Rungaspis neotropicalis Wei, Schneider, Normark & Normark, 2021

Wei, Jiufeng, Schneider, Scott A., Normark, Roxanna D. & Normark, Benjamin B., 2021, Four new species of Aspidiotini (Hemiptera, Diaspididae, Aspidiotinae) from Panama, with a key to Panamanian species, ZooKeys 1047, pp. 1-25 : 1

Rungaspis neotropicalis Wei, Schneider, Normark & Normark sp. nov.

Figures 4 , 5

Material examined.

Holotype: Panama • 1 adult female; Parque Nacional San Lorenzo Canopy Crane , Colón; 9.2802°N, 79.9754°W; 20.vi.2012; GE Morse & BB Normark leg.; on Marila laxiflora Rusby; MIUP (D4168I) . Paratypes: • 4 adult females; same data as holotype; USNM (D3953K, D4168B, D6550C, D6552B) ; • 5 adult females; same data as holotype; UMEC (D3953J, D3953P, D3995B, D4168E, D6703C) .

Description.

Adult female (N = 10) in some cases pupillarial, enclosed within sclerotized cuticle of 2nd instar; some individuals non-pupillarial. Appearance in life not recorded. Slide-mounted adult female 350-610 μm long (holotype 540 μm, median 540 μm), 280-500 μm wide (holotype 410 μm, median 420 μm), broadest at mesothorax. Body outline broadly oval, with slight indentation between prothorax and mesothorax. Derm membranous throughout at maturity in pupllarial individuals; cephalothorax and pygidium becoming sclerotized at maturity in some non-pupillarial individuals. Antennae simple, each with one long seta. Distance between antennae 51-73 μm. Eye a submarginal dorsal tubercle on prothorax. Without disc pores associated with anterior or posterior spiracles. Venter of mesothorax with about 6 transverse, irregular rows of sclerotized spicules in submedial area, posterolaterad of mouthparts. Lobes. Pygidium with 1 or 2 pairs of lobes; L1 well developed, subquadrate, with parallel inner margins separated by exceedingly narrow space, lobes slightly longer than wide, rounded apically, with 1 large notch near apex on lateral margin and 0-1 notch near apex on medial margin; L1 each with well-developed basal sclerosis, slightly narrower and longer than lobe; L2, when fully developed, forming a small, sclerotized projection, about one-third length of L1 and much narrower, without notches; L2 often absent or represented by a membranous projection or low, sclerotized point; L3 absent. Plates. With 2 narrow, elongate plates in first space, slightly fringed, with a few tines, and 1 or 2 simple plates laterad of position of L2; no other plates present. Ducts. Dorsal macroducts of 1-barred type, slender, much broader than ventral microducts, few in number, restricted to margin of pygidium; with 1-3 (usually 2) ducts in first space, 0-2 (usually 1) immediately laterad of L2, and 0-1 (usually 0) laterad of seta marking segment VI, making a total of only 1-4 ducts (usually 4) on each side of pygidium. Ventral microducts exceedingly narrow, present along pygidial margin and scattered in submedial areas of other segments. Paraphyses absent. Anal opening subcircular, 8-11 μm in length and width, positioned 17-37 μm from base of L1, located within posterior half of pygidium. Perivulvar pores absent.

Second-instar female (N = 8) Appearance in life not recorded. Slide-mounted second-instar female 340-620 μm long (median 460 μm), 270-400 μm wide (median 340 μm), broadest at mesothorax. Body outline oval. Antennae simple, each with one long seta. Distance between antennae 54-96 μm. Without disc pores associated with anterior or posterior spiracles. Lobes. Pygidium with 3 pairs of well-developed lobes; L1 subquadrate, with parallel inner margins separated by exceedingly narrow space, lobes slightly longer than wide, rounded apically, with 1 large notch near apex on lateral margin and 0-1 notch near apex on medial margin; L1 each with well-developed basal sclerosis, slightly narrower and longer than lobe; L2 nearly as long as L1 but much narrower, rounded at apex, without notches or with slight notch on lateral margin; L3 subtriangular, slightly narrower and shorter than L2, without notches. Plates. Without plates between L1. With 2 narrow plates in first space, 2 broader plates in second space, and a series of 5 or 6 plates laterad of L3. All plates similar in length to adjacent lobes and fringed at apex, with plates anterior to L3 becoming progressively lower and less fringed anteriorly. Plates of the first and second spaces subtended by conspicuous ducts, about a third as wide as dorsal macroducts and nearly as long, much wider and longer than ventral microducts. Ducts. Dorsal macroducts of 1-barred type, broad, all submarginal; with 2 ducts in a short row arising from first space, 2 in the second space, and 1 laterad of L3, making a total of 5 on each side of pygidium. Ventral microducts exceedingly narrow, short, present along pygidial margin and scattered in submedial areas of other segments. Paraphyses absent. Anal opening oval to subcircular, 8-14 μm in length, 7-8 μm in width, positioned 23-40 μm from base of L1, located within posterior half of pygidium.

