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Three new species of Retusigaster Dangerfield,
Austin & Whitfield, 1999 (Hymenoptera, Braconidae,
Cardiochilinae) with an illustrated key
to the New World species

Ilgoo Kang!

| Department of Entomology, Louisiana State University Agricultural Center, 404 Life Sciences Building,
Baton Rouge, LA, 70803 USA

Corresponding author: Ilgoo Kang (ikang1@lsu.edu)

Academic editor: Kees van Achterberg | Received 14 January 2022 | Accepted 4 March 2022 | Published 4 April 2022
http://zoobank. org/5D61CD92-C4DA-46F7-A048-ECA22E663F33

Citation: Kang | (2022) Three new species of Retusigaster Dangerfield, Austin & Whitfield, 1999 (Hymenoptera,
Braconidae, Cardiochilinae) with an illustrated key to the New World species. ZooKeys 1092: 47-62. https://doi.
org/10.3897/zookeys.1092.80560

Abstract

Retusigaster Dangerfield, Austin & Whitfield, 1999 is a genus of the subfamily Cardiochilinae Ashmead,
1900 and exhibits high species richness in the New World. Eight species of the genus were recorded before
this work: five species from the Nearctic region, two species from the Neotropical region, and one species
from the Palearctic region. In this article, three new species of New World Retusigaster are described based
on morphological characters: R. pulawskii sp. nov.; R. purshi sp. nov.; R. vanduzeei sp. nov. In addition,
potential food sources of the members of R. arugosus (Mao, 1949) and R. purshi sp. nov. are reported,
and an illustrated key to the New World species of Retusigaster is provided. The number of species of
Retusigaster in the New World is increased from seven to ten.

Keywords

Gossypium sp., parasitoid wasps, Purshia mexicana, taxonomy

Copyright Ilgoo Kang. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which
permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

48 Ilgoo Kang / ZooKeys 1092: 47-62 (2022)

Introduction

Retusigaster Dangerfield, Austin & Whitfield, 1999 is a genus of Cardiochilinae Ash-
mead, 1900 (Ashmead 1900) with eight valid species (Yu et al. 2016). Seven species
were recorded from the New World: R. arugosus (Mao, 1949), R. albopilosus Mercado,
2003, R. brevitarsus (Mao, 1949), R. dignus (Mao, 1949), R. noguerai Mercado, 2003,
R. pullus (Mao, 1949) and R. rubidus (Mao, 1949). One species, R. eremita (Koku-
jev, 1904) was recorded from the Palearctic region. Genus-level phylogenetic analyses,
based on morphological data, were conducted by Dangerfield et al. (1999) and Mer-
cado and Wharton (2003) and validated the genus. In the phylogeny of Dangerfield et
al. (1999), which included representatives of all the cardiochiline genera in the world,
Retusigaster was resolved as a monophyletic group. In the phylogeny of Mercado and
Wharton (2003), Retusigaster species groups, which were defined by the authors based
on the degree of thickening of the apex of hind tibia were clustered with the members
of Toxoneuron Say, 1836 (Say 1836) but made Toxoneuron paraphyletic. Regarding the
result of their analysis, Mercado and Wharton (2003) described that “Nevertheless,
Retusigaster, as defined by its type species rubidus, is readily identifiable and is accepted
here as a monophyletic group regardless of the rank eventually accorded.” In the current
project, I follow the definition of Dangerfield et al. (1999) and describe three new spe-
cies collected in the New World. Potential food sources of R. arugosus and R. purshi sp.
nov. are reported, and an illustrated key to the New World species is included. In addi-
tion, the species groups defined by Mercado and Wharton (2003) with their diagnostic
characters are re-evaluated and discussed, and the placement of R. eremita is discussed.

Materials and methods

Specimen information

The specimens for this work were borrowed from the California Academy of Sciences
(CAS; San Francisco, CA, USA), Hymenoptera Institute (HIC; Redlands, California,
USA), Museum of Comparative Zoology (MCZ; Cambridge, Massachusetts, USA),
and Texas A&M University Insect Collection (TAMU; College Station, Texas, USA).
Types of the new species will be deposited in CAS and the National Museum of Natu-
ral History (NMNH; the Smithsonian Institution, Washington D.C., USA).

