Revision of Aleyroctonus Masner &amp; Huggert (Hymenoptera, Platygastridae, Sceliotrachelinae)

Zachary Lahey; Lubomír Masner; Norman F. Johnson; Andrew Polaszek

doi:10.3897/jhr.73.38383

Abstract

The genus Aleyroctonus Masner & Huggert is revised. Aleyroctonus pilatus Masner & Huggert is redescribed, and two species are described as new: A. miasmus Lahey & Polaszek, sp. nov. (Australia) and A. stanslyi Lahey & Polaszek, sp. nov. (Australia). We consider Aleyroctonus to be most closely related to a complex of three morphologically similar genera: Aphanomerus Perkins, Austromerus Masner & Huggert, and Helava Masner & Huggert. Aleyroctonus is diagnosed from other genera of Sceliotrachelinae and a key is provided to the platygastrid genera of the Aphanomerus-cluster.

Keywords

Aleuroctarthrus, Aleurodicus, Aleurodicinae, Platygastroidea, taxonomy, whitefly

Introduction

Masner and Huggert (1989) erected the genus Aleyroctonus Masner & Huggert for the type species A. pilatus Masner & Huggert, a parasitoid of Aleuroctarthrus destructor (Mackie) (Hemiptera, Aleyrodidae, Aleurodicinae) in Indonesia. Masner and Huggert (1989) included Aleyroctonus in the ‘Amitus-cluster’, composed of Amitus Haldeman, Alfredella Masner & Huggert, and Nanomerus Masner & Huggert based on its compact antennal clava, opisthognathous mouthparts, and ‘stocky’ habitus. Morphologically, however, Aleyroctonus more closely resembles Aphanomerus Perkins than it does Amitus. The densely setose axillar area (Figures 28, 32), tubular submarginal vein that is distant from the fore wing margin (Figure 46), lack of foamy structures on the propodeum and metasoma (Figures 28, 31, 38), and structure of the meso- and metasoma ally the two genera (Figures 3, 35, 41). For this reason, we transfer Aleyroctonus to the Aphanomerus-cluster of genera sensu Masner and Huggert (1989).

This research is part of an ongoing effort to revise the genera of Sceliotrachelinae, with priority given to the monotypic genera described by Masner and Huggert (1989). The purpose is to update the generic concept of Aleyroctonus, describe new species of this economically important genus, and provide an identification key to the genera of the Aphanomerus-cluster.

Materials and methods

The numbers prefixed with “NHMUK”, “OSUC”, and “USNMENT” are unique identifiers for the individual specimens (note the blank space after some acronyms). Details of the data associated with these specimens may be accessed at the following link: http://hol.osu.edu and entering the identifier in the form.

Abbreviations and morphological terms used in the text: sensillar formula of clavomeres: distribution of large papillary sensilla on the ventral clavomeres of the female (Yang et al. 2016), with the segment interval specified followed by the number of papillary sensilla (PS) per segment (e.g., A10–A8/1-2-2) (Bin 1981); LOL: lateral ocellar line, shortest distance between outer margins of the lateral and median ocellus (Masner 1980); OD: ocellar diameter, greatest width of ocellus; OOL: ocular ocellar line, shortest distance between inner orbit and outer margin of posterior ocellus (Masner 1980); POL: posterior ocellar line, shortest distance between inner margins of lateral ocelli (Masner 1980); T1, T2, ... T6: metasomal tergite 1, 2, ... 6; S1, S2, … S6: metasomal sternite 1, 2, … 6. Morphological terminology follows Masner and Huggert (1989), Mikó et al. (2007), and Lahey et al. (2019), except for that of the male genitalia which follows Johnson (1984). Morphological terms were matched to concepts in the Hymenoptera Anatomy Ontology (Yoder et al. 2010) using the text analyzer function. A table of morphological terms and URI links is provided in Suppl. material 1: Table S1.

Photographs of card- or point-mounted insects were captured with a Z16 Leica lens, JVC KY-F75U digital camera, and Cartograph software, or using a Macroscopic Solutions Macropod Micro Kit with optical slices rendered in Helicon Focus. Image stacks of card- or point-mounted insects were processed with CombineZP to produce single montage images. Photographs of slide-mounted insects were captured with a Nikon DS-Fi1 camera attached to a Nikon Eclipse 90i compound microscope with DIC illumination. Image stacks of slide-mounted insects were processed with NIS Elements BR (version 3.22.01, Build 715) to produce single montage images. The single scanning electron micrograph was produced using the methods of Talamas et al. (2016). Montage images from the various imaging systems were postprocessed for exposure and contrast with Adobe Photoshop CC.

