Charles C. Porter.
Ecology, Zoogeography and Taxonomy of the Lower Rio Grande Valley Mesostenines (Hymenoptera, Ichneumonidae).
Psyche 84:28-91, 1977.

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ECOLOGY, ZOOGEOGRAPHY AND TAXONOMY OF THE LOWER RIO GRANDE VALLEY MESOSTENINES
(HYMENOPTERA, ICHNEUMONIDAE)
BY CHARLES C. PORTER'
Department of Biological Sciences, Fordham University Bronx, N.Y. 10458
INTRODUCTION
This study analyzes results of five years' fieldwork with net and Malaise Traps on mesostenine ichneumonids of semiarid subtropi- cal scrub and moist gallery woods habitats in the Lower Rio Grande Valley of south Texas. It lists 18 genera and 35 species. The genus Bicristella and the species Trachysphyrus mesorufus, Cryptanura lamentaria, and Lymeon leucosoma are recorded for the first time from the United States. Cryptanura vallis Mesostenus opuntiae, Bricristella texana, Diapetimorpha sphenos, D. aspila, and D. pareia are described as new. The zoogeographic relationships, phaenol- ogy, and habitat preferences of each taxon are recorded and con- clusions are adduced as to distributional patterns, annual cycles, habitat selection, and diversity of the entire south Texas mesoste- nine fauna. The south Texas fauna also is compared with meso- stenine communities of other semiarid parts of the Neotropics, such as the Peruvian Coastal Desert and the northwest Argentine Sub- andino, and all these relict or marginal xerophilic faunas are dis- cussed with regard to their origin in wet forest centers of ichneu- monid radiation.
Major support for this research was provided in 1976-'77 by a National Science Foundation Grant (DEB 75-22426) and during 1973-'75 by grants from the Committee for Research and Explora- tion of the National Geographic Society. Mr. David Riskind and Mr. Sim Oefinger, Jr. of the Texas Parks and Wildlife Department issued permits for insect collecting in the Bentsen Rio Grande Valley State Park. At Bentsen Park, Mr. Reynaldo Ortiz (Superintendent) 'Research Associate, Florida State Collection of Arthropods, Florida Department of Agriculture and Consumer Services, Gainesville, Florida 32602. Manuscript received by the editor, May 24, 1977 Pu&e M:28-91 (1977). hup Ytpsychu einclub orgt8.UM-028 html



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19771 Porter - hfesostenines 29
and Mr. Antonio Salinas (Park Ranger 3) maintained the Malaise Trap used in my 1976 survey and provided cordial assistance on all my visits to the park. Mrs. Vivian Thacker, as trustee of the Valley Botanical Garden, facilitated collecting in that small but important island of natural vegetation. My father, Mr. Carroll B. Porter, also assisted in the Malaise project and in many other ways. Mr. Charles W. Calmbacher of Fordham University prepared and labeled most of the Malaise samples from Bentsen Park. Finally, Dr. Henry K. Townes of the American Entomological Institute loaned several homotypes which helped resolve crucial taxonomic problems. I
MATERIALS AND METHODS
Hand collecting with a strong but light net obtained 63% of the 679 specimens captured between May 1973 and March 1977 for use in this study. Sweeping undergrowth yielded numerous mesoste- nines but many others were netted individually in flight from foli- age. Periods annually available for fieldwork included 25 August to 9 September, 18 December to 25 January, 11-21 March (1-8 April in 1975) and 16 May to 10 June. I was in the field 7 days a week and 6-8 hours per day during all visits to south Texas. To obtain a more comprehensive picture of mesostenine diversity than would have been possible by hand collecting alone, I employed two Malaise Traps during this research. The first was installed at the Valley Botanical Garden in a Celtis lindheimeri-C. pallida thicket and functioned from September 1973 until March 1974 but was stolen in April 1974. The second was set up under a large Pithecel- lobium flexicaule in deep woods near a lake at the Bentsen Rio Grande Valley State Park and, having already furnished a complete series of samples for 1976, continues to operate during 1977. In both traps, a pint mason jar filled with 70% isopropyl alcohol (commer- cial rubbing alcohol) was used as the collecting recipient. The trap at the Botanical Garden was changed once a month but I was able to arrange for twice monthly curating of the Bentsen Park trap. Both Malaise Traps were of the "light weight" variety, as perfected by Dr. Henry K. Townes (Townes, 1972, p. 239-247). The Lower Rio Grande Valley is an alluvial plain that extends along the Rio Grande River for about 120 km. in Hidalgo and



