Derbid Planthoppers (Hemiptera: Fulgoroidea: Derbidae) Associated with Coconut and Oil Palm in Brazil

We present surveys of derbid planthoppers associated with coconut (Cocos nucifera L.) and oil palm (Elaeis guineensis Jacq.) collected in Northeastern (Sergipe) and North (Pará and Roraima) Brazil. The surveys were intended to contribute to our knowledge of possible vectors of phytoplasmas or other phloem-restricted plant pathogens. Eight derbid taxa were found, two in the subfamily Cedusinae, tribe Cedusini (Cedusa yipara Kramer and C. yowza Kramer) and six in the subfamily Derbinae, tribe Cenchreini: Herpis sp., Persis pugnax Stål, Omolicna anastomosa (Caldwell), O. nigripennis (Caldwell), and two new species in the genus Agoo Bahder & Bartlett are described here. Genus-level features between Omolicna and Agoo are discussed and a key to the species of Agoo is provided.


Introduction
Coconut tree (Cocos nucifera L.) is the fourth most important perennial fruit tree in Brazil, with approximately 158,477 ha of cultivated area (IBGE 2018). Eighty-five percent of the plantations cover less than 10 ha and are in the hands of small farmers, the rest concerns big private agro-industrial companies (Fontes & Wanderley 2006, Martins & Jesus Júnior 2014. Over the last 20 years, coconut water has become one of the most important high value-added products of the agroindustry of Brazil (Fontes & Wanderley 2006) and the country is the world's fourth largest producer of coconuts (FAO 2020).
Given the importance of coconut in Brazil, the arrival of a serious disease such as lethal yellowing (LY) would be catastrophic (Dollet & Talamni 2018). In Jamaica, LY has caused the death of millions of coconuts and it has destroyed 90% of the coconuts of the Atlantic coast of Honduras in less than 10 years (McGrath 2002, Rocca 2013. LY was reported in more than 30 species of palms in Florida (Dollet & Talamani 2018, Sullivan & Harrison 2013, suggesting that the disease may be a broad threat to indigenous palms in Amazonian region. Valuable palms that might be threatened include the açai palm (Euterpe oleracea Mart. and E. precatoria Mart.), the buriti palm (Mauritia flexuosa L. f.), babaçu (Attalea speciosa Burret), pupunha (Bactris gasipaes Kunth), and others that are important sources of food and other products (Balick 1979, Kahn 1991, Mtiiz-Miret et al 1996, Brondizio 2011, Tunçer & Schroeder 2017.
LY is caused by phytoplasmas that are phloem-limited pathogens transmitted by insects that feed exclusively on phloem tissue (McCoy et al 1983, Eden Green 1997. Known vectors of phytoplasmas are in the order Hemiptera, suborder Auchenorrhyncha, mostly families Cixiidae and Cicadellidae (subfamily Deltocephalinae). Derbidae and Flatidae also have been suggested as possible vectors (Mpunami et al 2000, Clair et al 2001, Wilson 2005, Weintraub & Beanland 2006, Philippe et al 2007, Philippe et al 2009, Lee & Wilson 2010, Rodrigues et al 2010, Rajan 2013, Halbert et al 2014. For this reason, surveys for early detection of LY and potential vectors are being made in Brazil. Here, we report Derbidae found during surveys of coconut and oil palm (Elaeis guineensis Jacq.) in Northeastern (Sergipe) and North (Pará and Roraima) Brazil. Two of the species found are described as new species and a key to the species of Agoo Bahder & Bartlett is provided.

Material and Methods
Study areas and survey methods MPEG. Additional study specimens are deposited in Embrapa (Empresa Brasileira de Pesquisa Agropecuária) in Aracaju and Roraima, Brazil.

Morphological terminology and specimen techniques
Abdomens were cleared by soaking in 10% KOH solution overnight (or 20% hot KOH for~15 min) for examination. Morphological terminology generally follows that of Bartlett et al (2014), except forewing venation following Bourgoin et al (2015) and with male terminalia nomenclature modified after Bourgoin (1988) and Bourgoin & Huang (1990). Authorship of the two new species should be attributed to Bahder and Bartlett. Photographs and measurements were taken using a digital imagery system. Line art was digitally traced from photographs. All measurements are in millimeters (mm). Specimen measurements were taken for descriptive (not statistical) purposes and are from type material.