Morphological analyses

Specimens were examined using a Leica MZ75 stereomicroscope. The morphological ter-
minology follows Dangerfield et al. (1999) and Sharkey and Wharton (1997). The terms
used in this work can be found as synonyms on the website of Hymenoptera Anatomy and
Consortium (2022). Terms for surface sculpture are based on Harris (1979). The following
acronyms are used for morphological terms: POL: distance between posterior ocelli, T2:

Retusigaster from the New World 49

second metasomal tergum, and T3: third metasomal tergum. Using a Visionary Digital BK
Plus imaging system (Dun, Inc.) with a Canon EOS 5DS DSLR, images were captured.
Image stacking was performed via Zerene Stacker v.1.04 (Zerene Systems LLC.). Images
were edited using Adobe Photoshop CS 6 and Photoshop CC 2022 v. 23.0 (Adobe Systems,
Inc), and final image plates were produced using the same Adobe software. Body parts were
measured using the same Adobe software mentioned. Numbers in parentheses in species
descriptions indicate 0.01x the actual size of each body character. The unit of length is mm.

Results

Taxonomy
Retusigaster Dangerfield, Austin & Whitfield, 1999

Type species. Cardiochiles rubidus Mao, 1949

Diagnosis. Dangerfield et al. (1999) and Mercado and Wharton (2003) provided
detailed diagnostic characters. Retusigaster can be easily distinguished from other car-
diochiline genera by the combination of the following characters: eye seemingly bare
(Figs 2C, 3C, 5C); clypeal tubercle absent (Figs 2C, 3C, 5C); mouthparts short (Figs 2C,
3C, 5C); scutellum apically with carinate margin (Key image 2); hind tibia without api-
cal cuplike projection (Figs 2A, 3A, 5A); ovipositor and ovipositor sheath short (Figs 2A,
3A, 5A); hypopygium entirely sclerotized and ventro-apically blunt (Figs 2A, 3A, 5A).

Distribution. Nearctic region (Canada, USA, Mexico), Neotropical region (Ja-
maica and Mexico), Palearctic region (Kazakhstan, Mongolia, Turkey, Turkmenistan).

Biology. Potential food sources of two species of Retusigaster are found. A mem-
ber of R. arugosus was collected on cotton (Gossypium sp.; Malvaceae) in Texas, and a
specimen of R. purshi sp. nov. was collected on Mexican cliffrose (Purshia mexicana (D.

Don) S. L. Welsh; Rosaceae) in Nevada.

Key to species of Retusigaster of the New World

1 IVictasoniasm@stivcOr ertitel yaale muktaaa emen sR lt hs cote, lle le 2
— IVICtASO Ma NOSTLYFOU CLINE VOCAL KY, nun thes eases Puneet ese enact eat lveedeneate eos 5

50

Ilgoo Kang / ZooKeys 1092: 47-62 (2022)

Mesosetinuniiemastlysor en bite lyplal ee Bsus Pserssdh epcnesPe al aes Mace eea assets Sul
IVicsOSCUtUITiEM OSthy-Orentitelye Carlen enna Necessssrodasstugnrecicaestepranamnernneneee

¥ ae . a vi i
y < a ¥ dj
if 5 a > 2 ~~ -*
OM te: “s “ ht ~ \ » =*
jal A : % \ Lb , = - a ss - - 4 -" «
eee ee ~ TRY ' _ Stl yr eAi vio 1 Seataess

Notauli smooth ............ccccccccccsscccsccccsccescccascccsscccsccssecesscsssseseedee Ovevitarsus
Notauli crenulate ..............cccccssecasccccsccccscccescccseccesccsesscessscsssssesscsaede rubidus

