Melaleucaphylus, Schwartz & Weirauch & Schuh, 2018

Schwartz, Michael D., Weirauch, Christiane & Schuh, Randall T., 2018, New Genera And Species Of Myrtaceae-Feeding Phylinae From Australia, And The Description Of A New Species Of Restiophylus (Insecta: Heteroptera: Miridae) Michael D. Schwartz Christiane Weirauch, Bulletin of the American Museum of Natural History 2018 (424), pp. 1-161 : 26-29

Melaleucaphylus , new genus

TYPE SPECIES: Melaleucaphylus sheathianae , new species.

DIAGNOSIS: Similar in general appearance to Moissonia spp. in ovoid, somewhat flattened body form; but distinguished from members of that genus by endosoma with distal portion of ventral strap usually bifurcate with flat rounded or truncate anterior apex situated adjacent to proximal edge of secondary gonopore and diverse posterior apex terminating in variablelength pointed spur, small variably curved subapical spine, or long hollow spine; dorsal strap usually bifurcate with narrow elongate spine(s); secondary gonopore usually with distinctive distally narrow proximal sclerite; sometimes distal end of secondary gonopore with large, serrate, mostly membranous lobe produced on left side. Overall appearance and occasionally fleshy parempodia also similar to species of Melaleucoides Schuh and Weirauch (Semiini, Exocarpocorina) , but distinguished from members of that group by subtribal level differences in structure of endosoma and left paramere.

DESCRIPTION: MALE: Macropterous, total length 2.74–4.30, pronotum width 0.97–1.57. COLORATION (pls. 1–4): Variable; ranging from pale or dirty yellow to black, lighter specimens usually with small darker regions on various portions of head, pronotum, hemelytron, and appendages; sometimes dorsum with overall orange red cast, or with relatively discrete portions of bright orange red on mesoscutum, scutellum medially, and cuneus. SURFACE AND VESTITURE (figs. 5B, 6B, 7B, 8B, 10B, 11B, 12B, 14A, pls. 1–4): Dorsal vestiture variable, sometimes with uniformly distributed yellow, golden, or black setae; often a mixture of pale and dark setae covering similarly colored portions of dorsum; dorsum rarely with silvery sericeous setae; ventral vestiture usually longer than on dorsum; coxae sometimes with erect black setae. STRUC-