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30 Psyche [March
Cameron counties of Texas and the Mexican state of Tamaulipas, beginning on the east at the Gulf of Mexico and ending approx- mately at the level of Mission, Texas on the west. Nowhere is this Valley much more than 25 or 30 km. wide either north or south of the river. It constitutes an island of fertile soil, relatively high humidity, and comparatively lush vegetation surrounded landward on all sides by desert scrub.
Because of its latitude (26 degrees N.) and proximity to the Gulf, the Valley experiences an extremely mild temperature regimen. The average yearly maximum at Brownsville is 28 degrees C. and the minimum 18.3 degrees C. Summer highs rarely go above 40 degrees C. and the average daily range for July at Brownsville is 33.6 de- grees C. to 24.2 degrees C. On the other hand, most winters have only two or three frosts during which the temperature normally does not fall below -3 to -4 degrees C., although the record low for Brownsville is -1 1 degrees C. (registered in February 1899). The averas daily range for January at Brownsville is 21.4 degrees C. to 11.2 degrees C. and such temperatures occur quite consistently throughout the Valley in winter, although from November to March warm periods frequently are interrupted by cold fronts that bring 4-10 day stretches of cloudy weather when the temperature stays between about 4 and 10 degrees C.
Precipitation in the Valley is rather scant, averaging 669 mm. per year at Brownsville. It occurs in winter as protracted fine drizzle, in spring, summer, and fall as occasional thunderstorms, and sometimes in late summer and early fall as torrential inunda- tions that accompany inland-moving hurricanes. September, with an average of 124.8 mm. is the wettest month while March, with 26 mm., is the driest. Although long-term figures suggest fairly even rainfall distribution, there is actually great variation from month to month and from year to year. Protracted droughts are common but some years may have more than 1000 mm. of rain. Vegetation of the Valley ranges from desert scrub to humid sub- tropical woodlands best developed along the Rio Grande and in the vicinity of water holes. The south Texas flora resembles that which grows in many other semi-arid environments from Mexico to Argentina. Some of the more conspicuous angiosperm genera are Acacia, Baccharis, Bumelia, Celtis. Cercidium, Condalia, Ery- thrina, Opuntia, Parkinsonia, Prosopis, Salix, TMandsia, and Xan- thoxylum. This same element occurs also in the ecologically sim-



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19771 Porter - Mesostenines 3 1
ilar Argentine Chaco at the austral extreme of the Neotropics. Almost all my fieldwork on Valley mesostenines was done in the 500 acre Bentsen Park near Mission and the 20 acre Valley Botan- ical Garden at McAllen. Otherwise, except for the Santa Ana Na- tional Wildlife Refuge near Alamo, most natural vegetation has been extirpated from the Valley and replaced by citrus groves, truck farms, sugar-cane fields and other agricultural systems. The Valley Botanical Garden is about
16 km. from the Rio
Grande and thus lacks gallery forest and other really humid asso- ciations but offers a sample of scrub communities and moderately humid woods.
Here the most abundant or conspicuous larger plants are: Acacia greggii (rare), A. farnesiana (common), Baccharis sp. (common), Bumelia celastrina (rare), Celtis lindheimeri (com- mon), C. pallida (common), Cercidium floridurn (rare), Condalia obovata (common), C. obtusifolia (common), Ehretia anacua (com- mon), Forestiera texana (rare), Karwinskia humboldtiana (com- mon), Leucaena pulverulenta (scarce), Moms rubra (rare), Opuntia sp. (common), Parkinsonia aculeata (common), Phaulothamnus spinescens (rare), Pithecellobium flexicaule (rare), Porlieria ungus- tifolia (rare), Prosopis julzjlora (common), Sabal texana (rare), Salix nigra (common), Serjania sp. (common), and Xanthoxylum fagara (scarce). Within its 20 acres, the Botanical Garden contains several more or less distinct associations. Dry areas are dominated by Prosopis juhflora and Opuntia sp. with Condalia obtusifolia and Parkinsonia aculeata often common also. Moderately dry habitats have at least some of the foregoing species along with Condalia obovata, Celtis pallida, Baccharis sp., and Bumelia cel- astrina. Moderately humid sites usually are dominated by Celtis lindheimeri in the tree stratum, C. pallida in the shrub layer, and by Serjania vines at ground level. They also may contain the small tree Ehretia anacua, the large shrub Xanthoxylum fagara, and the small shrub Karwinskia humboldtiana.
The large trees Leucaena
pulverulenta and Salix nigra also occur in the Garden but only near ponds and irrigation canals. Finally, some abandoned farm- lands near the Garden support open Acacia farnesiana woods with a monotonous undergrowth of tall grasses. The Bentsen Park is much larger and floristically more varied than the Botanical Garden. Only Sabal texana occurs in the Gar- den but not at Bentsen, while Amyris texana (common), Fraxinus berlandieriana (common), Mimosa berlandieriana (moderately com-