Roreiwingapicallyanfisca tel is, vn snasavenesnnenwelenrnavsasneulnsyarvane 1LATUCOSUS
Poreawing entirely intuscatees. iit. 5.q2.:cesa reas ae eta. deste DULLES

Foreny ae apical yinbuscareive mers net di eee eant ame eet peer e ema
Ore awit Oren tite iy eTnMUSCAte arhitt a tsct ac ern aot re atah earns Anse aetad Eadtass Lt

Retusigaster from the New World 51

SEO Macc muibely [yale sor oa oct sll saue wR ad ss ee URES aN Ste ee R. dignus
Stiomatentivel yr; cares Shrek od oe. Mich AO Bee AG Boe) TE aed Z

i = os “ Lh A 4 4+ — ——— 23
Rorewibiaventitelyedatktc1, ces Jars | BURN gon ey Ween R. purshi sp. nov.

Metatemmr’ entirely pale arse: cise. i058 aa ante R. pulawskii sp. nov.
Metatempren tite ty saat ke titer. cum i 8 auree, yerome Det ais suneue Roost, fhe R. albopilosus

Roremibiatentirely blacks... eis... 882 Reseda tel con ont R. vanduzeei sp. nov.
Hore tibiarentine lyapa losess.c e955. 255 cs Reso Seok ec eR Sd we ee Sea eas R. noguerai

52 Ilgoo Kang / ZooKeys 1092: 47-62 (2022)

Species descriptions

Retusigaster albopilosus Mercado, 2003

Material examined. Paratypes Mexico * 2 9; Xmatkuil, Mérida, Yucatan; 25-
28.v.1996; Wharton & Ledn; Malaise Trap. Deposited in TAMU.

Diagnosis. Members of Retusigaster albopilosus can be recognized by the combina-
tion of the following characters: body 3.5—5.5 mm; fore wing entirely infuscate with
dark stigma; fore tibia pale; mid and hind femur entirely dark; T2 entirely dark.

Description. See Mercado and Wharton (2003).

Male. See Mercado and Wharton (2003).

Biology. Unknown.

Distribution. Neotropical region (Mexico).

Retusigaster arugosus (Mao, 1949)

Material examined. Non-type specimens USA: 192; Lexington, Massachusetts;
8.ix.1963; H. E. Evans. Deposited in MCZ. 19; only collected location was labelled
(Chicago). Deposited in MCZ. 19; only collected month was labelled (July). Identi-
fied as Cardiochiles abdominalis Cresson by a previous examiner. Deposited in MCZ.
1Q; near Rio Frio, Garner State Park, Uvalde Co.; 21.vii.1986; 1400’; Wooley & Zol-
nerowich. Deposited in TAMU. 19; Brazos County, Texas; 25.vi.1937; J. E. Gillaspy.
Deposited in TAMU.

Diagnosis. Retusigaster arugosus is nearly identical to R. pullus. The members of
both species possess dark head and metasoma with pale metasoma. As Mao (1949)
mentioned, R. arugosus is distinguished from R. pullus by having basally hyaline and
apically infuscate wings (Key image 4A). Body - 5.5 mm.

Description. See Mao (1949).

Male. Unknown.

Biology (potential food source). Cotton (Gossypium sp.; Malvaceae; recorded on
the label of one specimen collected in Brazos County, Texas).

Distribution. Nearctic region (Canada, USA).

Retusigaster brevitarsis (Mao, 1949)

Material examined. Non-type specimens USA: 192; Saugus, Los Angeles, California;
18.viii.1917; J. Bequaers. Deposited in MCZ. 192; Warren, San Diego, California;
13.viii.1917; J. Bequaers. Deposited in MCZ.

Diagnosis. Members of Retusigaster brevitarsis are most similar to R. rubidus.

Retusigaster brevitarsis can be distinguished from other members of the genus by
the following characters: body length (~ 7.0mm); notauli smooth (Key image 3A);

Retusigaster from the New World 53

mesoscutum mostly orange pale; forewing entirely infuscate with dark (Key image 5B);
metasoma mostly orange pale.

Description. See Mao (1949).

Male. Unknown.

