Tytthus alboornatus (Knight)

Henry, Thomas J., 2012, Revision of the Plant Bug Genus Tytthus (Hemiptera, Heteroptera, Miridae, Phylinae), ZooKeys 220, pp. 1-114 : 10-13

Tytthus alboornatus (Knight) Figs 2 –4109– 112

Cyrtorhinus alboornatus Knight 1931: 172 (orig. descrip.).

Tytthus alboornatus : Carvalho and Southwood 1955: 27 (descrip., n. comb.); Carvalho 1958: 156 (cat.); Henry and Wheeler 1988: 457 (cat.); Schuh 1995 (cat.); Denno 1983: 702 (note); Hoffman 2000: 24 (note, distr.); Hines et al. 2005: 264 (note).

Diagnosis.

This species is distinguished by the small size, usually brachypterous hemelytra, overall dark brown coloration, with the basal third to half of the corium and clavus, and cuneus (or in brachypters the posterior margin of the corium) pale or white, the pale yellowish brown antennal segment I, the mostly dark brown femora and pale yellowish-brown tibiae and tarsi. Macropterous and brachypterous forms are known for both sexes.

This species is most similar in size and coloration to Tytthus wheeleri , sp. n. In Tytthus alboornatus , antennal segment I is pale yellowish brown and the posterior margin of each hemelytron in brachypters or the cuneus in macropters is pale or white, whereas in Tytthus wheeleri , antennal segment I is dark brown and the posterior margin of each hemelytron in brachypters and or cuneus in macropters is uniformly dark brown.

Description.

Macropterous male (n = 1, plus holotype in parentheses) (Fig. 2): Length to apex of hemelytron 2.21 mm (2.24 mm), length to base of cuneus 1.57 mm (1.66 mm), width across hemelytra 0.72 mm (0.77 mm). Head: Length 0.72 mm (0.26 mm), width across eyes 0.51 mm (0.54 mm), interocular width 0.30 mm (0.30 mm). Labium: Length [embedded in glue] (0.94 mm). Antenna: Segment I length 0.29 mm (0.37 mm), II 0.88 mm (1.06 mm), III 0.59 mm (0.72 mm), IV 0.48 mm (missing). Pronotum: Length 0.32 mm (0.35 mm), basal width 0.45 (0.72 mm).

Brachypterous male (n = 5): Length to apex of abdomen 1.34-1.57 mm, length to base of hemelytron (cuneus and membrane absent) 1.15-1.41 mm, width across hemelytra 0.58-0.62 mm. Head: Length 0.22-0.26 mm, width across eyes 0.50-0.59 mm, interocular width 0.29-0.30 mm. Labium: Length 0.83-0.86 mm. Antenna: Segment I length 0.29-0.30 mm, II 0.80-0.86 mm, III 0.53-0.64 mm, IV 0.45-0.61 mm. Pronotum: Length 0.24-0.29 mm, basal width 0.54-0.56 mm.

Coloration: Head: Brown to dark brown, with a small, vague, pale spot near inner margin of each eye; eyes dark brown to reddish brown. Labium: Yellowish brown, apex of segment IV darker brown. Antenna: Segment I pale yellowish brown; segments II–IV yellowish brown, sometimes becoming slightly darker brown. Pronotum: Uniformly shiny brown to very dark brown or fuscous. Mesoscutum: Hidden under base of pronotum in brachypters, narrowly exposed in macropters. Scutellum: Brown to dark brown, with apex pale. Hemelytron: Broadly dark brown, with basal one fourth and narrow apex or cuneus (in macropter) pale or white; membrane on only macropter fully developed, smokey brown. Ventral surface: Thoracic pleural areas brown to dark brown, ventral surface sometime paler yellowish brown; abdomen dark brown to fuscous, especially laterally, ventral area sometimes paler yellowish brown. Ostiolar evaporative area: Dark brown. Legs: Coxae pale yellowish brown to whitish, with bases dark brown; femora dark brown, pale yellowish brown at bases and apices; tibiae, tarsi, and claws pale yellowish brown.