Label information of holotypes types is quoted, with '/' indicating new line and '//' indicating next label and with supplemental information given in brackets. For other material examined, label data were rewritten to maintain consistency in pattern, beginning with the country, state or province, and more specific locality, followed by the collection date, collector, and lastly, the number, sex of specimens, and specimen depository given in parentheses. Type material and other specimens examined at UDCC were provided with 2D barcode labels and data captured using "Arthropod Easy Data Capture" (Schuh et al 2010, Schuh 2012, Arthropod Easy Capture 2013 in the NSF sponsored "Tri-Trophic Thematic Collection Network" (Tri-Trophic TCN, http://tcn.amnh.org/). These data are available via the iDigBio (www.idigbio.org) specimen portal.

Identification and classification
Derbid specimens were identified to higher taxon following Metcalf (1938) and Fennah (1952) as updated by O'Brien (1982) and Emeljanov (1992Emeljanov ( , 1996. Species level identifications used available keys and illustrations, and in some cases by comparison with photos of primary type material. The genus Cedusa Fowler was identified using Flynn & Kramer (1983) and Kramer (1986); Omolicna Fennah by Caldwell (1944), Fennah (1945, Halbert et al (2014), andBahder et al (2019); Herpis Stål using Metcalf (1938) and O'Brien (1982, 1987; Persis Stål using Metcalf (1938) and Fennah (1945Fennah ( , 1952 (Fig 1). Coconut plantations (Cocos nucifera L., Arecaceae) were visited in those municipalities in order to identify plants with LYTS and the presence of potential insect vectors, leafhoppers, and planthoppers. Oil palm plantations (Elaeis guineensis Jacq., Arecaceae) were also visited in the south of the State for searching vectors. All plants were observed for symptoms similar to LYTS in leaves of the basal third or at least 20 plants of each plantation. Planthoppers were collected with a mouth-aspirator or caught with a tube and preserved in 70% alcohol. Derbidae were also collected on the lower leaves of coconuts in the Coconut International Bank for Latin America and the Caribbean (ICG-LAC) located in Itaporanga D'Ajuda, Sergipe State, in Northeastern Brazil. Other derbids were collected using sweeping net and mouth aspirator in a plantation (Brazilian Green Dwarf Jiqui) of Northern Pará state in Santa Izabel do Pará. Insects were collected on the lower leaves of the palms. Information about sampled plantations and geographic coordinates are provided in Table 1

Results
Eight taxa from the family Derbidae were found associated with palms in these surveys (Table 1). Of these, two were in the genus Cedusa Fowler (Cedusinae: Cedusini). This genus comprises 148 species in the New World and 32 in Africa, although the latter taxa are probably better placed in Malenia Haupt (Fennah 1961, Szwedo 2006. Species of Cedusa are often externally very similar and recognition relies almost entirely on features of male terminalia (Flynn & Kramer 1983, Kramer 1986). Cedusa has previously been suggested as a possible vector of lethal yellowing phytoplasmas in Jamaica (Brown et al 2006). However, no experimental transmission of LY was obtained in Jamaica. The remaining derbid species were all in the Derbinae, tribe Cenchreini. The extant Cenchreini consists of 22 genera and 186 species, of which 10 genera and 59 species occur in the New World (two genera, as currently defined, occur in both hemispheres) (Bourgoin 2020). These taxa consisted of Persis punax Stål, Herpis sp. and five species in or near the genus Omolicna Fennah.
Taxa found associated with coconut and oil palm in Brazil 1. Cedusa yipara Kramer, 1986. One specimen (sample SJ1c) (Fig 2A) Flynn & Kramer (1983) and Kramer (1986), which collectively treated 147 species in the genus, plus C. quixoa Kramer, subsequently moved to Cedochrusa Emeljanov (Emeljanov 2008), separated principally by features of the male genitalia. Cedusa yowza Kramer (reported below), previously reported from Panama, is (as noted by Kramer 1986) very similar to Cedusa yipara, separated from this species by the aedeagal flagellum (endosoma) terminating with semicircular process bearing a subapical fin and apical microteeth (in C. yowza, see Kramer 1986, Fig 80), versus flagellum terminating truncately (Kramer 1986, Fig 83). The C. yipara specimen from Vila Nova Colina differs in having the apical process on the left side of the aedeagus not distinctly forked and the right paramere not as narrowed. Further investigation is needed to determine the variation found in C. yipara and whether there are undescribed species of Cedusa on palms in Brazil. We have not been able to match the single obtained specimens with any of the described species, including any of the three species known from South America. This genus is poorly known from Brazil, with Herpis fuscovittata Stål, the only species previously reported Table 1 Derbidae species associated with coconut and oil palm in Brazil.