Biology. Unknown.

Distribution. Nearctic region (USA).

Retusigaster dignus (Mao, 1949)
Riggs

Material examined. Non-type specimen USA: 19; Pearsall, Texas. 30.ix.1936. De-
posited in TAMU.

Diagnosis. Retusigaster dignus can be distinguished from other members of
Retusigaster by having longer body length (- 7.5mm); fore wing apically infuscate with
pale stigma (Key Image 5A); basal spur on hind tibia 0.67 x longer than length of
basitarsus; [1 pale; T2 mostly pale, medially and submedially dark (Fig. 1).

Description. See Mao (1949).

Male. Unknown.

Biology. Unknown.

Distribution. Nearctic region (USA).

R a
han!
(ae laa iia
-— baie. } ;
ue tees. Li LZ,
e =~ ;

Se OO niet SSR 7

* e Sa
x a * = A
“ “ge - ern {eee : sit Bes 3 Oe, pervs
=

‘ s
& ae RE

Figure |. Dorsal habitus of Retusigaster dignus.

Retusigaster noguerai Mercado, 2003

Material examined. Paratype Mexico: 19; Estacion de Biologia Chamela, Jalisco, Mex-
ico; 3—9.vii.1993; Wharton & Sharkey. Non-type specimen Mexico * 19; same as previ-
ous except for collecting date and collector. 8.vii.1994; I. Mercado. Deposited in TAMU.

Diagnosis. Retusigaster noguerai is similar to R. vanduzeei sp. nov. R. noguerai can
be distinguished from other members of the genus by the combination of the following

54 Ilgoo Kang / ZooKeys 1092: 47-62 (2022)

characters: body 4.5—6.0 mm; fore wing entirely infuscate with dark stigma; fore femur
and tarsus pale; metasoma mostly dark; T2 1.0—1.3 x longer than its posterior width.
Description. See Mercado and Wharton (2003).
Male. See Mercado and Wharton (2003).
Host. Unknown.
Distribution. Neotropical region (Mexico).

Retusigaster pulawskii Kang, sp. nov.
http://zoobank.org/B6B59B 1C-GEFE-4793-BA8B-0D5DB4A67502
Fig. 2A—G

Material examined. Holotype Jamaica: 9; Port Henderson, Catherine Parish;
16.xi.1986; W. J. Pulawski. Holotype will be deposited in CAS.

Diagnosis. Retusigaster pulawskii sp. nov. is most similar to R. albopilosus. The
following characters can distinguish the new species from other species of Retusigaster:
precoxal sulcus not reaching posterior margin of mesopleuron (Fig. 2G); fore tibia en-
tirely pale (Fig. 2A); fore wing apically infuscate (Fig. 2E); transverse carina of propo-
deum reaching lateral margin (Figs 2D, 2F); stigma entirely dark (Fig. 2E); hind femur
entirely pale (Fig. 2A); metasoma mostly dark (Fig. 2B); T1 laterally orange (Fig. 2D);
Y-shaped suture of Tlentirely smooth (Fig. 2D); T2 medially orange (Fig. 2D).