Collections

This work is based on specimens deposited in the following repositories:

ANIC Australian National Insect Collection, Canberra, ACT, Australia

CNCI Canadian National Collection of Insects, Ottawa, Ontario, Canada

FSCA Florida State Collection of Arthropods, Gainesville, Florida, USA

NHMUK Natural History Museum, London, United Kingdom

OSUC C.A. Triplehorn Collection, The Ohio State University, Columbus, Ohio, USA

USNM Smithsonian National Museum of Natural History, Washington, DC, USA

Abbreviations and characters annotated in the figures

2Rs second abscissa of the radial sector vein (Figure 46)

apT2 anterior setal patch of T2 (Figure 3)

bcT2 basal costae of T2 (Figure 19)

bsT2 basal striae of T2 (Figure 27)

clv clava (Figures 16, 17, 25)

fs foamy structures (Figures 13, 14)

gc genal carina (Figure 36)

M median vein (Figure 46)

mfp metafemoral spines (Figure 7)

mlc median carina on mesoscutellum (Figure 18)

msc mesoscutum (Figure 8)

mssp median mesoscutellar projection (Figure 10)

ps papillary sensilla (Figure 4, 12, 25)

psu posterior mesoscutellar sulcus (Figures 11, 26)

R radial vein (submarginal vein) (Figure 46)

RS+M basal vein (Figures 1, 46)

sce setation of compound eye (Figure 20)

scu mesoscutellum (Figure 8)

tel transepisternal line (Figures 2, 6, 14)

tf transverse furrow (Figure 24)

Character discussion

Facial and malar striae

Aleyroctonus is one of the few sceliotracheline genera with facial and malar striae. Normally, the malar sulcus serves as the boundary separating the facial striae (dorsal to the malar sulcus) from the malar striae (ventral to the malar sulcus). In Aleyroctonus, the precise position of this boundary is not clear because the malar sulcus is inseparable from the facial and malar striae in terms of surface sculpture. Despite this uncertainty, we use these terms to refer to the striae on either side of where we would expect the malar sulcus to be located based on our experience with other platygastroid genera.

Metascutellar setae

Setation of the metascutellum is uncommon within Platygastroidea, occurring in several genera of Scelionidae (e.g., Bracalba Dodd, Chromoteleia Ashmead, Microthoron Masner, Oxyscelio Kieffer, Paridris Kieffer, Romilius Walker, Sceliacanthella Dodd, Tanaodytes Masner, Thoron Haliday, Thoronidea Masner & Huggert, Tiphodytes Bradley, Trichoteleia Kieffer, and Trimorus Förster) and at least one species of Metaclisis Förster (Platygastridae; USNMENT01197956). Aleyroctonus is the only sceliotracheline known to us with a setose metascutellum, a character best observed when viewed posteriorly.

Aphanomerus-cluster

The Aphanomerus-cluster was loosely defined by Masner and Huggert (1989) and includes genera with or without foamy structures on the propodeum or metasoma; with basal costae, striae, or anterolateral pits on T2; different numbers of clavomeres; and an articulated, subcompact, or compact antennal clava. We retain use of this cluster until relationships among these genera are better understood, knowing full well that the genera included in this cluster may not form a monophyletic group.

Key to genera of the Aphanomerus-cluster

1	T1 fused with T2 and S1 fused with S2, without sutures (Figures 22, 23); frons with transverse furrow above torulus (Figure 24); eyes strongly diverging ventrally (Figure 24)	Parabaeus Kieffer
–	T1 and T2 and S1and S2 separated by distinct sutures, sometimes obscured by dense setation (Figure 3); frons without transverse furrow above torulus (Figure 7); eyes not strongly diverging ventrally	2
2	Anterior margin of T2 costate or striate medially, without lateral pits (Figures 1, 19, 26, 27)	3
–	Anterior margin of T2 smooth medially, usually with 2 pits laterally (Figures 3, 8, 28)	7
3	Female antenna 7- or 8-merous; clava without sutures (Figure 12)	4
–	Female antenna 9- or 10-merous; clava with sutures (Figures 16, 17)	5
4	Female antenna 7-merous (Figure 25); clava with 3 papillary sensilla (Figure 25); posterior mesoscutellar sulcus complete (Figure 26); posteromedial surface of mesoscutellum flat	Pseudaphanomerus Szelényi
–	Female antenna 8-merous; clava with 4 papillary sensilla (Figure 12); posterior mesoscutellar sulcus incomplete medially (Figure 11); posteromedial surface of mesoscutellum with projection (Figure 10)	Calomerella Masner & Huggert
5	Claval formula 1-2-2-1; eyes distinctly setose (Figure 20); mesoscutellum with longitudinal median carina (Figure 18); transepisternal line not extending to anterior and posterior margins of mesopleuron	Indomerella Buhl
–	Claval formula 1-2-2-2; eyes glabrous or without distinct setation; mesoscutellum without longitudinal median carina; transepisternal line complete (Figure 2)	6
6	RS+M of fore and hind wings nebulous (Figure 1)	Aphanomerella Dodd
–	RS+M of fore and hind wings absent or spectral	Tetrabaeus Kieffer
7	Foamy structures on posterior surface of metapleuron present (Figures 6, 14)	8
–	Foamy structures on posterior surface of metapleuron absent (Figures 9, 36, 42)	9
8	Clava composed of articulated segments (Figure 7); ventral surface of metafemur with one or two rows of erect, stout setae (Figure 7); transepisternal line wide and straight, not reaching anterior margin of mesopleuron (Figure 6)	Austromerus Masner & Huggert
–	Clava compact, segments not articulated (Figures 16, 17); ventral surface of metafemur without rows of erect, stout setae; transepisternal line absent or thin, length variable (Figure 14)	Helava Masner & Huggert
9	Malar and facial striae present (Figures 29, 37, 43, 44); distal margin of clypeus pointed (Figures 29, 37, 43)	Aleyroctonus Masner & Huggert
–	Malar and facial striae absent (Figure 7); distal margin of clypeus truncate, not pointed (Figures 4, 5)	10
10	Mesoscutellum approximately as long as mesoscutum (Figure 8); transepisternal line absent (Figure 9)	Calixomeria Lahey & Masner
–	Mesoscutellum clearly shorter than mesoscutum (Figure 13); transepisternal line present	Aphanomerus Perkins