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32 Psyche [March
mon), Sapihdus drummondii (scarce), Tillandsia usneoides (com- mon), and Ulmus crassifolia (common) have been found exclusively in the State Park. In addition to all plant associations described for the Botanical Garden, Bentsen Park supports distinctive gallery forest and water hole communities.
Lush woods along the Rio
Grande contain Salix nigra, Fraxinus berlandieriana, Celtis lind- heimeri, Mimosa belandieriana, Acacia farnesiana and a profli- gate ground cover of Serjania vines. Even more luxuriant is the flora near a permanent water hole, which includes huge examples of Fraxinus, Ulmus, Leucaena, and Ehretia, some Pithecellobium and Sapindus, numerous Xanthoxylum, some Mimosa, abundant Amyris, and an impressive epiphyton of Tillandsia usneoides on many larger trees. Other dark, damp zones in Bentsen Park are dominated by Pithecellobium flexicaule.
Climatically and floristically, the Valley thus emerges as de- cidedly subtropical and the same is true for most of its fauna, from ichneumonid wasps and diurnal Lepidoptera to reptiles and birds. Indeed, south Texas harbors the richest Neotropic biota of any part of the United States.
Mesostenines are one of the largest groups in the Family Ichneu- monidae and inhabit all continents, having radiated n~assively in both tropical and temperate regions. They parasitize the pupae of many Lepidoptera as well as of some Coleoptera, Neuroptera, Dip- tera, and certain Hymenoptera. Most species are taxonomically catholic in host selection, each one being attracted to diverse kinds of pupae in a restricted spatial niche (leaf rolls, ground litter, stems, tunnels in tree trunks, etc.) rather than choosing victims from anlong one particular genus or even family of insects. Like most ichneun~onids, n~esostenines prefer humid forest habi- tats, so that in the New World they are best represented in the North American Temperate Deciduous Forest and again in various kinds of Latin American subtropical and tropical wet forests. The comparatively dry Lower Rio Grande Valleythus has a rather de- pauperate mesostenine fauna, whose relations are principally but not exclusively Neotropic.
Listed below together with relevant ecological, zoogeographic and taxonomic data are the 18 genera and 35 species of Mesostenini so far recorded from the Lower Rio Grande Valley.