Description. Body ~ 4.69 mm. Head: Antenna 37-segmented. Face width ~
1.28 x longer than its height (73:57). Interantennal space with median carina.
Width of anterior ocellus ~ 0.92 x longer than POL (11:12). Eye seemingly with-
out interommatidial setae; median width of eye ~ 0.97 x longer than the median
width of gena in lateral view (31:32). Gena extended ventroposteriorly into weak
prominence. Clypeus ~ 2.25 x longer than its height (54:24); clypeal tubercles ab-
sent. Mandible bidentate. Maxillary palpus five-segmented. Labial palpus four-seg-
mented. Galea short. Glossa short. Occipital carina absent. Mesosoma: Notauli en-
tirely crenulate, strongly crenulate posteriorly. Scutellar sulcus ~ 0.44 x longer than
width (19:43), with three carinae. Postscutellar depression finely crenulate. Prono-
tum dorsally crenulate and posteriorly rugulose. Mesopleulon mostly smooth, pos-
terior margin strongly crenulate; precoxal sulcus crenulate not reaching posterior
margin; epicnemial carina absent; episternal scrobe present. Metapleuron anterior-
ly smooth and posteriorly rugulose. Propodeum strongly rugulose, ~ 0.36 x longer
than its median width (36:100); propodeal areola heart-shaped, ~ 1.17 x longer
than its maximum width (27:23); transverse carina reaching lateral margin. Legs:
Basal spur on fore tibia ~ 0.58 x longer than length of basitarsus (19:33). Basal
spur on mid tibia ~ 0.63 x longer than length of basitarsus (30:48). Hind tibia
without apical cup-like projection; basal spur on hind tibia ~ 0.64 x longer than
length of basitarsus (47:74); claws pectinate. Wings: Fore wing ~ 4.14 mm; second
submarginal cell trapezoid, ~ 3.20 x longer than height (80:25); 1r absent; 3r ab-
sent; RS evenly curved; pterostigma ~ 2.89 x longer than wide medially (81:28).

Retusigaster from the New World 55

Hind wing ~ 3.43 mm; 2r-m absent; 2—1A basally present. Metasoma: T1 ~ 1.32
x longer than its posterior width (66:50), anteriorly with lateral carina; Y-shaped
suture of Tlentirely smooth. T2 ~ 0.34 x longer than its posterior width (36:105),
~ 0.95 x longer than T3 (36:38). T3 ~ 0.36 x longer than its posterior width
(38:106). Hypopygium without median longitudinal fold. Protruded ovipositor
sheath ~ 0.27 x longer than length of hind basitarsus (20:74), apically with short
setae. Color: Body mostly dark brown. Fore wing apically infuscate; stigma entirely
dark. The following areas orange: fore tibia; all femora, basal mid and hind tibiae;
medial and lateral T1; medial T2.

Etymology. Named in honor of Dr Wojciech Jerzy Pulawski, Curator of Entomol-
ogy, Emeritus, at CAS, the person who collected the specimen from Jamaica.

Biology. Unknown.

Distribution. Retusigaster pulawskii sp. nov. is known from a single female speci-
men collected in Jamaica.

Figure 2. Retusigaster pulawskii sp. nov. A lateral habitus B dorsal habitus C anterior head D dorsal

propodeum to T3 E wings F dorsal mesosoma G mesopleuron and metapleuron.

Retusigaster pullus (Mao, 1949)

Material examined. Non-type specimens USA ¢ 19; three miles east of Presidio, Tex-
as; 1-3.v.1963; H. E. Evans. Deposited in MCZ. 19; Randall County, Texas; Bush-
land; 26.vii.-7.viii.1983; T. J. Kring; Malaise trap. Deposited in TAMU.

Diagnosis. By having dark head and mesosoma with pale metasoma, members of
R. pullus and R. arugosus can be distinguished from the other members of Retusigaster.
The members of R. pullus are distinguished from the members of R. arugosus by having
entirely infuscate wings (Key image 4B).

Description. See Mao (1949).

Male. Unknown.

Biology. Unknown.

Distribution. Nearctic region (USA).

56 Ilgoo Kang / ZooKeys 1092: 47-62 (2022)

Retusigaster purshi Kang, sp. nov.
http://zoobank.org/F46EE693-08F0-45 D5-ABEF-0E30F533153B
Fig. 3A-E

Material examined. Holotype USA: 2; 36°16.15'N, 115°33.29'W; Telephone Can-
yon, Clark County, Nevada, USA; 16.vi.1998; K. Keen & M. Andres; Collected on
Purshia Mexicana. Holotype will be deposited in NMNH.

Diagnosis. Retusigaster purshi sp. nov. is most similar to R. vanduzeei sp. nov.
The following characters can distinguish R. purshi sp. nov. from other species of
Retusigaster: body ~ 7.0 mm, mostly black except for medial mandible (reddish
brown) and ovipositor (Fig. 3A, C); precoxal sulcus crenulate reaching posterior
margin (Fig. 3A); propodeal areola pentagonal (Fig. 3B); fore wing apically infus-
cate with dark stigma (Fig. 3A); fore tibia entirely dark; Y-shaped suture posteri-
orly crenulate (Fig. 3B).