Key to species of Aleyroctonus

1	Genal carina present (Figure 36); antennal clava approximately as long or longer than A3–A7 (Figure 33); notauli of uniform width throughout, not strongly converging posteriorly (Figures 32, 35)	A. pilatus Masner & Huggert
–	Genal carina absent; antennal clava distinctly shorter than A3–A7 (Figure 45); notauli dilated or strongly converging posteriorly (Figures 28, 41)	2
2	Notauli strongly converging posteriorly, of uniform width throughout (Figures 28, 31); posterior mesoscutellar sulcus complete (Figure 28); length of POL greater than 2 OD (Figure 28); metasoma xanthic (Figures 28, 29)	A. miasmus Lahey & Polaszek, sp. nov.
–	Notauli not strongly converging posteriorly, dilated posteriorly (Figure 41); posterior mesoscutellar sulcus incomplete medially (Figure 41); length of POL less than or equal to 2 OD (Figure 41); metasoma black (Figures 41, 42)	A. stanslyi Lahey & Polaszek, sp. nov.

Taxonomy

Aleyroctonus Masner & Huggert

http://zoobank.org/012252F4-956E-4A7E-ADBE-955697F0F236

Aleyroctonus Masner & Huggert, 1989: 36 (original description. Type: Aleyroctonus pilatus. Masner & Huggert, by monotypy and original designation); Vlug 1995: 10 (cataloged, catalog of world species).

Description

Head . Color of head: black. Shape of head in dorsal view: transverse. Occipital carina: present. Setation of compound eye: present. Hyperoccipital carina: absent. Occipital pit: absent. Preocellar depressions: present. Position of lateral ocellus: less than 1 OD from inner margin of compound eye. Antennal scrobe: present. Sculpture of antennal scrobe: transversely striate. Sculpture of upper frons: densely reticulate. Sculpture of vertex: densely reticulate. Malar striae: present. Malar sulcus: not apparent, undifferentiated from facial and malar striae. Facial striae: present. Epistomal sulcus: absent. Central keel: present. Shape of clypeus: almost V-shaped, projecting over mandibles. Anteclypeus: undifferentiated from postclypeus. Orientation of mandiblar teeth: transverse. Mandibular dentition: bidentate. Number of maxillary palpomeres: 1. Number of labial palpomeres: 1. Number of antennomeres, female: 10. Number of antennomeres, male: 9. Number of clavomeres: 3. Sensillar formula of clavomeres: 1-2-2. Condition of A7: not fused with A8, separated by a deep suture.

Mesosoma . Epomial carina: present. Pronotal shoulders: lateral portion visible in dorsal view, not angled. Sculpture of mesoscutum: reticulate. Anterior admedian line: present as pits. Median mesoscutal line: absent. Notaulus: percurrent. Parapsidial line: present. Mesoscutal humeral sulcus: present as a thin groove. Netrion: present. Scutoscutellar sulcus: present as a deep, noncrenulate groove. Sculpture of mesoscutellum: reticulate. Shape of mesoscutellum: nearly hexagonal, widest anteriorly. Setation of axillula: dense. Metascutellum: obscured medially by posterior margin of mesoscutellum. Setation of metascutellum: present. Transepisternal line: present, terminating in anterior and posterior pits. Mesopleural carina: absent. Metapleural carina: present. Metapleural sulcus: present posteriorly. Paracoxal sulcus: absent. Number of mesofurcal pits: 3. Setation of plical area: dense. Color of legs: yellow. Protibial spur: bifid. Tibial spur formula: 1-2-2. Tarsal formula: 5-5-5. Length of tarsal claws: equal.