DNA sequences.

Several DNA sequences of Rungaspis neotropicalis have been published, including fragments of 3 gene regions: the large ribosomal subunit (28S; D3953H, D3953J, D3953R, D3953V, D4168B, D4168E,D4168I, D4168J, D4249H, D4249L; Genbank accession numbers MT677181-MTT677184, MTT677266-MTT677296, MT677294), elongation factor 1-alpha (EF-1α; D3953J, D3953V, D3953W, D3995B; D4168A, D4168B, D4168E, D4168J, D4249H, D4249L; KY221749, MH915953, MH915954, MT64783, MT642022, MT642025-MT642029, MT642031, MT642032), and cytochrome oxidase I and II (COI-II; D3953H, D3953J, D3953R, D3953V, D3995B, D4168A, D4168B, D4168E, D4168I, D4168J, D4249G, D4249H, D4249L; KY221137, MH916549, MT676875-MT676878, MT676946-MT676950, MT676971, MT676972, MT676974).

Informal synonyms.

Specimens of R. neotropicalis have appeared in published analyses and phylogenetic trees, where they were labeled "UG3995 ud3995" ( Schneider et al. 2018; Normark et al. 2019), "UG3953 ud3953" ( Schneider et al. 2018), or " Rungaspis ud3995" ( Peterson et al. 2020).

Remarks.

This is an unusual species both in its life history, showing intraspecific variation in the pupillarial habit, and in its biogeography, having affinities to African species. Some slide-mounted specimens are unequivocally pupillarial, having well-developed 1st instars inside of adult females that are themselves inside of 2nd-instar cuticles. More often than not, these adult females are flipped inside their puparia, with their head at the posterior end of the puparium. Other specimens are apparently non-pupillarial, and some of these have a sclerotized cephalothorax, a feature not seen, to our knowledge, in adult females of any pupillarial species. We had originally intended to describe the pupillarial and non-pupillarial forms as two different species, but the three sequenced gene regions show no differences between them and there are no consistent morphological differences either; therefore, we consider them to comprise a single species that includes both pupillarial and non-pupillarial developmental phenotypes. The second instar has a more completely developed secretory system than the adult, with more ducts, plates, and lobes - a pattern typical of pupillarial species and opposite to what is typical of non-pupillarial species. This may imply that this species is derived from a pupillarial ancestor and that the non-pupillarial form represents a secondary loss of the pupillarial habit.

Molecular phylogenetic studies have shown that R. neotropicalis has affinities with African species. Probably the best analysis is a recent study of Aspidiotini ( Schneider et al. 2018), which shows R. neotropicalis nested within a clade of African Aspidiotus species ( A. fularum Balachowsky, A. elaeidis Marchal, and an undescribed species from Uganda), with R. neotropicalis sister to A. fularum . R. neotropicalis was also included in a broader study of Diaspididae ( Normark et al. 2019), where it appears in a clade that consists mostly of African species ( A. elaeidis , Selenaspidus kamerunicus Lindinger, S. articulatus Morgan, Dynaspidiotus rhodesiensis (Hall), and Entaspidiotus lounsburyi (Marlatt)) but that also includes one other New World species ( Rugaspidiotus arizonicus (Cockerell)). It is possible that R. neotropicalis is an African species that is invasive in the Neotropics, similar to Selenaspidus articulatus , which is the single most abundant diaspidid species at the site where R. neotropicalis was collected ( Peterson et al. 2020). But if this species is from Africa, it does not seem to have ever been found there. Based on the available evidence we regard it as a native Neotropical species, perhaps one resulting from an ancient trans-Atlantic dispersal event.