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19771 Porter - Mesostenines 33
1. Gambrus bituminosus Cushnian
SPECIMENS EXAMINED: 1 female, Bentsen Park, 31 XI1 '76. HABITAT: Weeds in sandy area at edge of field not far froni Ria Grande.
DISTRIBUTION: Mass., N.Y., N.J., Ill., Minn., Ga., La., Cal., new for Texas.
PHAENOLOGY: Summer in north, winter in south. 2. Gambrus ultimus (Cresson)
SPECIMENS EXAMINED: 6 females, 2 males: BENTSEN PARK (Net: 2 females, 13 I '76; 1 female, 19 I '76; 1 female, 29 XI1 '76; Malaise: 1 male, 16 X '76); BOTANICAL GARDEN (Net: 1 feniale, 12-21 I '76; 1 female, 17-24 111 '74; 1 male, 18 111 '74). HABITAT: Serjania vine tangles under shade of Celtis lindheimeri and other large trees.
DISTRIBUTION: Continental U.S.
PHAENOLOGY: Flies in Valley from October to March with peak in January (4 of 8 collections). Active in north froni April to October.
3. Trychosis subgracilis (Cresson)
SPECIMENS EXAMINED: 1 feniale, 2 niales: BENTSEN PARK (Net: 1 feniale, 23 I '76; Malaise: 2 niales, 15-30 IV '76). HABITAT: Serjania vines in gallery woods beneath Celtis lind- heimeri and Salix nigra; entered trap beneath Pithecellobiumflexi- caule.
DISTRIBUTION: Eastern U.S.; first record for Valley. PHAENOLOGY: January to April in Valley; April to August in northern states.
4. Trachysphyrus mesorufus (Cushnian)
(Fig. 6)
FEMALE: Color: scape black with a broad, nearly percurrent white bar below and brown on dorsal rim; pedicel black; flagel- lum black with a ventrally inconiplete white band on segments 5-1 1; head and mesosoma black with white markings as follows: basal 21 3 of the otherwise somewhat brownish mandibles; blotch covering niost of clypeus; most of face except for a large area be-



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34 Psyche [March
tween and below antenna1 sockets and a pair of submedian blotches above clypeus that are narrowly confluent mesad and which con- nect laterally with a large black area in anterior 1 /4 of malar space; very broad orbital ring interrupted only in malar space and ventro- posteriorly much expanded and almost reaching hypostomal ca- rina; blotch on apical 1 /2 of propleuron; very broad anterior mar- gin of pronotum; very broad humeral margin of pronotum; pair of longitudinal blotches on about median 314 of mesoscutum in position of notauli; scutellum; most of postscutellum; tegula; axil- lary sclerites; subalarum; large anterio-median blotch on mesepi- sternum just behind prepectal carina; broad stripe in anterior 213 of sternaulus; large blotch in lower hind corner of mesepisternum; mesepimeron pure white on dorsal 1 /4 and more brownish ventrad; most of dorsal metapleuron; large, dorso-posterior blotch on apical 112 of lower metapleuron; and a pair of very broad blotches occu- pying all but median 113 of hind face of propodeum from cristae to apical margin; first gastric tergite red with a broad white band covering apical 112 of postpetiole; second tergite black with red- dish staining baso-laterally and a broad white subapical band; and following tergites black with broad white apical bands; fore and mid legs ferruginous with tarsus duller and fifth tarsomere dusky, trochanter white with brownish above, and coxa white with a small reddish spot above near apex and more broadly marked with dark red to blackish below; hind leg with coxa red except for a small white blotch above at base, trochanter and trochantellus red, femur more ferruginous, tibia dull ferruginous with a slight dusky tinge on base and blackish on about apical 1 / 10, first tarsomere brown- ish black with white briefly throughout on apex and whitish below on apical 112, second tarsomere white, third white with a dusky area above subapically, fourth black with a little whitish on base and fifth black; wings hyaline.
Structurally, mesorufus much resembles the Floridian T. weemsi (Porter, 1974, p. 331-335), from which it may be distinguished by most of the characters listed below:
Length of fore wing: 6.1 mm. Pronotum: dorsal margin moder- ately swollen. Mesoscutum: notauli very weak but traceable about 2/ 3 the length of mesoscutum. Mesopleuron: speculum swollen, smooth and shining with only a few large punctures peripherally; surface otherwise almost uniformly with strong, reticulate wrink-