Description. Body ~ 7.06 mm. Head: Head entirely with long setae. Antenna
44-segmented. Face width ~ 1.56 x longer than its height (128:82). Width of anterior
ocellus ~ 0.70 x longer than POL (16:23). Eye seemingly without interommatidial
setae; median width of eye about ~ 0.90 x longer than the median width of gena in
lateral view (47:52). Gena extended ventro-posteriorly into moderate prominence. Cl-
ypeus ~ 2.46 x longer than its height (96:39), with punctures; clypeal tubercles absent.
Mandible bidentate. Maxillary palpus five-segmented. Labial palpus four-segmented.
Galea short. Glossa short. Occipital carina absent. Mesosoma: Notauli entirely evenly
crenulate. Scutellar sulcus ~ 0.45 x longer than width (28:62), with seven carinae,
posteriorly rugulose. Postscutellar depression dorsally rugulose and ventrally crenu-
late. Pronotum dorsally crenulate and posteriorly rugulose. Mesopleuron dorsally with
punctures and ventrally crenulate and rugulose, posterior margin strongly crenulate;
precoxal sulcus crenulate reaching posterior margin; epicnemial carina absent; epister-
nal scrobe present. Metapleuron anteriorly smooth and posteriorly rugulose. Propo-
deum strongly rugulose, ~ 0.38 x longer than its median width (61:162); propodeal
areola pentagonal, ~ 1.45 x longer than its maximum width (48:33); transverse carina
reaching lateral margin. Legs: Basal spur on mid tibia ~ 0.64 x longer than length of
basitarsus (40:63). Hind tibia without apical cup-like projection; basal spur on hind
tibia ~ 0.61 x longer than length of basitarsus (57:93); claws pectinate. Wings: Fore
wing ~ 6.59 mm; second submarginal cell trapezoid, ~ 3.02 x longer than height
(124:41); 1r present as basal stump; 3r absent; RS evenly curved; pterostigma about
3.00 x longer than wide medially (105:35). Hind wing ~ 4.57 mm; 2r-m absent;
2—1A present reaching basal half. Metasoma: T1 ~ 1.01 x longer than its posterior
width (93:92), anteriorly with lateral carina; Y-shaped suture of T1 anteriorly smooth
and posteriorly crenulate. T2 ~ 0.27 x longer than its posterior width (43:158), ~
0.77 x longer than T3 (43:56). T3 ~ 0.34 x longer than its posterior width (56:164).
Hypopygium without median longitudinal fold. Protruded ovipositor sheath ~ 0.29
x longer than length of hind basitarsus (27:93), apically with long setae. Color: Body

Retusigaster from the New World 57

mostly black. Wings basally hyaline and apically infuscate. Pterostigma entirely dark
brown. Mandible apically black. Apical tarsomeres pale.

Etymology. Named in honor of Fredrick Traugott Pursh, a German American
botanist. The genus of the potential food source was also named after him, Purshia.

Biology (potential food source). Mexican Cliffrose (Purshia mexicana (D. Don)
S. L. Welsh; Rosaceae)

Distribution. Retusigaster purshi sp. nov. is known from one female specimen col-

lected in Telephone Canyon, Clark County, Nevada, USA. (Fig. 4)

USA NV Clark Co
Telephone Canyon, 8,
36°16.15°N 115°33 ~
.29°W 16 Jun 1998
16 June 1998,
_K.Keen, M.Andres
Cowanisa

mexicana

Figure 3. Retusigaster purshi sp. nov. A lateral habitus B dorsal habitus C anterior head D dorsal meso-

soma E forewing.

58 Ilgoo Kang / ZooKeys 1092: 47-62 (2022)

ere eo 4 Sy A i tS Ts est r - > Fe 1 be rie 4 7

Figure 4. Habitat near the type locality of Retusigaster purshi sp. nov. in Nevada, USA.