Species Host Sampled place
State/municipality/locality Geographical coordinates Number on map (Fig 1) from Brazil, and the type species of the genus. We obtained photographs of the type specimen of Herpis fuscovittata from the Swedish Museum of Natural History, Stockholm (NHRS-GULI000058748), which showed H. fuscovittata to be a much paler species. This specimen does not appear to match the descriptions of either of the other two species reported from South America (viz., H. chiriquensis (Fowler), reported from Guyana and Panama, and H. metcalfi O'Brien from Guyana (as British Guiana; Muir 1918, Metcalf 1945, O'Brien 1987. The specimen probably represents an undescribed species, but we have not definitively been able to exclude the described Mesoamerican species because of incomplete original descriptions and limited accessibility to type material. 4. Persis (Persis) pugnax Stål. One male (sample 22937) ( Fig 2C)  Amended diagnosis. The members of Agoo are pale forms, with the head in lateral view appearing smoothly rounded from posterior margin of vertex to the frontoclypeal suture. The lateral carinae of the vertex and frons are foliate such that the vertex and frons are concave. The median carina of the vertex and frons appears absent and there is no transverse carina at the fastigium. The frons narrower and paranota more strongly foliate than Omolicna. The terminalia are nearly bilaterally symmetrical; the aedeagus is stout with a strongly retrorse flagellum bearing differing, symmetrical arrangements of processes. The ventral lobe of pygofer (ventral view) broad, distally attenuating to rounded apex. Anal tube is stout, elongate, and ventrally sinuate.
Remarks. The genus Agoo (originally a subgenus of Omolicna) is most readily separated from Omolicna by the foliate carinae of the head, the profile of the head being strongly rounded, and the more strongly foliate antennal fossae compared with Omolicna. The terminalia of Agoo are nearly bilaterally symmetrical (more so than Omolicna), and the midventral lobe of the opening of the pygofer is elongately rounded, and the anal tube is ventrally sinuate (lacking convexity found in most Omolicna). Bahder et al (2019) showed a high pairwise distance between Agoo xavieri Bahder & Bartlett and five species of Omolicna, with a percent nucleotide difference range from 24.4 to 31.1% for CO1 and~10.6% for a 1493 bp region of 18S.
At present, all members of the genus Agoo are associated with palms (Arecaceae).
In the key to genera of Cenchreini presented by O'Brien (1982, modified from Fennah 1952, species of Agoo key with difficulty because of several ambiguous features (carinae of vertex pustulate; frons narrow, compressed; subantennal fovea present, subcostal cell long, Sc+R fork about level with Cu1 fork and union of claval veins, claval apex in basal half of wing). Depending on interpretation of features, Agoo might key to Cenanges Fennah, Neocenchrea Metcalf, or Phaciocephalus Stål. Cenanges and Neocenchrea can be excluded based on an examination of specific features, especially male genitalia (photos of the type specimen of Cenanges spectralis Fennah from The Natural History Museum, London were examined). Phaciocephalus appears to be paraphyletic, with 28 species, principally from the Indomalayan region and Oceania except for 3 species (doubtfully included) from Brazil. Photographs of the type specimens of the Brazilian Phaciocephalus were obtained from the Swedish Museum of Natural History, Stockholm, to compare with the new species of Agoo.
Forewing (Figs. 12A and 13A) with a row of pits along basal 1/2 of ScP+R and basal half of postcubitus. Cluster of pits between RA and ScP and two rows of four sensory pit basad of ScP. Forks of R and CuA veins at approximately the same level, both well proximad of claval apex, but near level of Pcu+1A fusion. Claval apex just near midpoint of wing, fork of M near claval apex. Branching pattern: Sc and RA unbranched, RP 2-branched, MP 4-branched and CuA 2branched plus short branch at claval apex. Fusion of Pcu+A1 in proximal third (A1 closely approximate to trailing margin of wing). Forewing length males: 5.4-5.8 mm; females: 5.5-5.9 mm.
