Agapostemon (Agapostemon) texanus Cresson, 1872

Portman, Zachary M., Arduser, Mike, Powley, Mary E. & Cariveau, Daniel P., 2024, Taxonomy of Agapostemon angelicus and the A. texanus species complex (Hymenoptera, Halictidae) in the United States, European Journal of Taxonomy 958, pp. 203-241 : 232-235

Agapostemon (Agapostemon) texanus Cresson, 1872

Figs 1C–D , 4C, F , 5I–J, M , 6C–D , 8A, D

Original reference

Agapostemon texanus Cresson, 1872: 255 ♀. Lectotype ♀ (designated by Cresson 1916), Texas. Deposited at ANSP, type No. 2111. Images examined.

Synonymy

Agapostemon texanus iowensis Cockerell 1910a: 363 ♀ (syn. under A. texanus s. lat. by Sandhouse 1936, syn. under A. texanus s. lat. by Roberts 1972). Holotype ♀, Ames, Iowa, 1899, Wilmon Newell leg., deposited in USNM [no. 536746]. Images of type examined. Online record: http://n 2t.net/ark:/65665/3e1e30975-da9e-4c6e-b300-700d7cbad4ee

Taxonomy and references

Agapostemon texanus – Dalla Torre 1896: 97 (catalog). — Robertson 1897: 328 [in part, mixed with A. subtilior and A. angelicus ] (description, range); 1902: 246 (key). — Cockerell 1898: 27 (taxonomy). — Crawford 1901: 160 [in part, mixed with A. subtilior and potentially A. angelicus ] (key, taxonomy). — Vachal 1903: 94 [in part, likely mixed with A. angelicus ] (key, description). — Cresson 1916: 109 (lectotype designation). — Cockerell 1927: 157 [likely mixed with A. subtilior ] (key, records). — Sandhouse 1936: 82 [in part, combined with A. subtilior ] (key, diagnosis, distribution). — Roberts 1972: 533 [in part, mixed with A. subtilior ] (key, diagnosis, distribution). — Hurd 1979: 1953 [in part, combined with A. subtilior ] (catalog). — Moure & Hurd 1987: 190 [in part, combined with A. subtilior ] (catalog). — Portman et al. 2022: 117 [in part, combined with A. subtilior s. s.] (key, diagnosis).

Agapostemon texanus texanus – Michener 1951: 1124 [in part, combined with A. subtilior ] (catalog). — Mitchell 1960: 454 [in part, combined with A. subtilior ] (key, description, distribution, floral records).

Diagnosis

Female A. texanus can be diagnosed from the other doubly-punctate species by the extremely coarse genal striae ( Fig. 1C–D ). In contrast to the weak or moderately coarse genal striae of A. angelicus and A. subtilior ( Fig. 1A–B ), the genal striae of A. texanus are very coarse and quite deep, with the ridges rather wavy and irregular, to the point where it is difficult to see the bottom between the ridges ( Fig. 1D ). In addition, A. texanus have around 5–8 genal striae that end along the longitudinal part of the hypostomal carina ( Fig. 1C ), whereas the genal striae of A. angelicus and A. texanus curve away from the longitudinal part of the hypostomal carina and towards the lateral part of the hypostomal carina ( Fig. 1A–B ). Females of A. texanus can be further recognized by the very closely punctate metasoma, which has contiguous punctures on the terga ( Fig. 4 C, F ), and they have a densely punctate and dull scutum (though this character intergrades with A. subtilior and A. angelicus ). They can be further separated from A. subtilior by the shape of the apex of the clypeus, which is flat down to the apex in A. texanus , compared to curved over at the apex in A. subtilior ( Fig. 2D ).

With their large size and coarsely striate gena, A. texanus females are also similar to those of A. splendens , but A. texanus lacks the heavily dusky wings found in A. splendens . In addition, A. splendens lacks the doubly-punctate scutum.

