Thaumastocoris petilus Drake and Slater, 1957

Noack, Ann E., Cassis, Gerasimos & Rose, Harley A., 2011, Systematic revision of Thaumastocoris Kirkaldy (Hemiptera: Heteroptera: Thaumastocoridae), Zootaxa 3121, pp. 1-60 : 46-48

Thaumastocoris petilus Drake and Slater, 1957

(Figures: 7C,D; 15A–G; 19C)

Thaumastocoris petilus Drake and Slater, 1957: 367 (description); Slater 1973: 154 (note); Cassis and Gross 1995: 394 (catalogue); Cassis, Schuh and Brailovsky 1999: 30 (diagnosis; distribution; host plants)

Holotype: 3, AUSTRALIA, VICTORIA, Kiata, Oct. 1928 F.E. Wilson ( USNM).

Other material examined. NORTHERN TERRITORY: 43, 4Ƥ, Palm Valley, Finke Gorge National Park, 24°3’37”S 132°44’37”E, 586 m, 11 April 2001, G Cassis, RT Schuh, MD Schwartz, R Silveira and MA Wall, locality code [CA01_L51_H241, ex Melaleuca glomerata (AM; UNSW). SOUTH AUSTRALIA: 43, 2Ƥ, 18km S of Bews, Ngarkat Conservation Park, 35°33’07”S 140°25’59”E, 60 m, 9 November 1998, RT Schuh, G Cassis and R Silveira, locality code [98-36, ex Melaleuca uncinata R. Br. ( NSW 427353) (AM; UNSW). WESTERN AUS- TRALIA: 53, 5Ƥ, Brand Highway, 8.2km N of Eneabba,. 29°44.771’S 115°15.240’E, 100 m, 31 October 1996, RT Schuh and G Cassis, locality code 96-L46-H137, ex Melaleuca rhaphiophylla Schauer (Perth05120195) (AM; UNSW); 1Ƥ, Kalamunda, 31°58’S 116°01’E, 22. April.2008, landed on human, P Murphy ( WAAD); 13, Moorine Rocks, 11.7 km N Great Eastern Highway on Noongar Road, 345m. 31°13’42”S 118°58’44”E, 4 December 1997, RT Schuh, G Cassis, H Brailovsky, A Asquith, locality code 97-L01, ex Malleostemon tuberculatus (AM); 153 15Ƥ Mosman Park, Perth, 32°01’33”S 115°45’57”E, 7 August 1999, G. Cassis, locality code L2-H8, ex Melaleuca rhaphiophylla (AM); 133, 8Ƥ, Mosman Park, Perth, 32°1.254’S; 115°46.1215’E, 20 m, 15 November 1999, RT Schuh, G Cassis and R Silveira, locality code WA99-L1-H2, ex Melaleuca rhaphiophylla (AM; UNSW); 23, 2Ƥ Ravensthorpe Range, nr river, 33°29’20”S 120°08’01”E, 25 May 2007, ex beat, ML Moir and MC Leng WAM 46 ( MMPC); 1Ƥ, Swan River, AM Lea ( WAAD); 13, 4km N of South Coast Highway on lake Magenta road, 360 m, 33°46.7034’S 119°17.3145’E, 29 November 1999, RT Schuh, G Cassis and R Silveira, locality code WA99-L47, ex Melaleuca sp. (AM); 13, 7.9km N of Ravensthorpe, 400 m, 33°32.175’S 119°59.957’E, 5 November 1996, RT Schuh and G Cassis, locality code WA96-L61-H164, ex Melaleuca cucullata Turcz. (Perth05236657) (AM); 183, 14Ƥ, 13.4 km N of Peak Charles National Park, 32°47.234’S 121°14.617’E, 275 m 20 November 1999, RT Schuh, G Cassis and R Silveira, locality code WA99-L18-H062, ex Melaleuca uncinata R. Br. (Perth05670756) (AM; UNSW); 23, 3Ƥ, 13.5 km W of Nungarin on Rt 50, 31°6.928’S 117°56.697’E, 300 m, 16 November 1999, RT Schuh, G Cassis and R Silveira, locality code WA99-L3-H8 (AM); 2Ƥ 28km S of Menzies (3.5km E of Highway, 500 m, 29°55.149’S 121°09.085’E, 25 October 1996, RT Schuh and G Cassis, locality code WA96-L18, ex Thryptomene aspera E.Pritz. subs. aspera (Perth05095093) (AM).