TURE: Head: Barely projecting; interocular space ranging from 1.5–2× as wide as dorsal width of an eye; eyes leaving gena narrowly exposed in lateral view (figs. 5A, 6A, 7A, 8A, 10A, 11A, 12A). Antenna: Segment 2 weakly tapering, more slender at base; length ranging from subequal to head width to approximately one-quarter longer; ventral margin of eye reaching ventrad of antennal fossa by width of fossa. Labium: Length variable, reaching from apex of meso- to metacoxa. Thorax: Pronotum: Subquadrate, lateral margins nearly straight, calli weakly demarcated, posterior lobe flat, posterior margin straight; mesoscutum broadly exposed; metathoracic spiracle and scent-gland system typically phyline (figs. 5C, 6C, 7C, 10C, 11C, 12C). Pretarsus: Claws of variable size, curvature, and basal thickness; parempodia variable— straight or curved setiform with apices pointed, clipped, or lamelliform, gradually widening, truncate or rounded; pulvilli of variable size and conformation on ventral surface of claw (figs. 4, 9, 13, 14B). Hemelytron: Sublinear, gently curved at base and apex. GENITALIA (figs. 5D, 6D, 7D, 11D, 12D, pls. 8A–K, 9, 10, 11A–J, 12A–K, 13, 14A–J, 15A–J, 16, 17A–J, 18A–J, 19, 20A–J, 21A– I, 22A–J, 23A–J, 24A–J, 25A–L): Pygophore: Moderate to large in size, broadly conical, with slight prominence on each side subbasally on dorsal surface; caudal surface usually not extending perpendicular to genital aperture in lateral view; paramere insertions without tubercles, sometimes with obscure patches of bristles. Endosoma: Sigmoid, composed of dorsal and ventral straps, portion with torsion and extent twisting left or caudal variable; sometimes straps divergent in middle and separated by membrane. Ventral strap: Emanating from dorsal side of endosomal base, distal portion entire or bifurcate at variable distance from apex; if strap entire, then anterior surface dominant with length and apical conformation variable; usually posterior surface or edge with subapical spine of variable length and conformation protruding beyond curvature of ventral strap; sometimes subapical spine a large hollow elongate prong; if strap bifurcate, posterior surface or edge with variablelength spur, not protruding beyond curvature of ventral strap. Dorsal strap: Emanating from ven- tral side of endosomal base, entire or bifurcate with variable length and orientation, apically pointed. Sometimes dorsal strap notched, or ventral strap offset at level of proximal edge of secondary gonopore. Secondary gonopore: Well sclerotized, located medially or just distad of middle of endosoma, aperture open on ventroanterior surface; almost always with prominent proximal process of various size and conformation, usually adhered to proximal margin of secondary gonopore, projecting distad, terminating with variable apex; distal edge of secondary gonopore with microspiculate membranous patch of variable size on lateral surface; sometimes membranous sac emanating from proximal edge of secondary gonopore; sometimes interstrap membrane with very thin sclerite reaching from secondary gonopore to base of endosoma. Phallotheca: Large, variously attenuate apical region with undulate margins and posterior and anterior crest shaped flanges on dorsal aspect, sometimes posterior surface with small spine; aperture on anteroventral surface, long, narrow more broadly open at apex; right anterior margin gently curved—without long narrow spine. Long strut on right margin internally and a curved strongly sclerotized plate on posterior surface; sometimes ventroposterior surface of apical region with outpocket. Parameres: Left paramere: Posterior margin and shoulder region between posterior and anterior processes at most slightly elongate, sometimes with small short protuberance, otherwise typically phyline; posterior process with moderate length, gently attenuate, straight or slightly bent ventrad distally, apex small, rounded, base at most slightly expanded. Right paramere: Subrectangular, moderately elongate, usually with short distal region and small rounded apex; sometimes distal region and apex slightly longer.

FEMALE: Coloration and structure similar to male, except costal margin slightly more convex, frons more produced anteriorly, antennal segment 2 more slender and strongly tapering proximally than in male; total length 2.94–4.83, pronotum width 1.03–1.71. GENITALIA (pls. 8L–O, 11K– M, 12L–O, 14K–N, 15K–N, 17K–M, 18K–M, 20K–M, 21J–L, 22K–O, 23K–O, 24K–Q, 25M–Q): Posterior margin of sternite 7: Bearing elongate or broadly triangular posteriorly directed projection; sometimes broad proximally and narrow apically. Vestibular sclerites: Size variable, large to moderately large, J-shaped, coiled tube, projecting from right paramedial side of ventral labiate plate or comprising a small shieldlike medioventral extension of ventral labiate plate; in posterior view forming convoluted tube stretching continuously from proximal region of first gonapophyses to strongly microspiculate surface on posterior edge of ventral labiate plate; in dorsal view placed medially between sclerotized rings and sometimes extending to border of right sclerotized ring, to middle of, or to just beyond anterolateral ring margin. First gonapophyses: Symmetrical subtriangular or asymmetrical subrectangular sclerites abutting proximal portion of right vestibular sclerite; with pair of small elongate sclerites distal to base of vestibulum. Ventral labiate plate: Variously sclerotized portion of vestibular base; surface ventral to sclerotized rings microspiculate. Dorsal labiate plate: Relatively large, subhexagonal, transverse, wider than long, lateral margin indented and slightly infolded. Sclerotized rings: Usually large, subovoid, ovoid, or subrectangular, broadly concave, separated by one-half width or width of ring; perimeter narrow, lateral margin sometimes angled and reaching lateral margin of dorsal labiate plate. Posteroventral margin of dorsal labiate plate notched on midline, usually bilateral regions folded on narrow crease, sometimes strongly symmetrically or asymmetrically tumid. Posteromedial region: Ventral surface facing genital chamber forming pair of concave, microspiculate invaginated plates, divided on midline, sometimes medial edges overlap; posterior margins slightly tumid, curved dorsad, forming pocket under base of lateral oviducts and spermathecal gland; sometimes plates strongly sclerotized and spiculate. Anterolateral region: Broad microspiculate region anterior of rings. Intersegmental membrane: With variable invaginated process projecting anteroventrad into genital chamber; shape and size variable, usually large subtriangular, membranous with anterior margin microspiculate; sometimes apically notched or posterior margin sclerotized and combined with dorsoposterior plate of posterior wall. Posterior wall: Variably sclerotized, not divided on midline, without paramedial anterior projections; anterior surface microspiculate; usually anterior one-half strongly sclerotized, posterior portion membranous. Interramal sclerites: Widely separated, wedge shaped anteroventrad; midline variably invaginated or depressed with posterior surface abutting bulb of ovipositor; usually knoblike or broadly longitudinal. Interramal lobes: Usually dorsoposterior region with widely separated, gently rounded, and somewhat tumid lateral swellings; when anteromedial region of interramal sclerite broadly invaginated and protuberant posteriad, adjacent paramedial membranous regions somewhat narrowly protuberant.

