Arorathrips Bhatti

Nakahara, Sueo & Foottit, Robert G., 2012, Review of Chirothrips and related genera (Thysanoptera: Thripidae) of the Americas, with descriptions of one new genus and four new species, Zootaxa 3251, pp. 1-29 : 4-8

Arorathrips Bhatti

Arorathrips Bhatti 1990: 194 . Type Species: Chirothrips mexicanus Crawford by original designation.

Female. Macropterous. Antennal segment I enlarged, wider than long, at least 2.5 times as wide as base of II; segment II strongly produced laterally and diagonally oriented, normally with an apical sense cone ( Fig. 1 ) or seta, rarely subapical. Head produced anterior of compound eyes, interantennal process conical and not projecting beyond antennal segment I; lateral margin of vertex variously produced between eye and antennal socket; vertex with short, stout setae. Pronotum with many short, stout, spine-like or fine setae; 0, 1 or 2 pairs of developed posteroangular setae. Mesonotum with a pair of median setae far anterior of posterior margin, a pair of setae on or slightly anterior of posterior margin. Mesosternal furcal invaginations separated (although barely so in A. nigriceps ). Metanotum with median pair of short setae far posterior of anterior margin, shorter to subequal with lateral setae on anterior margin; a pair of campaniform sensilla present. Fore wings with costal setae. Abdominal tergites with few to numerous discal setae; posteromarginal flange overlapping posterior part of tergite; abdominal segments IX and X short; sternites with or without posteromarginal lobes; ovipositor short, usually less than 160 µm long.

Male. A pterous or brachypterous. Smaller and usually paler than females. Abdominal sternites III–VII each with small oval to rather large transversely oval or oblong glandular area.

Comments. Sixteen species are assigned here to this genus. Of the four species placed in Arorathrips by Bhatti (1990), A. crassiscelis (zur Strassen), A. mexicanus (Crawford) and A. sensitivus (Andre) are congeneric, but A. mongolicus (zur Strassen) from Mongolia belongs in Chirothrips (Revised Combination) because the mesosternal furcal invaginations are approximated, antennal segment I is not enlarged and segment II is only angulated laterally. The fore tibia of each of these four species has a well developed outer apical process ( Fig. 11 ), which was one of the three anatomical characters Bhatti used to define the genus. However, the fore tibial outer apical process is slightly to moderately developed in several species in other genera, and the process is here considered a specific character. All species retained in Arorathrips as here defined are thus endemic to the New World.

Arorathrips includes three species groups and four miscellaneous species. Members of the mexicanus group, consisting of A. crassiscelis , A. crenulatus (Hood) , A. mexicanus and A. sensitivus , have dermal tuberculate scallops in a row ( Fig. 9 ) or band ( Fig. 10 ) on the anterior part of abdominal tergites, on sternites and on mesonotum of some species; metanotal campaniform sensilla are positioned at midlength or slightly posterior on the notum; and there are five pairs of dorsal setae on abdominal tergites III–VII. Fore tibial outer apical process is as long as, or longer than, first tarsal segment except shorter in A. crenulatus .

Members of the crassus group, consisting of A. crassus (Hood) , A. fulvus (Moulton) , A. oneillae (Watts) and A. spiniceps, (Hood) have minute teeth on the mesonotal sculpture lines ( Fig. 14 ); anterior 1/3 to almost 1/2 of abdominal tergites are differentiated from rest of the tergite by the derm normally being paler and with a series of close-set transverse striae ( Fig. 15 ) which may be finely crenulated or granulose; fore tibial outer apical process is not developed; metanotal campaniform sensilla are near the posterior margin; abdominal tergites III–VII with 5–6 pairs of dorsal setae, except in A. fulvus which has 9–15 pairs of longer setae on the submarginal–lateral area; and sternites without tuberculated scallops or posteromarginal lobes.

Species in the vestis group, consisting of A. dorsalis (Hood) , A. sericatus (Hood) , A. texanus (Andre) , and A.

vestis (Hood) , have numerous setae on the dorsum and venter of the head and body, and the pronotum is weakly or not sculptured. Otherwise, these species are similar anatomically to species in the crassus group. A. childersi , new species, A. lenape (Hood) , A. nigriceps (Hood) and A. xanthius (Hood) cannot be placed in any group.