Male A. texanus can be recognized from those of A. subtilior and A. angelicus by the combination of the moderately inflated hind femur ( Fig. 5I ), and the hind tibia with both a dark mark on the anterior face ( Fig. 5I ) AND an extensive dark mark on the posterior face ( Fig. 5J ). They are similar to A. subtilior but can be separated by the more extensive dark mark on the posterior face of the hind tibia ( Fig. 5J ), which takes up at least half the segment in A. texanus but takes up at most half the segment in A. subtilior ( Fig. 5H ). In addition, the genitalia of A. texanus have the basal stylus shorter and more evenly curved ( Fig. 6D , black arrow), whereas A. subtilior have the basal stylus longer and with a more abrupt curve closer to the apex ( Fig. 6E , black arrow). Finally, males of A. texanus have the hind basitarsus more completely fused to the following segment ( Fig. 5M ) than those of A. subtilior ( Fig. 5L ) and A. angelicus ( Fig. 5K ), though this is subtle. Males of A. texanus are also similar to males of A. angelicus , but A. texanus have a dark mark anteriorly on the hind tibia ( Fig. 5I ), which A. angelicus lack ( Fig. 5A ), and A. texanus have a distinctly more inflated hind femur than A. angelicus . The genitalia of these two species are also quite distinct, with A. texanus having a narrow, slender basal stylus and a larger medial plate ( Fig. 6C ), whereas A. angelicus have a thickened basal stylus and a smaller medial plate ( Fig. 6A ).