ETYMOLOGY: Named for the occurrence of many of the known species on the genus Melaleuca ( Myrtaceae : Melaleuceae ). The known hosts for Melaleucaphylus spp. also include members of genera in the Myrtaceae tribes Chamelaucieae , Leptospermeae , and additional genera in the Melaleuceae .

DISCUSSION: Members of this taxon bear an uncanny resemblance to many species that Schuh and Weirauch (2010) placed in the genus Melaleucoides and often share the same host plants (see table 5 and Discussion, p. 96). Examination of both the male and female genitalia, however, indicates that these two genera do not belong to the same tribe within the Phylinae . Schuh and Weirauch (2010) placed considerable emphasis on the weakly fleshy structure of the parempodia in the recognition of the Melaleucoides group of genera ( Harpagophylus , Melaleucoides , Thryptomenomiris ; see following discussion in Exocarpocorina ). Scanning micrographs for species of Melaleucaphylus indicate that fleshy parempodia are more widespread and with a greater diversity of form than previously recognized (see figs. 4, 9, 13, 14B).

The diagnosis of this genus is based primarily on the unique features of the endosoma. In particular, we point to the presence of a prominently thick, twisted proximal extension or process of the secondary gonopore, a variable projection emanating from the ventral strap located apically or subapically on the posterior surface, and the usually bifurcated apical spine of the dorsal strap. The female genitalia do not have the array of diverse paramedial structures projecting anteriad into the genital chamber from the mostly membranous, medially divided posterior wall as documented by Schuh and Weirauch (2010) for multiple species of Melaleucoides (Semiini, Exocarpocorina) . In contrast, Melaleucaphylus spp. have a medially undivided, well-sclerotized posterior wall with an obvious pair of lateral subquadrate interramal sclerites on the anterior portion: one, a variably sclerotized invagination of the medial portion that projects posteriad and abuts the base of the ovipositor and the other a medial invagination or process of the intersegmental membrane situated between the posterior margin of the dorsal labiate plate and the posterodorsal margin of the posterior wall that projects ventrad into the genital chamber. The ventral surface of the intersegmental invagination is usually microspiculate and variably notched apically. In those species where the vestibulum is appreciably developed the vestibular sclerites are either arranged medially or slightly bent to the right. The sclerotized rings of Melaleucaphylus are consistently large, thin walled, and usually subovoid. The dorsal labiate plate in some species of Melaleucaphylus has a pair of thin, tumid, membranous lobes on the posterior edge, a feature of the female genitalia not previously documented in phylines.