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19771 Porter - Mesostenines 35
ling which obscures its punctures. Wing venation: radial cell 3.3 as long as wide; second abscissa of radius 0.7 as long as first inter- cubitus; disco-cubitus broadly angled with a long and conspicuous ramellus at angulation; upper part of nervellus 3.5 as long as lower. First gastric tergite: post-petiole 1.7 as wide apically as long from spiracle to apex. Second tergite: a little duller and more densely punctate than in weernsi. Ovipositor: sheathed portion 0.34 as long as fore wing; nodus distinct, with a very shallow and broad notch; dorsal valve on tip with a gradual, straight taper between notch and apex; tip 0.17 as high at notch as long from notch to apex. MALE: Unknown.
SPECIMENS EXAMINED: 1 female, Botanical Garden, 2 April 1975. DISCUSSION: As noted above, rnesorufus closely resembles the Floridian T. weemsi except in color pattern and in some subtle structural characters, whose real value only will be established when more specimens of these elusive ichneumonids are obtained. Townes (1962, p. 256-269) considers all North American repre- sentatives of this group as subspecies of T. planosae. In view of their allopatry and marked differences, however, I prefer to regard them as species, pending proof of intergradation. The Texas specimen was swept from a thorny bush (probably Celtis pallida) in a dry area of the Botanical Garden dominated by Prosopis julzjlora with Condalia obovata and Celtis pallida in the shrub stratum.
The above described female is the third known specimen of meso- rufus and the first from the United States. Otherwise, this species inhabits Mexico whence it is recorded by Cushman (1930, p. 2) from Cuernavaca in Morelos state and by Townes (1962, p. 259) from "40 km. southwest of Puebla" in Puebla state. 5. Joppidiurn brochum Townes
SPECIMENS EXAMINED: 1 female, Botanical Garden, 5 1 '76. HABITAT: Herbaceous undergrowth on shady side of fence row with Celtis pallida, C. lindheirneri, Ehretia anacua and other trees. DISTRIBUTION: Ky., N.C., Ga., to Okla. and Tex. and into Mkx- ico at least as far as Veracruz and Mexico City. PHAENOLOGY: Valley record for January; otherwise flies mostly in May and June.




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36 Psyche [March
6. , Joppidium rubriceps Cresson
SPECIMENS EXAMINED: 1 female, Botanical Garden, 1 IV '75. HABITAT: Herbs, grasses, and pink-flowered verbenas in bright sun.
DISTRIBUTION: N. J. to south Texas.
PHAENOLOGY: Flies from mid March to early November, appear- ing first and disappearing latest in southern part of its range. 7. Lanugo picta Townes
SPECIMENS EXAMINED: 13 females, 24 males: BOTANICAL GAR- DEN (Net: 4 females, 8 males, 1-1 5 1 '75; 4 females, 8 males, 16-26 I '75; 1 female, 4 IV '75; 1 female, 1 male, 20-31 XI1 '73; 1 female, 5 males, 24-30 XI1 '74; Malaise: 1 female, I11 '74; 1 female, 2 males, XI1 '74).
HABITAT: Open and semi-shaded areas; old fields, hedge rows, woods edges; tall grass at edge of thicket dominated by Celtis lindheimeri and C. pallida; a few specimens in Celtis thicket. DISTRIBUTION: South Texas to northern Arizona and as far south in Mexico as Chiapas.
PHAENOLOGY: Invernal, Valley records include 3 females and 8 males for December, 8 females and 16 males for January, 1 fe- male for March and 1 female for April. Flies all summer in moun- tainous parts of west Texas, Arizona and Mexico. Varies in abundance from year to year: 3 specimens in '73-'74, 34 in '74-'75, none in '75-'76 or so far in '76-'77. 8. Compsocryptus texensis Townes
SPECIMENS EXAMINED: 26 females, 6 males: BENTSEN PARK (Net: 1 male, 12-20 111 '77; 2 females, 29-30 XI1 '76); BOTANICAL GAR- DEN (Net: 6 females, 5-26 I '75; 2 females, 3 males, 28-30 111 '75; 5 females, 1 male, 2-5 IV '75; 1 male, 16-30 V '74; 1 female, 19 XI1 '76; 8 females, 20-28 XI1 '74; 2 females, 28-30 XI1 '73). HABITAT: Open, dry areas; fields, hedge rows; short grass and low herbs of incipient secondary succession; herbage of poorly tended orange groves; lawns.
DISTRIBUTION: Ka. to Okla. and Tex. south into N. Leon and Tamaulipas of Mexico.