Material examined

USA – ARKANSAS – Monroe Co. • (34.971 -91.3029): 1 ♀; 20 Jul. 2016; PL Stephenson leg.; MAPC; 5 ♀♀; 11 Aug. 2016; PL Stephenson leg.; MAPC • Hallum Cemetery Rd (34.8571 -91.2376): 6 ♀♀; 2–9 Aug. 2016; PL Stephenson leg.; MAPC . – Sebastian Co. • Fort Chaffee park area nr Wells Lake / Roberts Rd : 1 ♀; 7 Aug. 2004; Arduser leg.; Cirsium discolor ; MAPC . – Woodruff Co. • Cache [River] National Wildlife Refuge (35.1186 -91.1612): 1 ♀; 11 Aug. 2016; PL Stephenson leg.; MAPC • Cache [River] National Wildlife Refuge (35.1262 -91.2809): 3 ♀♀; 9 Aug. 2016; PL Stephenson leg.; MAPC; 1 ♀; 2 Sep. 2016; PL Stephenson leg.; MAPC . – IOWA – Story Co. • Ames : 1 ♀ ( A. texanus iowensis holotype); day and month unknown 1899; W Newell leg.; NMNH . – Woodbury Co. • Souix City : 1 ♂; Aug. 1939; CN Ainslie leg.; swept lawn; UMSP .– KANSAS – Anderson Co. • (38.098485 -95.4173): 1 ♂; 21 Jun. 2018; A Morphew leg.; AMC . – Bourbon Co. • (37.832724 -94.8391): 1 ♂; 19 Jun. 2018; A Morphew leg.; AMC . – Coffey Co. • (38.328091 -95.6975): 1 ♂; 9 Jul. 2018; A Morphew leg.; AMC – Douglas Co. • 2 ♀♀; 7 Jul. 1920; William E Hoffmann leg.; Apocynun cannabinum ; UMSP; 1 ♂; day and month unknown 1920; William E Hoffmann leg.; A. cannabinum ; UMSP . – Gove Co. • (38.97286 -100.536): 1 ♂; 22 Jul. 2019; A Morphew leg.; AMC . – Hodgeman Co. • (38.100843 -98.6435): 1 ♂; 24 Jul. 2018; A Morphew leg.; AMC . – Logan Co. • (39.0784 -100.9095): 2 ♂♂; 18 Jun. 2018; A Morphew leg.; AMC . – Rice Co. • (38.177082 -98.2506): 1 ♂; 29 Jun. 2018; A Morphew leg.; AMC . – Thomas Co. • (39.935156 -101.180707): 1 ♂; 2 Jul. 2019; A Morphew leg.; AMC . – Wallace Co. • (38.941923 -101.792): 1 ♂; 10 Jul. 2019; A Morphew leg.; AMC . – MINNESOTA – Hubbard Co. • Itasca Park : 1 ♂; 16 Jul. 1936; collector unknown; UMSP . – Jackson Co. • Graham Creek WMA (43.7823 -95.4131): 1 ♀; 5 Jun. 2019; ED, LN leg.; bee bowls; CNBL • Graham Creek WMA (43.78235 -95.4131): 1 ♀; 2 Jul. 2021; WB, EB leg.; bee bowl; CNBL . – Martin Co. • (43.5495 -94.7961): 3 ♀♀; 7 Aug. 2019; SG, MK leg.; bee bowls; CNBL . – Murray Co. • (43.8573 -95.594): 1 ♀; 25 Jun. 2019; MK, LN leg.; bee bowls; CNBL • (44.0709 -95.5718): 1 ♀; 22 Jul. 2019; SG, MK leg.; bee bowls; CNBL • (44.07093 -95.5718): 1 ♀; 2 Jul. 2021; LS, LF leg.; bee bowl; CNBL . – Nobles Co. • (43.52333 -95.7276): 1 ♀; 27 Jul. 2022; WL, MM leg.; bowl; CNBL . – Swift Co. • Chippewa TNC (45.15452 -96.0086): 1 ♀; 21 Jun. 2018; M Rancour leg.; bowl; UMSP . – Yellow Medicine Co. • (44.68504 -96.3092): 1 ♀; 28 Jun. 2022; LT, MM leg.; bowl; CNBL . – MISSOURI – Barry Co. • Roaring River State Park , Chute Ridge glade: 1 ♀, 4 ♂♂; 3 Jul. 2018; K McCarty leg.; Silphium laciniatum ; MAPC . – Cedar Co. • Wah-Kon-Tah Prairie , house (37.8973 -93.9935): 1 ♀; 13–14 Jul. 2008; RP Jean leg.; blue bowls; MAPC . – Laclede Co. • Bennett Springs savanna ( TNC): 2 ♀♀; 25 Jul. 2018; K McCarty leg.; Helianthus hirsutus ; MAPC . – Ray Co. • Big Muddy Nat’l Wildlife Refuge , Jackass Bend , old field: 1 ♀; 22 May 2013; W Watkins leg.; MAPC . – Saline Co. • Van Meter State Park : 1 ♂; 10 Aug. 2020; K McCarty leg.; Silphium perfoliatum ; MAPC . – Shannon