Retusigaster rubidus (Mao, 1949)

Material examined. Non-type specimens Mexico * 32; seven miles east of San Luis
Potosi; 3.vii.1987; 6225’; R. Wharton. USA ¢ 19; same as previous except for collect-
ing date and collector. 8.vii.1994; I. Mercado. Deposited in TAMU.

Diagnosis. Members of Retusigaster rubidus are most similar to those of R.
brevitarsis. R. rubidus can be distinguished from other members by the following
characters: body ~ 7.5 mm. notauli crenulate (Key image 3B); mesoscutum mostly
orange pale; fore wing with pale stigma (Key image 6A); metasoma mostly orange pale.

Description. See Mercado and Wharton (2003).

Male. Unknown.

Host. Unknown.

Distribution. Nearctic region (USA and Mexico).

Retusigaster vanduzeei Kang, sp. nov.
http://zoobank.org/6CF56EA2-C9D0-4CEA-B780-17D6D6613E66
Fig. 5A—H

Material examined. Holotype USA ® 2; Nixon, Washoe County, Nevada; 30.vi.1927;
EP Van Duzee. Holotype will be deposited in CAS.

Diagnosis. Retusigaster vanduzeei sp. nov. is most similar to R. noguerai Mercado.
Using the following characters, the members of R. vanduzeei sp. nov. can be distin-
guished from other members the genus: inner and outer orbits orange (Fig. 5A—E); fore

Retusigaster from the New World 59

CA ei
Figure 5. Retusigaster vanduzeei sp. nov. A lateral habitus B dorsal habitus C anterior head D dorsal head
E lateral head F wings G mesopleuron and metapleuron H scutellum to T3.

wing entirely infuscate (Fig. 5F); precoxal sulcus crenulate nearly reaching posterior
margin (Fig. 5G); propodeal areola oval (Fig. 5H); metasoma entirely dark (Fig. 5B);
T1 antero-laterally crenulate and postero-laterally slightly rugulose; T2 ~ 0.27 x longer
than its posterior width (Fig. 5B, H).

Description. Body ~ 6.32 mm. Head: Head entirely with long setae. Antenna
37-segmented. Face width ~ 1.50 x longer than its height (96:64). Width of ante-
rior ocellus ~ 0.80 x longer than POL (16:20). Eyes seemingly without interom-
matidial setae; median width of eye about ~ 1.15 x longer than the median width
of gena in lateral view (45:39). Gena extended ventro-posteriorly into moderate
prominence. Clypeus ~ 2.67 x longer than its height (72:27), with punctures;
clypeal tubercles absent. Mandible bidentate. Maxillary palpus five-segmented.
Labial palpus four-segmented. Galea short. Glossa short. Occipital carina absent.
Mesosoma: Notauli entirely evenly crenulate. Scutellar sulcus ~ 0.30 x longer than
width (22:74), with six carinae; lateral margins forming cup-like pit posteriorly.
Postscutellar depression entirely rugulose. Pronotum mostly rugulose. Mesopleu-
ron dorsally and ventrally with punctures, posterior margin strongly crenulate;