We tentatively place this species in the genus Rungaspis Balachowsky. Rungaspis presently comprises four species distributed in Africa and the southwestern Palearctic. Rungaspis neotropicalis resembles the other species of Rungaspis in having large basal scleroses of L1, reduced L2 and L3, cephalothoracic sclerotization at maturity (in non-pupillarial specimens), dorsal ducts with sclerotized orifices, and simplified plates located only in the first and second interlobular spaces. African Rungaspis species differ from R. neotropicalis in having conical plates without fringes (vs. slightly fringed) and numerous narrow dorsal ducts (vs. few broad ducts). We considered three other possible placements for the species. One was the genus Aspidiotus Bouché. Rungaspis neotropicalis resembles Aspidiotus species in having basal scleroses of L1 and fringed plates, and molecular evidence indicates that its closest known relative is an African species of Aspidiotus . But we concluded that R. neotropicalis shares a greater number of characters with Rungaspis . Furthermore, Aspidiotus is radically non-monophyletic, and the mostly African clade to which R. neotropicalis belongs should probably be recognized as a distinct genus anyway ( Schneider et al. 2018). Another possible placement we considered was the genus Helaspis McKenzie. Helaspis is a New World genus that "appears to suggest Aspidiotus more strongly than any known genus" ( McKenzie 1963). With R. neotropicalis it shares basal scleroses of L1 and a sclerotized cephalothorax. But Helaspis has other extraordinary features - conical plates and bilobed L3 - that seem to indicate an affinity with the tribe Gymnaspidini rather than Aspidiotini ( Normark et al. 2019). Rungaspis neotropicalis lacks these characters and is clearly a member of Aspidiotini . We also considered erecting a new genus for R. neotropicalis - this is the course taken by many diaspidid systematists faced with such an unusual species - but we concluded that that was not appropriate in this case given the evidence for affinity with Rungaspis .

Morphologically, R. neotropicalis also closely resembles Aspidiotus rhusae (Brain), a pupillarial species known from South Africa. The two species share a similar overall body shape, L1 with basal scleroses, absence of L3, absence of perivulvar pores, and presence of just a few slightly fringed plates and just a few broad, one-barred dorsal ducts near the pygidial margin. Characters that distinguish R. neotropicalis from A. rhusae are as follows (character of A. rhusae given in parentheses): L2 much narrower than L1 or absent (L2 nearly as broad as L1); space between L1 exceedingly narrow, without plates (space between L1 with pair of apically fringed plates); 4 or fewer dorsal ducts present on each side of pygidium (5 or more ducts present); 1-3 microducts present near each posterior spiracle (cluster of 5 or more ducts in this position); transverse rows of minute spicules present on mesothorax posterolaterad of mouthparts (absent); body margin slightly indented between prothorax and mesothorax (entire); eye a submarginal dorsal tubercle (eye marginal). The Neotropical species that R. neotropicalis most closely resembles is Aspidiella rigida Ferris. The two species both have L1 with basal scleroses and closely approximated medial margins, other lobes reduced or absent, cephalothorax becoming sclerotized at full maturity, and perivulvar pores absent. Characters that distinguish Rungaspis neotropicalis from Aspidiella rigida are as follows (character of A. rigida given in parentheses): plates present (absent); dorsal ducts of pygidium broad, much broader than ventral microducts, confined to margin and submargin (narrow, similar to ventral microducts, widely scattered); anus in posterior half of pygidium (anterior half).

Our study of Neotropical and African species that resemble Rungaspis neotropicalis has further led us to conclude that Aspidiella rigida belongs in the genus Rungaspis , and we transfer it accordingly: Rungaspis rigida (Ferris) comb. nov. Ferris (1941) remarked, "It is with much doubt that this species is here referred to the genus Aspidiella . In its pygidial characters it resembles the type genus closely enough except for the entire absence of plates and the absence of the perivulvar pores... In the heavy sclerotization of the entire body it is peculiar and distinctive." In each of these characters it resembles Rungaspis species more than Aspidiella species. Ferris further expressed puzzlement that an Oriental and Australian genus such as Aspidiella would include a species that was apparently native to the Neotropics. A biogeographic connection between the Neotropics and Afrotropics is better documented (by Rungaspis neotropicalis and in groups such as Diaspis Bouché) and less of a surprise.

Host plant.

Marila laxiflora Rusby (family Calophyllaceae )

Etymology.

The specific epithet is a Latin adjective; here it alludes to this species’ unusual biogeography as a Neotropical member of a mostly African clade.

Distribution.

Panama ( Colón).

Figures

Figure 4. Rungaspis neotropicalis Wei, Schneider, Normark & Normark sp. nov. Adult female, full body view, illustrated from the holotype (D 4168 I); expanded view of pygidium, illustrated from the holotype (D 4168 I).

Figure 5. Rungaspis neotropicalis Wei, Schneider, Normark & Normark sp. nov. Second-instar female, full body view.