Metasoma . Foamy structures: absent. Number of visible terga in female: 6. Number of visible terga in male: 8. Setation of laterotergites: present. Number of visible sterna: at least 6. Sculpture of terga: absent. Laterotergites: present. Laterosternites: absent. Nucha: present, visible in dorsal view. Sculpture of nucha: costate. Shape of T1: transverse. Anterolateral pits on T2: present. Longest tergite: T2. Transverse felt field on anterior S2: present, sparsely setose. Ovipositor: Ceratobaeus-type (Austin and Field 1997).

Wings . Color of wings: hyaline. Wing development: macropterous. Length of fore wing: exceeding apex of metasoma. Marginal cilia of fore wing: present. Length of fore wing R: 1/3 length of fore wing. R of fore wing: tubular, remote from costal margin. Shape of knob of R: truncate. Cu of fore wing: spectral. M+Cu of fore wing: spectral. Marginal cilia of hind wing: present, longest along ventral margin. R of hind wing: present, 1/8 length of hind wing.

Male genitalia . Length of basal ring: 2/3 length of aedeago-volsellar shaft.

Diagnosis

The presence of facial and malar striae, a distally pointed clypeus, 3-merous antennal clava, compound eyes with long setae, setation of the metascutellum, and the absence of foamy structures on the propodeum and metasoma separates Aleyroctonus from other members of Sceliotrachelinae. Excluding the clava, these characters are also present in males of the genus, facilitating the identification of specimens of either sex.

Link to distribution map

[https://hol.osu.edu/map-large.html?id=7857]

Figures 1, 2.

Aphanomerella sp., female (USNMENT00916678) 1 head, mesosoma, metasoma, dorsal view 2 head, mesosoma, metasoma, lateral view. Scale bars: in millimeters.

Figures 3–5.

Aphanomerus spp. 3 female (USNMENT01109890), head, mesosoma, metasoma, dorsal view 4 female (USNMENT00916681), head, anterior view 5 female (USNMENT00916681), head, lateral view. Scale bars: in millimeters.

Figures 6, 7.

Austromerus grandis Masner & Huggert, female (USNMENT00916679) 6 head, mesosoma, metasoma, lateral view 7 head, mesosoma, metasoma, ventrolateral view. Scale bars: in millimeters.

Figures 8, 9.

Calixomeria lasallei Lahey & Masner, female (USNMENT01197947) 8 head, mesosoma, metasoma, dorsal view 9 head, mesosoma, metasoma, lateral view. Scale bars: in millimeters.

Figures 10–12.

Calomerella scutellata Masner & Huggert, female (USNMENT00916680) 10 head, mesosoma, metasoma, lateral view 11 mesosoma, dorsal view 12 antenna, ventral view. Scale bars: in millimeters.

Figures 13–17.

Helava spp. 13 Helava samanthae Masner & Talamas, male paratype (USNMENT00989200), head, mesosoma, metasoma, dorsal view 14 Helava samanthae Masner & Talamas, female holotype (USNMENT00989199), head, mesosoma, metasoma, lateral view 15 Helava microptera Masner & Talamas, female holotype (USNMENT00989197), head, mesosoma, metasoma, dorsal view 16 Helava samanthae Masner & Talamas, female holotype (USNMENT00989199), antenna, lateral view 17 Helava allomera Masner & Talamas, female holotype (USNMENT00989217), antenna, lateral view. Scale bars: in millimeters.

Figures 18–21.

Indomerella vanachterbergi Buhl, female holotype (RMNH.INS1104989) 18 head, mesosoma, metasoma, dorsal view 19 head, mesosoma, metasoma, lateral view 20 head, anterodorsal view 21 specimen labels.

Figures 22–24.

Parabaeus spp. 22 Parabaeus sp., female (USNMENT01197847), head, mesosoma, T1+T2, dorsal view 23 Parabaeus sp., female (OSUC 526295), head, mesosoma, metasoma, dorsal view 24 Parabaeus sp., female (USNMENT01059128), head, mesosoma, ventral view. Scale bars: in millimeters.

Figures 25, 26.

Pseudaphanomerus hyalinatus Szelényi, female (FSCA 00090462) 25 head, anterior view 26 head, mesosoma, metasoma, dorsal view. Scale bars: in millimeters.

Figure 27.

Tetrabaeus americanus (Brues), female (USNMENT01109486) 27 head, mesosoma, metasoma, dorsal view. Scale bars: in millimeters.