Co. • Ozark Nat’l Scenic Riverways above Jertail Landing (37.2297 -91.3139): 1 ♂; 29 Sep. 2005; collector unknown; Aster pilosus ; MAPC . – St. Clair Co. • Shell-Osage Conservation Area (37.9667 -94.0449): 13 ♀♀, 1 ♂; 22 Jul. 2014; Arduser, Jean leg.; malaise trap; MAPC . – NEBRASKA – Dodge Co. • North Bend : 1 ♂; 27 Aug. 1959; TM Peters leg.; UMSP . – Hall Co. • Platte River Prairies ( TNC), Derr house , 50 yards into prairie reconstruction (40.7334 -98.579): 3 ♀♀; 5 Aug. 2013; Arduser leg.; bowls; MAPC • Platte River Prairies ( TNC), Derr house , south lawn (40.7336 -98.5786): 2 ♀♀; 5 Aug. 2013; Arduser leg.; bowls; MAPC • Platte River Prairies ( TNC), Studnicka Tract, NE (40.7309 -98.5957): 1 ♀; 5 Aug. 2013; Arduser, Helzer, Stine leg.; Silphium integrifolium ; MAPC • Platte River Prairies ( TNC), sandhills remnant (40.7287 -98.5763): 1 ♂; 9 Aug. 2013; Arduser leg.; Helianthus petiolaris ; MAPC . – OKLAHOMA – Caddo Co. • 1 mi. N of Hinton on Hwy 281 (35.518 -98.3502): 1 ♀; 15 Aug. 1995; Arduser, Stevens leg.; Prionopsis ciliata ; MAPC • Red Rock Canyon State Park (35.4583 -98.3528): 2 ♀♀; 15 Aug. 1995; Arduser leg.; Chamaecrista fasciculata ; MAPC . – Comanche Co. • Wichita Mtns NWR , Charon’s Garden Trail , south portion (34.7091 -98.7317): 1 ♀; 5 May 2012; Arduser leg.; Opuntia engelmanni ; MAPC . – Ellis Co. • Four Canyon Preserve ( TNC), head of Horse Canyon (36.0195 -99.4631): 1 ♀; 7 Jun. 2009; Arduser leg.; Cornus drummondi ; MAPC . – TEXAS – Brazos Co. • 1 ♂; date unknown; N Banks leg.; MCZ . – Burnet Co. • Inks Lake St. Park : 1 ♀; 18 Apr. 1962; TM Peters, FW Stahr leg.; UMSP . – Colorado Co. • Rock Island : 1 ♀; 31 May 1922; Grace O Wiley leg.; UMSP . – Dallas Co. • 1 ♀; 9 May 1948; Barr leg.; UMSP; 1 ♀; 15 May 1948; Barr leg.; UMSP • Dallas: 3 ♀♀ (paralectotypes); date unknown; collector unknown; MCZ . – Eastland Co. • 2 ♀♀; 23 May 1921; Grace O Wiley leg.; UMSP; 1 ♂; 8 Jun. 1921; Grace O Wiley leg.; UMSP; 1 ♂; 12 Jun. 1921; Grace O Wiley leg.; UMSP; 1 ♂; 14 Jun. 1921; Grace O Wiley leg.; UMSP . – Kleberg Co. • Kingsville : 1 ♀; date unknown; CT Reed leg.; MCZ . – Lee Co. • 1 ♂; date unknown; Birkmann leg.; MCZ • Fedor : 1 ♂; 3 Sep. 1897; G Birkmann leg.; MCZ; 1 ♂; 11 Sep. 1897; G Birkmann leg.; MCZ; 1 ♀; day and month unknown 1897; G Birkmann leg.; MCZ; 1 ♀; 24 Apr. 1899; G Birkmann leg.; MCZ; 1 ♂; 31 May 1899; G Birkmann leg.; MCZ; 2 ♂♂; 19 Jun. 1899; G Birkmann leg.; MCZ; 1 ♀; 5 May 1901; G Birkmann leg.; MCZ; 1 ♂; 7 Jun. 1901; G Birkmann leg.; MCZ; 1 ♂; 14 Jun. 1901; G Birkmann leg.; MCZ; 1 ♀; 30 Jun. 1902; G Birkmann leg.; MCZ; 1 ♀; 13 Mar. 1903; G Birkmann leg.; MCZ; 1 ♀; 13 Mar. 1903; collector unknown; MCZ; 2 ♀♀; 24 Feb. 1904; G Birkmann leg.; MCZ; 2 ♀♀; 19 Mar. 1904; G Birkmann leg.; MCZ; 1 ♀; 5 Jun. 1904; G Birkmann leg.; MCZ . – McLennan Co. • Waco : 1 ♀; date unknown; collector unknown; MCZ . – Palo Pinto Co. • 3 mi. N of Brazos R. on Rt. 281: 1 ♂; 12 Nov. 1990; V Scott, M Arduser leg.; Aster sp. ; MAPC . – Parker Co. • 1 ♀; 30 May 1948; Barr leg.; UMSP . – Travis Co. • Lake Travis : 1 ♀; 19 Sep. 1982; collector unknown; UMSP . – Unknown Co. • 2 ♀♀; date unknown; collector unknown; MCZ .