Terminalia. Pygofer, in lateral view, widest at base, abruptly narrowed to irregularly sinuate margins, anterior concave, caudal convex (Fig 7C). In ventral view, opening of pygofer with midventral elongately rounded lobe (Fig 7B), attenuating distally to rounded apex. Gonostyli broad and cupped (in lateral view, Fig 7C), expanded distally; dorsal margin near midlength bearing a rounded projection with a laterally directed sclerotized tooth (gonostyli distally expanded, giving the appearance of a notch after this projection). Gonostyli in ventral view (Fig 7B) with medially directed projection near midlength bearing two short sclerotized spines on inner margin, distal spine about twice as large as basal spine. Apodemes of gonostyli conspicuous, extending beyond pygofer into abdomen. Phallotheca stout (Fig 6D-F), approximately bilaterally symmetrical; shaft of phallotheca with elongate retrorse processes near apex (each with irregularly arranged serrations near midlength), one each side of large retrorse flagellum; flagellum with 2 pairs of elongate apical processes (apparently articulated, about equal-sized) arranged in transverse row (Figs 6D, E); and 1 elongate midventral process. Anal tube in lateral view roughly triangular, distally broadened, ventrally sinuate, caudal margin concave at anal column, ventrocaudal portion elongate (apically rounded) ( Fig  7C). In dorsal view, anal tube notched on caudal aspect; anal column short, appearing quadrate.
Distribution. Brazil (Roraima). Diagnosis. Male pygofer with median ventral process broad near base, attenuating distally to broadly rounded apex (lateral teeth lacking); lateral margins of pygofer opening with acuminate transversely projecting processes. Gonostyli in ventral view with acuminate medially directed lobe, trailing edge of lobe irregularly tri-lobed. Flagellum of aedeagus with pair of dorsal retrorse processes arising near junction with aedeagal shaft.
Thorax. Pronotum narrow (length at midline 0.21-0.25 mm), anterior margin following contours of posterior margin of head ( Fig 9B); medially convex and truncate behind vertex, narrowed behind eyes. Posterior pronotal margin medially concave; median carina of pronotum very weak, lateral carinae distinct, reaching caudal margin; anterior keel following anterior margin of pronotum behind eye to antennal fossa in paradiscal field. In lateral view (Fig 9C), posterior margin of pronotum foliate, appearing inflected upward; lateral portion of paradiscal field forming strongly foliate fossa, enveloping posterior margin of antennae, and partially surrounding antennae both dorsally and ventrally. Mesonotum appearing slightly elevated in lateral view; in dorsal view with median and 2 lateral longitudinal carinae, reaching scutellum. Scutellum separated from scutum by inflection, dorsolateral angles of scutellum bearing lateral projections (may be hidden by forewings in repose). Mesonotum length at midline 0.68-0.77 mm, width at tegulae 0.75-0.81 mm.
Forewing (Figs 12B and 13B) with a row of pits along basal 1/2 of ScP+R (+M) and basal half of postcubitus. Venation ScP+RA forked from RP in basal 1/3 of wing. Fork of CuA and fusion of Pcu+1A at nearly same level; ScP (unbranched) from RA at about wing midlength; RP 2branched; MP 4-branched; CuA 2-branched plus short branch near apex of clavus; claval apex at nearly wing midlength; A1 tracking wing margin (wing margin inflected to be obscured in lateral view of body); combined Pcu+1A reaching margin before apex of clavus.
Terminalia. Pygofer in lateral view widest near base (Fig 11C), proximal and distal margins irregularly sinuate, subparallel; proximal margin concave, distal convex with an acuminate transversely projecting process just below midlength (Fig 10G). Pygofer opening in ventral view bearing an elongate lobe, widest at base and attenuating distally to rounded apex. Gonostyli (in lateral view) broad (Fig 11C), distally expanded into rounded, cup-like structure; apex bluntly rounded; dorsal subapical region with pair of asymmetrical lobes, each bearing a large, the distal lobe with the tooth directed medially, the proximal lobe with tooth directed laterad; in ventral view (Fig 11B), each gonostylus bearing a large, triangular lobe directed dorsomedially, their dorsal surfaces sclerotized and irregularly lobed (Fig 10H). Apodemes from gonostyli elongate and conspicuous projecting into abdomen beyond pygofer. Phallotheca stout (Fig 10D-F), nearly bilaterally symmetrical; shaft with small laterodorsal subbasal tooth on each side and elongate retrorse process arising at each side of flagellum base (these appearing partly serrulate in dorsal view); apex of shaft subtended by pair of cupped projections from ventral surface (giving appearance of apical notch in dorsal view); aedeagal flagellum strongly retrorse bearing 4 pairs of elongate processes, 1 dorsal pair near flagellar base, 1 pair on flagellar underside, arising near base and 2 apical pairs arranged in a roughly transverse row (lateral pair longer), appearing articulated at base (Fig 10D, E). Anal tube stout in lateral view broadly triangular, broadened caudally, dorsal margin straight to anal column, ventral margin sinuate, apex rounded; in dorsal view caudal margin apically concave anal column short (Fig 11C).