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19771 Porter - Mesostenines 37
PHAENOLOGY: Flies from Deceirfber to May with pfak between December and April (1 3 females in Decehber, ,6'Mide'd iii".J<nuary, 2 females and 4 males in March, 5 females and 1 'rn'kle in ~pril, and 1 male in May).
s '
Varies in abundance from yeif to year: 3 specimens in "73-'74, 25 in '74-75, none in '75-'76, and 4 so far in '76-'77. ....
Genus Cryptanura . , .,
The Valley has three Cryptanura, of which'one is new and one is here recorded for the first time from the united States. V) i-
KEY TO THE U. s. CRYPTANURA
'
(Females only) r";
e, *
1. Second gastric tergite mostly mat; clypeus moreor less strongly convex in profile; humeral margin of pronotum not conically produced anteriorly, but often with a carinate elevation above end of epomia; sublateral white stripe of propodeum strongly .............................
narrowed basad of crista .2
Second tergite polished; clypeus nasute; humeral margin of pro- notum anteriorly with a prominent subconical to conical ex- pansion; sublateral white stripe of propodeum not narrowed ......................................
basad of crista .4
2. Epomia not reaching humeral margin of pronotum, the humeral margin not carinate or tuberculate anteriorly; second gastric tergite with a medio-basal white spot .................... ....................... C. septentrionalis Cushman Epomia forms a carinate elevation on humeral margin of pro- notum anteriorly; second tergite at most narrowly tinged with whitish medio-basally ................................ .3 3. Hind coxa white with conspicuous black markings; femora yel- lowish white with a broad, percurrent dorsal black band; lower metapleuron with coarse oblique wrinkling that be- comes irregular only on about dorsal 114 and with at most obscure intercalated punctures; propodeal dorsum behind basal trans-carina coarsely and irregularly wrinkled and ...........
puncto-reticulate but without discrete punctures ......................... 11. C. lamentaria (Cameron).



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38 Psyche [March
Hind coxa mostly fulvous with whitish above; femora uniformly pale fulvous; lower nietapleuron coarsely and densely punc- tate to puncto-reticulate with numerous discrete punctures dorso-anteriad; propodeal dorsuni behind basal trans-carina with abundant, nlostly discrete coarse punctures, grading into puncto-reticulation only latero-apicad near cristae ......... ........................... C. banchformis (Megerle). 4. Many segments in apical 113 of flagellum up to 1.4 as wide as long; first flagellomere 5.1 as long as deep at apex; nialar space 0.88 as long as basal width of mandible; frontal horns on a high common base; niesoscutum with abundant large punctures but with no wrinkling along notauli, except api- cad, or on outer margins of lateral lobes; mesoscutum with a large, subcircular median white spot ................... .......................... 9. C. compacta (Cresson). Segments in apical 113 of flagellum averaging about as wide as long; first flagelloniere 7.9 as long as deep at apex; nialar space 0.46 as long as basal width of mandible; frontal horns on a very low coninion base, long and sharp; n~esoscutum with moderately numerous medium sized punctures that be- come sparser niesad on lobes and with extensive transverse wrinkling all along notauli and on outer margins of lateral lobes; niesoscutuni without a median white spot .......... .................................... 10. C. vallis n. sp. 9. Cryptanura compacta (Cresson)
SPECIMENS EXAMINED: 1 female, Bentsen Park, 14 111 '77. HABITAT: Clearing with Serjania vines and tall grass on bank of Rio Grande in Salix nigra-Celtis lindheimeri woods. DISTRIBUTION: Southern Texas to Honduras. PHAENOLOGY: Townes (1962, p. 429-'30) records a female of compacta from "Cameron County, Texas, 3 August 1928". 10. Cryptanura vallis n. sp.
(Fig. 8)
Holotype: female, USA (Texas: Hidalgo County, Bentsen Rio Grande Valley State Park, 27 XI1 '76, C. C. Porter). (Townes).