau of Economic Geology 1992) ( Fig. 3 ) and appear to be fed by deep groundwater upwelling through vertical fractures connected to an aquifer channel in the Paleozoic basement rock which is associated with Independence Creek ( Brown 2003). Brune (1981) reported spring discharges of 60–370 L/s from five measurements taken during the years from 1917 to 1976; TNC cites a discharge of 3,000 –5,000 gal/min (227–379 L/s) on their Independence Creek Preserve website.

Associated Fauna. Caroline Springs is the only known locality for the stygobiontic dytiscid beetle E. naturaconservatus ( Miller et al. 2009) . Other subterranean aquatic fauna present in the outflow of the springs includes the isopods (Crustacea) Cirolanides texensis Benedict and unidentified Lirceolus Bowman and Longley and the amphipods (Crustacea) Artesia subterranea Holsinger , Parabogidiella americana Holsinger , Seborgia hershleri Holsinger , and unidentified Stygobromus Cope. Epigean (surface-dwelling) riffle beetles present in the springs include Heterelmis glabra (Horn) , unidentified species of Macrelmis Motschulsky , Microcylloepus Hinton (Elmidae) and Psephenus texanus Brown and Arrington (Psephenidae) ; the population of H. glabra at the springs was included in a population genetics study of Heterelmis Sharp by Gonzales (2008). An unidentified species of marsh beetle in the genus Scirtes Illiger (Scirtidae)

24) Spring head with drift net.

has also been collected from the springs. The springassociated Manantial roundnose minnow, Dionda argentosa Girard , occurs in the headwaters of Independence Creek fed by Caroline Springs ( Carson et al. 2010).

Typhloelmis sanfelipe Barr , new species ( Figs. 1 , 5 , 7 , 10 , 11 , 14 , 17, 19 , 21 , 29–36 )

Material Examined. HOLOTYPE ♂ in EMEC, labeled “ USA: Texas: Val Verde Co. / Del Rio, San Felipe Springs / 29.3724°, − 100.8860° / elev. 292m / XI-2007, D. Foley ” // [genitalia vial] // “ HOLO- TYPE Typhloelmis sanfelipe Barr ” [red label, handwritten]. Sixteen paratypes [yellow labels] were examined from the same locality with the following dates and collectors: 16-VIII-2007, D. Foley & J. R. Gibson (3 EMEC, 1 USNM); VIII/ IX-2007, D. Foley (1 EMEC, 1 TAMU); 26-X-2007, J. R. Gibson & C. B. Barr (1 EMEC); XI-2007, D. Foley (5 + fragments EMEC, 1 TAMU, 2 USNM); 31-VIII-2008, J. R. Gibson (1 EMEC).