Etymology. The species name is from the Latin term spina meaning thorn, a reference to the process on the lateral margins of the pygofer opening. The term is intended to be feminine in gender. Remarks. Agoo spina sp. n. and Agoo argutiola sp. n. both differ from Agoo xavieri in the form of the flagellum of the phallotheca-both of the new species possess a terminal transverse row of 4 processes, whereas A. xavieri does not. Agoo spina and Agoo argutiola are quite similar except that the former possesses an acuminate medially directed lobe on the lateral margin of pygofer opening (lacking in A. argutiola) and possesses a pair of elongate retrorse processes on the dorsum of the flagellum (lacking in A. argutiola).

Discussion
In this work, we document eight species of planthoppers in the family Derbidae associated with coconut or oil palm in Brazil. Undoubtedly, there are other derbid species to be found associated with palms. Additional derbids not reported here were collected in Bonfim (East of Boa Vista), Boa Vista, Nova Colina, and Mucajai that remain to be investigated, including specimens similar to Omolicna and Cedusa. The presence and abundance of derbids on palms has been observed many times; for example, Howard (2001) lists 91 derbid species reported from palms, nearly doubling the number compiled by Lepesme (1947). Zelazny & Pacumbaba (1982) report collecting 4978 derbid specimens representing 15 taxa from coconut palms in Luzon, Philippines. Wilson et al (1994) report 36% of the derbid plant association records compiled by them are from palms, and 63% of derbid species with host associations are reported from a single plant species. Available data in FLOW (Bourgoin 2020) indicate that 16.7% of published plant associations for Derbidae are Arecaceae, more than any other plant family (next are Poaceae and Sapindeceae at 11.4% each).
The nymphal stages of derbids are associated with moist organic debris (e.g., Wilson 1987a, Wilson et al 1994 and are assumed to feed on fungal hyphae (e.g., Wilson et al 1994, Bartlett et al 2014, and adults move to plants to feed and mate. It is possible that the association between palms and derbids (at least for some derbid species) has less to do with nutrition, and more to do with relationships between palms and derbid larval habitat, or plant structure or allelochemistry as they relate to mate-finding or substrate-born communication (Wilson 1987b).
While the association between some derbids and palms is evident from current survey efforts in Costa Rica (Bahder et al 2019(Bahder et al , 2020a, the biological significance is not. Habitats where members of the genus Agoo have been sampled extensively and in great numbers have failed to identify non-palm host plants (Bahder, unpublished data). There has been no unequivocal evidence that derbids transmit palm pathogens, which remains a critical issue. Powell et al (2015) documented the presence of the 16SrIV-D phytoplasma in the newly discovered Omolicna joi; however, this was based on DNA extraction from the whole body of the insect. Detection of phytoplasma from whole-body extractions of insects has some use in vector studies because it allows for the identification of species that are in fact feeding on infected palms. However, positive reactions using this approach are highly susceptible to obtaining false positives. Screening for phytoplasmas is commonly done using the 16S gene which is highly conserved and commonly results in the amplification of other species of bacteria from the insect gut or that it has acquired through feeding (Wally et al 2008). Another form of false positive is when the whole body is tested and true phytoplasma DNA is amplified but is residual phytoplasma passing through the gut. Residual pathogens can be detected in non-vectors (Cieniewicz et al 2018) so to understand if derbids do contribute to transmission of phytoplasmas, screening of salivary glands will need to be performed on specimens to assess if they are capable of transmitting the phytoplasma in question.
That two of the species we found had not been previously described is a testament both to the incompleteness of past survey work of palm-associated planthoppers, and the taxonomic challenges associated with the derbid tribe Cenchreini. Among the Cenchreini, there has been no quantitative phylogenetic treatments at any level and the diagnostic morphological differences among genera are incompletely defined. Diagnostic molecular work to supplement species descriptions and test generic placement (e.g., to confirm placement of the new species described here in the genus Agoo) and monophyly are needed both to amend basic science (i.e., taxonomy, especially to define species, investigate intraspecific variation and confirm associations of males, females and nymphs) but also to provide additional diagnostic and applied tools.