The endosoma in Melaleucaphylus can be organized into several groups. Some of the species united by endosomal structure also share features of the female genitalia. Almost all the species in which the posterior surface of the ventral strap has a small subapical spine also have— to a varying degree—a paired billowy membrane on the posterior edge of the dorsal labiate plate, a longitudinal deep invagination of the medial portion of the posterior wall, flat intersegmental process with an entire apical margin, and an angulate lateral edge of the sclerotized rings.

HOST-PLANT ASSOCIATIONS: Of the Melaleucaphylus spp. with known hosts, there is strong evidence that all these plants belong to three tribes of Myrtaceae (subfamily Myrtoideae ); only 2% of Melaleucaphylus specimens collected were not taken from myrtaceous plants (see tables 1 and 2). For M. nodosae , M. omnivorus and M. vimineae , three species with many well-documented myrtaceous host plants, non-Myrtaceae records were considered to be commingling of specimens in the field. Host associations for M. dubiosus , M. kaputar , and M. ngarkat , are unknown and will be determined only through additional field work. Melaleucaphylus spp. were found on 5 genera of Chamelaucieae (17% of host spp.), 2 genera of Leptospermeae (6% of host spp.), and 4 genera of Myrtaceae (78% of host spp.). Melaleuca and Beaufortia (Melaleuceae) are the most utilized of the 11 genera of myrtaceous hosts (74% and 12% of individual host associations respectively). Baeckea is the most utilized Chamelaucieae with 7% of the individual host associations; Calytrix , Pileanthus , Scholtzia , and Verticordia are known from singleinstance host associations. For the Leptospermeae single-instance host associations are documented for Kunzea and Leptospermum .

Of the 15 spp. of Melaleucaphylus with known hosts 83% of the individual host associations are known by a single collecting event, 12% by two collecting events, and 5% by 4 collecting events. Almost one-half of Melaleucaphylus spp. are apparently restricted to a single host-plant species ( M. eremaeae , M. glomeratae , M. halmaturorum , M. kunzeae , M. pauperiflorae , M. rhaphiophyllae , and M. viridiflorae ), 3 spp. ( M. beaufortiae , M. micranthae , M. sheathianae ) have 2 hosts, 2 spp. ( M. nodosae , M. phymatocarpi ) have 3 hosts. Three Melaleucaphylus spp. have more numerous hosts: M. omnivorus (8 spp.), M. polyphagus (6 spp.), and M. vimineae (9 spp.). Five Melaleucaphylus spp. ( M. nodosae , M. omnivorus , M. phymatocarpi , M. polyphagus , and M. vimineae ) are found on hosts of more than one Myrtaceae tribe.

GEOGRAPHICAL DISTRIBUTION: As presented in table 4, eight of the 18 Melaleucaphylus spp. are known solely from a limited region in southwestern Western Australia of high botanical endemism; two of these species are also found in desertic habitats of the Northern Territory, South Australia, and Victoria. The remaining species of Melaleucaphylus are known from New South Wales (4 spp.), Northern Territory (2 spp.), South Australia (1 sp.), and Victoria (1 sp.). The southwestern portion of Western Australia comprises all of the southwestern and southwest interzone subregions of the phytogeographical classification of Australia ( González-Orozco et al., 2014; Ebach et al., 2015) as well as the western borders of the western and eastern desert subregions. For Melaleucaphylus 58% of the species and 60% of the collection events and specimens occurred in these 4 subregions of Western Australia. The southeastern subregion in New South Wales supports the next highest number of species (12%), collection events (20%), and specimens (15%). Two species, M. polyphagus and M. vimineae are shared by more than one state and subregion; only the former is known east and west of the Nullarbor Plain with the latter occurring in southwestern Western Australia and the central desert region of Northern Territory.