Description. Holotype male. Length 2.6 mm (elytra + pronotum), width 0.8 mm. Cuticle testaceous, translucent, with extensive whitish dorsal and ventral plastron; surface smooth, lacking dorsal carinae, striae, and punctures ( Figs. 5 , 7 , 10 , 11 , 19 , 29 ). Antenna: Color pale yellow; antennomeres 1–10 cone-shaped, antennomere 1 largest, antennomere 2 next largest; antennomeres 3–10 smaller, stoutly cone-shaped, progressively longer distally; antennomere 11 narrowly fusiform and acutely pointed ( Figs. 7 , 10 , 14 , 17 ). Head: Color testaceous, darker at clypeal margin; surface bearing evenly spaced, small granules and short setae. Eyes absent ( Figs. 11 , 17 ). Labrum, clypeus, and palpi pale yellow; labrum with long, pale setae on distal 1/2. Mandible dark brown with 2 short, acute teeth; lower tooth slightly longer and more slender than the upper. Pronotum: Color testaceous, darker at base, covered with whitish plastron ( Fig. 7 ) except where abraded anteriorly. Longer than wide; length 0.9 mm, width 0.7 mm; narrowest at apical 1/3, nearly parallel-sided medially, narrower at base ( Figs. 5 , 7 , 10 , 14 ). Lateral margins crenulate with small, irregular, peg-like teeth, many angled anteriorly; basolateral angles acute. Disc medially with widely spaced, small, round granules emergent from plastron; spinose granules numerous anterolaterally; setae sparse, short, recurved, most numerous on apical margin. Elytron: Color testaceous, darker at basal margin and suture, covered with whitish plastron except for small abraded spots ( Figs. 7 , 29 ). Length 1.7 mm, width 0.4 mm at widest point. Disc with short, sparse setae; widely spaced, small, round granules emergent from plastron, becoming protuberant near lateral margins. Very shallow lateral depression just before elytral apex. Lateral margin finely serrate in dorsal view with evenly spaced, posteriorly angled teeth ( Figs. 5 , 7 , 10 ). Leg: Color of coxa, trochanter, femur, and tibia red-brown; tarsus red-brown at basal 1/2, testaceous at apical 1/2. All legs with plastron remnants present on trochanter and ventral surface of femur. Femur with numerous large granules and fine setae. Tibia with ventral row of stout spines at distal 2/3 and encircling apex; pro- and mesotibiae with numerous spines, metatibia with fewer spines ( Figs. 10 , 11 ). Protibia with fringe of long, pale setae (tomentum) on medial surface ( Figs. 5 , 10 , 14 , 17 ). Tarsomeres 1–4 with short, stout setae at ventral apex; tarsomere 5 with few setae along length of ventral surface. Protarsomere 5 with distal 1/2 bulbous, especially in lateral view. Claws slender and moderately curved. Venter: Color testaceous, covered with plastron except where abraded. Prosternum ( Fig. 17 ) covered with numerous, evenly spaced granules and short, sparse setae; anterior 1/3 bare of plastron; prosternal process elongate, narrow, width nearly uniform between coxae, apex broadly rounded. Metaventrite ( Fig. 10b ) with widely spaced granules and setae; anterior margin truncate between mesocoxae; metakatepisternal suture slightly sinuate, each arm slightly curved anteriorly, discrimen shallow. Abdominal ventrites ( Fig. 10b ) with widely spaced granules and short, sparse setae; disc of apical ventrite with fewer scattered granules and setae, apex with fringe of stout setae; intercoxal process of ventrite 1 broadly rounded. Male genitalia: Parameres testaceous, penis and phallobase paler. In dorsal view ( Fig. 21 ), parameres with outer margins generally straight and parallel to each other except near tips, inner margins curved; tips rounded, apical 1/8 unpigmented, transparent. Penis slightly longer than parameres, broadly tapered toward unpigmented, narrowly rounded apex; basal width at least 2/3 as wide as phallobase, tip narrower than paramere tips; longitudinal, testaceous spicule present on ventral surface.

Variation. Individuals ranged in size from 2.3 mm long and 0.7 mm wide (female) to 2.9 mm long and 0.9 mm wide (male). The sexes are externally similar in appearance and in size. The most notable difference between individuals is the degree of plastron abrasion. Slight differences include color of the coxae, femora, and tibiae (testaceous or redbrown) and tarsi (testaceous or pale yellow), shape of antennomeres 3–5 (stoutly cone-shaped or nearly spherical), and prosternal process width (nearly uniform between procoxae as in holotype or slightly constricted at middle).

Diagnosis. Typhloelmis sanfelipe ( Fig. 7 ) most closely resembles T. caroline ( Fig. 6 ) but is slightly larger on average, 2.3–2.9 mm in length compared to 2.1–2.5 mm for the latter species. Morphological differences for T. sanfelipe ( Figs. 7 , 10 , 14 , 17 ) are: (1) pronotum margined with irregularly shaped and angled, peg-like teeth; elytral margin finely serrate; (2) pronotum with numerous spinose granules on anterolateral surfaces; (3) prosternal process narrow with a slight or no medial constriction; (4) antennomere 3 not hemispherical and not closely appressed to antennomere 2. Conversely, for T. caroline ( Figs. 6 , 9 , 13 , 16 ) they are: (1) pronotum and elytra margined with low, elongate, irregularly spaced, granules; (2) pronotum with few or no spinose granules on anterolateral surfaces; (3) prosternal process very narrow with a distinct constriction between the procoxae; (4) antennomere 3 hemispherical, widest at base, and closely appressed to antennomere 2. The male genitalia of these species are quite similar, but in T. sanfelipe ( Fig. 21 ) the penis is slightly broader than in T. caroline ( Fig. 20 ). Typhloelmis finegan ( Figs. 8 , 12 , 15 , 18 ) is unlikely to be confused with T. sanfelipe because it is much larger (> 4 mm vs. <3 mm long); the prosternal process is broad and triangular rather than narrow and elongate; the pronotum is margined with rounded, evenly spaced teeth instead of irregularly shaped and angled, peg-like teeth; antennomeres 1–10 are similarly cone-shaped; and a fringe of tomentum is present on all tibiae (protibiae only in T. sanfelipe ). In addition, T. sanfelipe has femora with prominent large granules unlike the femora of the other species.

Etymology. Sanfelipe, a noun in apposition, from the type locality, San Felipe Springs.