Structure, texture, and vestiture: Head: Shiny, impunctate; broader than long, rounded anteriorly, truncate basally; set with short, recumbent, nearly bristlelike setae on vertex and frons. Labium: Extending beyond metacoxae to second or third abdominal segment. Pronotum: Shiny, impunctate, nearly rectangular, wider than long, anterior angles rounded, base truncate, calli indistinct, not differentiated from discal surface, only slightly raised and rounded; set with scattered, recumbent, brown to nearly black setae. Scutellum: Equilateral, impunctate, with a few scattered, short, recumbent setae. Hemelytron: Macropter with fully developed cuneus and membrane, including two closed cells or areoles; all other specimens (except one macropter) brachypterous (staphylinoid), with clavus fused (and claval suture absent) with corium, cuneal fracture and cuneus absent, and membrane absent or rarely with only a remnant narrow strip along truncate posterior margin, extending from about abdominal tergite IV to nearly to apex of abdomen; set with evenly scattered, short, recumbent brown setae.

Male genitalia: Left paramere (Fig. 109): Mitt-shaped; right arm long, stout; left arm short, apically acute. Right paramere (Fig. 110): Oval. Endosoma (Fig. 111): Slender, S-shaped, apex pointed. Phallotheca (Fig. 112): Relatively slender, apically acute.

Macropterous female (n = 1) (Fig. 3): Length to apex of hemelytron 2.45 mm, length to base of cuneus 1.85 mm, width across hemelytra 0.93 mm. Head: Length 0.32 mm, width across eyes 0.58 mm, interocular width 0.32 mm. Labium: Length 0.99 mm. Antenna: Segment I length 0.32 mm, II 0.91 mm, III 0.69 mm, IV 0.67 mm. Pronotum: Length 0.37 mm, basal width 0.86 mm.

Brachypterous “minor” female [see discussion below] (n = 10): Length to apex of abdomen 1.44-1.79 mm, length to apex of hemelytra 1.34-1.60 mm, width across hemelytra 0.58-0.80 mm. Head: Length 0.26 mm, width across eyes 0.43-0.53 mm, interocular width 0.29-0.30 mm. Labium: Length 0.80-0.91 mm. Antenna: Segment I length 0.26-0.27 mm, II 0.74-0.80 mm, III 0.53-0.59 mm, IV 0.48-0.61 mm. Pronotum: Length 0.27-0.29 mm, basal width 0.50-0.56 mm.

Brachypterous “major” female (n = 2) (Fig. 4): Length to apex of abdomen 2.02-2.30 mm, length to apex of hemelyra 1.60-1.86 mm, width across hemelytra 0.93-0.99 mm. Head: Length 0.27-0.30 mm, width across eyes 0.56-0.61 mm, interocular width 0.34-0.35 mm. Labium: Length 0.91-0.96 mm. Antenna: Segment I 0.30-0.32 length mm, II 0.90-0.96 mm, III 0.64 mm, IV 0.50 mm. Pronotum: Length 0.29-0.34 mm, basal width 0.59-0.64 mm.

Hosts.

Taken by A. G. Wheeler on inland saltgrass, Distichlis spicata (L.) Green [ Poeaceae ]; saltmeadow cordgrass, Spartina patens (Ait.) Muhl.; and sand cordgrass, Spartina bakeri Merr. [ Poeaceae ]. Denno (in litt, 2005) informed me that Tytthus alboornatus was extremely abundant only in Spartina patens in Tuckerton, New Jersey, but not in Spartina alterniflora where Tytthus vagus was restricted. Denno (1983) and Hines et al. (2005) reported that Tytthus alboornatus preys on eggs of the delphacids Tumidagena minuta McDermott and possibly Delphacodes detecta (Van Duzee) in Spartina patens .

Distribution.

Previously known only from Florida, New Jersey, New York, and Virginia ( Henry and Wheeler 1988, Hoffman 2000). New U. S. state records are Connecticut, Louisiana, South Carolina, and Texas. This distribution indicates that Tytthus alboornatus should occur in all coastal states from at least New England to Texas.

Discussion.

Tytthus alboornatus (Figs 2-4) is one of the smallest species in the genus, second in size only to the similar-appearing Tytthus wheeleri (Figs 50-52). Like Tytthus wheeleri , macropterous forms of this species are extremely uncommon or rare. Of the more than 50 specimens studied, I have found only two macropterous males, including the holotype (from Florida) and three macropterous females (from Connecticut and South Carolina).