Remarks

We define A. texanus in a much narrower sense than previous revisers, because A. texanus , as defined by Sandhouse (1936) and especially Roberts (1972), was a cryptic species complex. Most of what was previously considered A. texanus is now the newly reinstated A. subtilior . It is surprising that Roberts (1972) did not recognize that A. subtilior and A. texanus were distinct, given that differences in the size of the genal striae in the females is a character that Roberts (1972) used to separate females of other Agapostemon species. We can only speculate that Roberts (1972) was so stymied by attempts to separate A. angelicus females that it led to an over-reliance on male characters to define species boundaries, and while differences in male genitalia between A. texanus s. s. and A. subtilior are distinct, they are subtle enough that they could easily be overlooked.

There is still more work needed on the A. texanus species complex, as Roberts (1972) considered the range of A. texanus to extend down through Mexico and into Guatemala and Costa Rica. However, for this work, ZP examined 3 males and 5 females from various locations in Central and Southern Mexico, and a series of 3 females and 1 male from Guatemala. All of these specimens bear determination labels from Roberts in 1965 as A. texanus . However, none of these specimens are referable to A texanus . In particular, the females lack the strong genal striations of A. texanus s. s., and the dissected genitalia of the male were different, resembling more those of A. subtilior (though other characters, such as the hind basitarsus shape, do not match A. subtilior ). The possibility that the Mexican members of the A. texanus species complex could extend up into the southern US (especially southern Texas) means that identification in that region should be approached with caution.

Ecology

The nesting biology of A. texanus from Kansas is reported in Roberts (1969); this species is solitary, ground nesting, and polylectic.

Distribution

Agapostemon texanus s. s. appears to be a largely tallgrass and mixed prairie species, ranging from Minnesota in the North to Texas in the South. We have confirmed specimens from: AR, IA, KS, MN, MO, NE, OK, SD, TX. Agapostemon texanus is a relatively uncommon species, particularly compared to A. angelicus and A. subtilior .

Figures

Fig. 1. Genal striae of females. A. Agapostemon angelicus Cockerell, 1924. B. A. subtilior Cockerell, 1898. C. A. texanusCresson, 1872 s. s. D. Zoomed-in view ofA. texanuss. s. striae, image of paralectotype (MCZENT548), provided by Zoe Flores and Crystal Maier of the MCZ. Scale bars: 1 mm.

Fig. 4. Female metasoma comparison. A. Agapostemon angelicus Cockerell, 1924. B. A. subtilior Cockerell, 1898. C. A. texanus Cresson, 1872 s. s. D. A. angelicus, T1 and T2, with red arrow pointing to lateral areas basal to premarginal line with denser punctures. E. A. subtilior, T1 and T2, with red arrow pointing to area of sparser punctures. F. A. texanus s. s., T1 and T2, with red arrow pointing to area of denser punctures. Scale bars: 1 mm.

Fig. 5. Male hind legs. A. Agapostemon angelicus Cockerell, 1924, anterior view. B. A. angelicus, posterior view. C. A. subtilior Cockerell, 1898, lightest color, anterior view. D. A. subtilior, lightest color, posterior view. E. A. subtilior, anterior view. F. A. subtilior, posterior view. G. A. subtilior, dark, anterior view. H. A. subtilior, dark, posterior view. I. A. texanus Cresson, 1872, anterior view. J. A. texanus, posterior view. K. A. angelicus, basitarsus. L. A. subtilior, basitarsus. M. A. texanus, basitarsus. Scale bars: A–J = 1 mm; K–M = 500 µm.

Fig. 6. Apical view of male genitalia. A. Agapostemon angelicus Cockerell, 1924. B. A. subtilior Cockerell, 1898. C. A. texanus Cresson, 1872 s. s. D. A. texanus s. s., zoomed in with black arrow pointing to more evenly curved lower stylus. E. A. subtilior zoomed in with black arrow pointing to more laterally extending lower stylus. Scale bars: 500 µm.

Fig. 8. Range maps of specimens examined by the authors. A. Agapostemon texanus Cresson, 1872 s. s. B. Distribution of A. angelicus Cockerell, 1924 in Minnesota. C. Distribution of A. subtilior Cockerell, 1898 in Minnesota. D. Distribution of A. texanus s. s. in Minnesota.

Fig. 2. Comparison of Agapostemon angelicus Cockerell, 1924 and A. subtilior Cockerell, 1898, female head and clypeus. A. A. angelicus, face. B. A. angelicus, apex of clypeus. C. A. subtilior, face. D. A. subtilior, apex of clypeus. Scale bars: A, C = 1 mm; B, D = 500 µm.