Diagnosis. Thaumastocoris petilus is readily distinguished from all other species of Thaumastocoris by the following characters: slender body, with costal margins subparallel; weakly pedicellate eyes ( Figure 7 C,D); subcontiguous forecoxae, with prosternum bipartite ( Figure 15 B); propleuron strongly expanded ( Figure 15 B); pygophoral lock broadly triangulate; paramere subquadrate ( Figure 19 C). The species can be distinguished from T. hackeri , another species with closely inserted forecoxae, by its weakly pedicellate eyes (cf. Figure 4 C,D). The eyes of T. hackeri are strongly pedicellate and its forecoxae are separated by approximately half the width of the forecoxae. Furthermore, the abdomen of T. hackeri is expanded, and is visible in dorsal view beyond the costal margins.

Redescription. Submacropterous. Male 2.37–2.77 length, 0.74–0.86 width; female 2.45–2.88 length, 0.81– 0.92 width; females are slightly larger in size than males. Colouration. Dorsum straw-coloured with contrasting cream markings. Head: mostly straw-coloured; vertex more yellow; genae with light brown stripe. Antennae: mostly yellowish brown; AII with subapical margin dark brown to fuscous; subapical half of AIII and most of AIV dark brown to fuscous ( Figure 7 C,D). Labium: LI–LIII straw-coloured, LIV light brown. Pronotum: mostly strawcoloured, pronotal disc cream medially. Thoracic pleura and sterna: mostly golden yellow, propleura becoming darker dorsally; prosternum and midline of metasternum cream-coloured. Scutellum : uniformly golden

yellow. Hemelytra: mostly cream-coloured; membrane lighter, medially infused with light brown ( Figure 7 C,D). Legs: uniformly straw-coloured, with second tarsomere dark brown. Abdomen: uniformly golden yellow, slightly darker medially. Texture. Dorsum moderately polished, with scattered shallow to deep setose punctures. Head: vertex impunctate; epicranial suture with shallow irregular punctures; mandibular plates irregularly punctate, denser posteriorly, punctures shallow ( Figure 15 A). Pronotum: callosite region sparsely punctate, punctures shallow, denser along midline and anterolateral angles; disc densely and regularly punctate, punctures deep, posterolateral angles impunctate ( Figure 15 B). Thoracic pleura and sterna: propleuron with irregular distribution of shallow punctures apically, moderately dense and uniform distribution of punctures posteriorly; thoracic sterna mostly with sparse and irregular distribution of punctures. Scutellum : densely and regularly punctate, punctures moderately deep, midline polished posteriorly. Hemelytra: clavus and corium with uniform and moderate distribution of deep punctures, as on pronotal disc ( Figure 7 C,D). Abdomen: impunctate, moderately polished. Vestiture. Dorsum with uniform distribution of setose punctures, setae short, straw-coloured. Venter with uniform distribution of fine, straw-coloured, erect setae; mesosternum with irregular distribution of setae medially, sparse laterally. Antennae: with uniform distribution of short erect setae; AIII–AIV with same setae on lateral margins, otherwise bare ( Figure 15 C). Male genitalia: pygophore clothed in fine setae, more elongate and denser near genital opening; pygophoral lock with denser setae medially; paramere evenly beset with setae, sparse apically ( Figure 19 C). Structure. Head: mandibular plates elongate, surpassing clypeus by less than clypeal length, contiguous medially, weak to moderately flared anteriorly, weakly concave dorsally with lateral margins parallel to weakly flared ( Figure 15 A); bucculae, strongly arcuate ( Figure 15 B). Eyes: weakly pedicellate ( Figure 7 C,D; 15A,D). Antennae: AI and AII cylindrical; AIII and AIV dorsoventrally flattened; AII distally expanded; AIV moderately lanceolate ( Figure 15 C). Labium: short, reaching anterior margin of prosternum ( Figure 15 B). Pronotum: weakly constricted medially; callosite region and disc subequal in length, disc broader; callosite region depressed along midline; anterolateral angles weakly tuberculate; lateral margin of disc weakly arcuate ( Figure 15 D). Thoracic pleura and sterna: propleuron strongly ventrally expanded, approaching midline of body ( Figure 15 B); other pleura weakly ventrally expanded; prosternum bipartite, shieldlike posteriorly, subcordiform ( Figure 15 B). Hemelytra: at rest extending to abdominal TIX, medial margin of corium convex, apex of corium at membrane moderately narrowed, medial margin less than 45° to costal margin ( Figure 7 C,D). Legs: forecoxae subcontiguous, strongly incrassate ( Figure 15 B); fossula spongiosa elongate, reaching distal margin of second tarsomere; 6–9 foretibial teeth, 5–8 midtibial teeth, 0– 2 hindtibial teeth. Male Genitalia: pygophoral lock broadly triangulate, weakly excavate medially; paramere subquadrate ( Figure 19 C).