In addition, populations include what I call “minor” and “major” females. Along the Connecticut and New Jersey coasts, specimens are much smaller (shorter and more slender), whereas farther south in South Carolina and Florida several specimens are considerably larger, with more well-developed pronota and hemelytra. Two macropterous females from Connecticut also were smaller than the macropter from South Carolina. This size difference may simply be due to more harsh or crowded conditions, with a more limited food supply versus smaller populations with more plentiful prey available, rather than their north/south distributions. More work is needed to better understand the factors that influence size.

Type material examined.

Holotype ♂ (00162206) (USNM): UNITED STATES: Florida: Duval Co.: Jacksonville, 30.33194°N, 81.65583°W, 23 Jul 1926, E. D. Ball.

Other specimens examined.

UNITED STATES:Connecticut:New London Co.: Stonington Township, Barn Island, 41.335°N, 71.906°W, 11 Aug 1971, R.T. and J. C. Schuh, 9 ♂♂ (00095349, 00165938 - 00165945), 11 ♀♀ (00095350, 00165946 - 00165955) (AMNH), 1 ♂ (00138679) (USNM) (all brachypterous, except two macropterous ♀♀). Tolland Co.: Mansfield Center, 41.76528°N, 72.19861°W, 84 m, 01 Aug 1956, J. A. Slater, 1 ♀ (00166063) (AMNH) (brachypterous). Florida:Brevard Co.: Titusville, 28.61194°N, 80.80778°W, 29 Apr 1952, collector unknown, 1 ♂ (00161887) (USNM) (macropterous). Duval Co.: CR-105, 1 km W. of Dunn Creek, S. of Eastport, 03 Apr 2004, A. G. Wheeler, Jr., ex Spartina patens (Poaceae), 1 ♀ (00161882) (USNM) (brachypterous). Miami-Dade Co.: Biscayne Bay, 25.5747°N, 80.3112°W, 1700, Mrs. A.T. Slosson, 2 ♂♂ (00165956, 00165957) (AMNH) (brachypterous). Louisiana: Tangipahoa Parish: Hammond, 22 June 1948, E. L. Todd, 1 ♂, 1 ♀ (AMNH) (macropterous). New Jersey:Ocean Co.: 2 mi. E. of Manahawkin off Stafford Ave., 20 Jul 1976, collector unknown, Distichlis spicata ( Poaceae ), 5 ♂♂ (00161870, 00161877 - 00161878, 00161880, 00161886), 2 ♀♀ (00161879, 00161881) (USNM) (all brachypterous). Tuckerton, 39.60305°N, 74.34027°W, 4 m, 01 Aug 2002, R.F. Denno & D. Lewis, Spartina patens ( Poaceae ), 7 ♂♂ (00161865 - 00161868, 00161872, 00161874 - 00161875), 4 ♀♀ (00161869, 00161871, 00161873, 00161876) (USNM) (all brachypterous). South Carolina:Colleton Co.: Bear Island Wildlife Management Area, near Mary’s House Pond, 03 May 2003, A. G. Wheeler, Jr., ex Spartina patens ( Poaceae ), 1 ♀ (00161883) (USNM (brachypterous). CR-26, 0.3 km N. of Ashepoo River, N. of Bennetts Pt., 03 May 2003, A. G. Wheeler, Jr., ex Spartina bakeri ( Poaceae ), 1 ♀ (00161885) (USNM) (brachypterous). CR-26, 1.1 km W. of Bennetts Point, 04 May 2003, A. G. Wheeler, Jr., Spartina bakeri ( Poaceae ), 1 ♂ (macropterous), 1 ♀ (00161889) (brachypterous) (USNM). Texas:Jefferson Co.: J.D. Murphree Wildlife Management Area, near Lost Lake, 29.78111°N, 93.97333°W, 26 May 1994, R. Vogtsberger, taken by mosquito dipper cup, 1 ♂ (00161888) (USNM) (brachypterous). Virginia: Mecklenburg Co.: Elm Hill WMA, Clyde’s Pond, 11-29 May 1995, VMNH survey, 4 ♂♂ (VMNH). City of Virginia Beach: Dam Neck Naval Base, dune DF site, 25 June 1991, K. A. Buhlmann, 1 ♂ (V MNH).