Habitat. San Felipe Springs, located at the junction of the Chihuahuan Desert and Southern Texas Plains ecoregions ( Bureau of Economic Geology 2010), is the third-largest group of exposed (surface) springs in Texas and the largest of the Edwards-Trinity Aquifer with an average discharge of 79.27 mgd (3473 L/s) (Eco-Kai Environmental, Inc., and Hutchison 2014). The spring group is comprised of about 10 individual springs discharging from early Cretaceous Salmon Peak Limestone ( Bureau of Economic Geology 1992), with the three major springs located on the San Felipe Country Club golf course in the city of Del Rio, Texas ( Fig. 1 ). Of these, the two largest are utilized as water supply by Del Rio. The smaller group (referred to as “Spring No. 1” in Brune 1981) is essentially unmodified despite concrete steps at the head of the spring run ( Figs. 25, 26 ). This group, the collection site for T. sanfelipe , consists of two springs that head a short (13 m long) spring run ( Figs. 25, 26 ) that flows into San Felipe Creek, emptying into the Rio Grande River about 10 km downstream.

Associated Fauna. San Felipe Springs is the type locality for the single-site endemic stygobiontic dytiscid beetle P. felipi and the epigean riffle beetle Macrelmis shoemakei Brown (1971) (Elmidae) , which also occurs at one locality in the adjacent state of Coahuila, Mexico. Other subterranean aquatic fauna present in the outflow of the springs includes the isopods C. texensis , Lirceolus sp. , Mexistenasellus coahuila Cole and Minckley , and Speocirolana hardeni Bowman and the amphipods A. subterranea , P. americana, Paramexiweckelia ruffoi Holsinger , S. hershleri , and Stygobromus sp. In addition to M. shoemakei , epigean riffle beetles present in the spring runs include Hexacylloepus ferrugineus (Horn) , Macrelmis texana (Schaeffer) , Microcylloepus similis (Horn) , Phanocerus clavicornis Sharp , Stenelmis occidentalis Schmude and Brown (Elmidae) , Lutrochus luteus LeConte (Lutrochidae) , and P. texanus (Psephenidae) . The springs are designated critical habitat for the federally threatened Devils River minnow, Dionda diaboli Hubbs and Brown (USFWS 2007) , which occurs there sympatrically with D. argentosa .

Figures

Fig. 5. Typhloelmis sanfelipe, genotype, adult habitus, dorsal view.

Figs. 6–8. Typhloelmis species, adult dry specimens, dorsal view (length = pronotum + elytra). 6) T. caroline, ♂, length 2.2 mm; 7) T. sanfelipe, ♀, length 2.5 mm; 8) T. finegan, ♀, length 4.1 mm.

Figs. 9–10. Typhloelmis species, adult wet specimens. 9) T. caroline, a) Dorsal view, b) Ventral view; 10) T. sanfelipe, a) Dorsal view, b) Ventral view.

Figs. 11–12. Typhloelmis species, adult wet specimens. 11) T. sanfelipe, lateral view; 12) T. finegan, a) Dorsal view, b) Ventral view.

Figs. 13–15. Typhloelmis species, adult wet specimens, anterior dorsal view. 13) T. caroline; 14) T. sanfelipe;

Figs. 16–19. Typhloelmis species, adult wet specimens, ventral view. 16) T. caroline, anterior; 17) T. sanfelipe, anterior; 18) T. finegan, anterior; 19) T. sanfelipe, fused elytra.

Figs. 20–21. Typhloelmis species, male genitalia, dorsal view. 20) T. caroline; 21) T. sanfelipe.

Fig. 22. Larva of Typhloelmis finegan, a) Dorsal view, b) Lateral view, c) Ventral view.

Figs. 29–34. Typhloelmis sanfelipe, plastron. 29) Elytra, 164X; 30) Scutellum, 1,700X; 31) Elytral suture, 2,420X;

Figs. 35–36. Typhloelmis sanfelipe, plastron. 35) Elytron, abraded area, 4,380X; 36) Elytron, abraded area and plastron structure, 10,000X.

Figs. 1–2. 1) Map of Terrell and Val Verde counties, Texas, showing the type localities of Typhoelmis caroline at Caroline Springs, Typhoelmis sanfelipe at San Felipe Springs, and Typhoelmis finegan at Finegan Springs; 2) Map of the Edwards and Trinity Aquifer regions of Texas. GWD = groundwater divide; black dots = type locality springs.

Figs. 3–4. Caroline Springs. 3) Submerged spring orifice with partially dissolved limestone substrate; 4) Drift nets in place over spring orifice.

Figs. 23–24. Caroline Springs, type locality of Typhloelmis caroline. 23) Spring run looking toward source;

Figs. 25–26. San Felipe Springs, type locality of Typhloelmis sanfelipe. 25) Spring run looking toward source beneath concrete steps; 26) Spring head with two drift nets.