Measurements. See Table 2.

Distribution. Thaumastocoris petilus is broadly distributed in temperate Australia, with one record from central Australia ( Figure 21 A). Overall, this species appears to be adapted to drier conditions ( Cassis et al, 1999).

Host plants. Thaumastocoris petilus has been collected from six host species representing three genera from the family Myrtaceae . It is most commonly recorded from species of Melaleuca ( Table 3 ). It is a narrow species, and it is cryptozoic on the thin, needle-like leaves of their Melaleuca hosts ( Figure 2A ).

Remarks. Cassis et al. (1999) were reluctant to assign new material to this species, urging caution until the type was examined. We have examined the holotype of Thaumastocoris petilus and it is in very poor condition. There is no doubt that it is conspecific with the material examined in this work, particularly on the basis of the pygophore and paramere. Drake and Slater (1957) did not mention the subcontiguous forecoxal insertion in their description, but it is undoubtedly the most striking character of T. petilus . The range in measurements recorded by Drake and Slater (1957) is similar to the range measured in this study, although specimens from Western Australia are smaller than those collected elsewhere.

Figures

FIGURE 4. Habitus, dorsal view. A and B Thaumastocoris freomooreae. C and D Thaumastocoris hackeri. Scale bar = 1 mm.

FIGURE 7. Habitus, dorsal view. A and B Thaumastocoris peregrinus. C and D Thaumastocoris petilus. Scale bar = 1 mm.

FIGURE 15. Scanning electron micrographs: Thaumastocoris petilus. A 3 head, dorsal view. B 3 head and prosternum, ventral view. C 3 antenna, dorsal view. D 3 head and pronotum, dorsal view. E 3 thorax, lateral view. F 3 Hemelytra, dorsal view. G 3 genitalia, ventral view. H Ƥ genitalia, ventral view. Scale bar = 0.1 mm.

FIGURE 19. Male genitalia. A. Thaumastocoris nadeli, ventral view. B. Thaumastocoris peregrinus, ventral view C. Thaumastocoris petilus, ventral view D. Thaumastocoris roy, ventral view E. Thaumastocoris safordi, ventral view F. Thaumastocoris slateri, ventral view. Scale bar = 0.1 mm.

FIGURE 21. Distribution map. A. Thaumastocoris ohallorani, T. peregrinus and T. petilus B. Thaumastocoris roy, T. safordi and T. slateri.

FIGURE 2. A. Thaumastocoris petilus on Melaleuca glomerata, Palm Valley, Finke Gorge National Park, NT, Australia. (photo C Symonds) B. Thaumastocoris freomooreae mallee habitat, Murray Sunset National Park, Vic, Australia. (photo A Noack).