60 Ilgoo Kang / ZooKeys 1092: 47-62 (2022)

precoxal sulcus crenulate nearly reaching posterior margin; epicnemial carina ab-
sent; episternal scrobe present. Metapleuron anteriorly smooth and posteriorly
rugulose. Propodeum strongly rugulose, ~ 0.40 x longer than its median width
(57:142); propodeal areola nearly oval, ~ 1.31 x longer than its maximum width
(42:32); transverse carina absent. Legs: Basal spur on fore tibia ~ 0.58 x longer than
length of basitarsus (29:50). Basal spur on mid tibia ~ 0.64 x longer than length
of basitarsus (39:61). Hind tibia without apical cup-like projection; basal spur
on hind tibia ~ 0.61 x longer than length of basitarsus (55:90); claws pectinate.
Wings: Fore wing ~ 6.06 mm; second submarginal cell trapezoid, ~ 3.06 x longer
than height (110:36); 1r absent; 3r absent; RS evenly curved; pterostigma about ~
3.34 x longer than wide medially (117:35). Hind wing ~ 4.88 mm; 2r-m absent;
2—1A present reaching basal half. Metasoma: T1 ~ 1.13 x longer than its posterior
width (79:70), antero-laterally crenulate and postero-laterally slightly rugulose. T2
~ 0.27 x longer than its posterior width (37:136), ~ 0.55 x longer than T3 (37:67).
Hypopygium without median longitudinal fold. Protruded ovipositor sheath ~
0.46 x longer than length of hind basitarsus (41:90), apically setaceous. Color:
Body mostly black. Wings entirely infuscate. Pterostigma entirely dark brown.
Antenna dark brown. Inner and outer orbits orange. Mandible medially reddish
brown. First laterotergite brown.

Etymology. Named in honor of Mr Edward P. Van Duzee, a former curator of
CAS and fellow of Entomological Society of America (ESA), the person who collected
the specimen.

Host. Unknown.

Distribution. Retusigaster vanduzeei sp. nov. is known from Nixon, Washoe

County, Nevada, USA.

Discussion

Mercado and Wharton (2003) separated the two species groups, R. arugosus and
R. rubidus, by the degree of expansion of the apex of hind tibia and the shape and
location of the propodeal spiracles as mentioned in the introduction section. I
examined and compared the diagnostic characters of all the species of Retusigaster
designated by Mercado and Wharton (2003). In my examination, I did not see a
distinct difference in the hind tibial character between the two groups. The shape
of the propodeal spiracles (Fig. 6) was somewhat useful to identify the species
groups rather than the location of the propodeal spiracle, but still it was not easy
to confidently distinguish two species groups based on the shape. Accordingly, the
new species are placed neither in R. arugosus nor in R. rubidus due to the difficulties
separating the two species groups based on the suggested diagnostic characters by
Mercado and Wharton (2003). Further research based on molecular data will clarify
the relationships among species and species groups of Retusigaster and Toxoneuron.

Retusigaster from the New World 61

Figure 6. A propodeal spiracle of R. arugosus B propodeal spiracle of R. vanduzeei sp. nov.

Regarding the placement of R. eremita, Mercado and Wharton (2003) were unsure
of the placement because the species is only a member of Retusigaster recorded from
the Palearctic region. I was also inquisitive about its generic placement and reviewed
the species descriptions by Telenga (1955) and Tobias (1995) to reconfirm the place-
ment of the species. Telenga (1955) wrote that the members of R. eremita possess much
thickened tips of hind tibiae and simple claws, which have not been recorded in other
species of Retusigaster. Both of the characters suggest placement in Pseudcardiochilus
Hedwig, 1957 among the Old World cardiochilines. According to the description by
Tobias (1995), the members of R. eremita have simple claws but the apices of their
hind tibia are not as expanded as those of Pseudcardiochilus acutus (Tobias & Alexeey,
1977). However, because I did not examine type specimens of R. eremita, I do not
change the generic placement of the species. Erdogan (2015) reported the first record
of R. eremita from Turkey, but the species may not be R. eremita because of its ex-
tremely different body coloration.

Acknowledgments

I am grateful to Mr Chris Grinter at CAS, Ms Crystal Maier and Mr Charles Far-
num at MCZ, and Dr Karen Wright at TAMU for specimen loan. I would like to
thank Dr Michael Sharkey for reviewing the manuscript and Dr van Achterberg for
sharing his documents about Pseudcardiochilus. Among the people at LSU, I would
like to acknowledge Drs Chris Carlton, Michael Stout, and Rodrigo Diaz for help
and support, and Ms Victoria Bayless for her encouragement. Finally, I am grateful
to the LSU Agricultural Center and LSU Entomology Department for financial and
logistical support.

62 Ilgoo Kang / ZooKeys 1092: 47-62 (2022)

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