Arorathrips shares with Konothrips , the other genus in the Western Hemisphere, enlarged antennal segment I, laterally produced segment II and separated mesosternal furcal invaginations. It differs from Konothrips by by having bristle-like or short, stout mesonotal median setae far anterior of the posterior margin and pair of similar setae on or near the posterior margin, or numerous stout setae; well developed posteromarginal flange that overlaps posterior part of abdominal tergites; usually with several costal setae between base and first anterior fringe cilia on fore wing; lateral projection of antennal segment II lacks a distinct membranous gland on apex of process except in A. xanthius ; and abdominal tergal and sternal striations are oriented transversely, reticulated or scalloped and only slightly diagonally oriented on the submargins. Conversely, Konothrips has 4–6 conical or spine-like discal setae in median area of the mesonotum; posteromarginal flange is short and arises from posterior margin of abdominal tergite; fore wing has 0–1 costal seta basal of first anterior fringe cilia; antennal segment II has a distinct membranous gland on apex of lateral process that protrudes over the sense cone; and abdominal tergal and sternal striae are strongly diagonally or longitudinally oriented on the submargins.

Arorathrips childersi sp. n. ( Figs 1–7 )

Female. Macropterous. Head brown, thorax lighter yellowish brown, abdomen lighter than thorax, yellow with grayish brown shading, except segment IX entirely yellow; legs brownish yellow; antennal segment I brown, II brownish yellow basally becoming gradually light yellow distally, III yellowish brown, IV darker yellowish brown than III, V–VIII brown; ocellar crescent red; fore wings yellow with light grayish brown tinge; body and fore wing setae light grayish yellow.

Antenna ( Fig 1 ): Segment I enlarged, diagonally aligned on head, about 2.7 times wider than base of II; segment II strongly produced laterally, lateral margin concave, narrowed at base, anterior margin of projection arched, diagonal dimension from apex of process to base of inner margin about 62 µm, from apex to base of lateral margin about 54 µm; subapical sense cone, about 5 µm long, projecting beyond apex; mediad of sense cone, a short dorsal seta, medially a short dorsal and a ventral setae, short dorsal and ventral setae on inner margin near apex of segment; segment IV about as long as wide; segment VIII shorter than VII; sense cones simple on III and IV, short, about 5 µm long, sense cone on segment V poorly developed, inner sense cone on VI positioned about midlength of segment.

Head ( Fig. 2 ): Prolonged anterior of eyes, longer than wide, lateral margin of vertex anterior of compound eyes about as long as occiput, slightly diverging cephalad to obtuse angle with diagonal anterior margin; compound eyes about 3 times longer than cheeks; 5 short setae on vertex; ocellar setae anterior of fore ocellus by about diameter of ocellus; venter with normal compliment of setae; mouthcone shorter than head, broadly rounded apically.

Thorax: Setae short, bristle-like. Pronotum ( Fig. 3 ): subtrapezoidal, anterior margin considerably shorter than posterior margin, completely sculptured with transverse, scalloped lines; about 50 short, fine, discal setae, about 7 µm long; posterior margin with 20 short, fine setae, longest about 12 µm long, posteroangular setae not developed. Prosternum ( Fig. 6 ) with basantra membranous, weakly textured, setae absent; ferna divided, indistinct, separation from basantra obscure; prospinasternum apparently a narrow transverse band with spina inserted into the mesosternum; membranous area between ferna and prospinasternum with rows of distinct fine granulose-spinulose sculpture. Mesonotum ( Fig. 4 ): sculptured with transverse, scalloped lines, lines lacking minute teeth or not tuberculate; anteromedian campaniform sensilla farther apart than submedian setae; submedian setae far anterior of posterior margin, posterior setae slightly anterior of posterior margin. Mesosternal furca ( Fig. 6 ) with invaginations separated by more than width of mesothoracic coxae. Metanotum ( Fig. 5 ): sculptured almost completely with transverse scalloped lines except few striae longitudinally oriented near lateral margins; submedian setae slightly shorter than lateral setae, far apart by 45 µm, positioned about anterior 1/3 of notum; campaniform sensilla cephalad of and farther apart than median setae. Fore legs: Enlarged, apex of femora not reflected, fore tibiae apically truncate.

Fore wings: Rather straight, tapering to blunt apex; with 14 costal setae, 1–2 basal of anterior fringe cilia, those at midlength about as long as width of wing; 19 anterior fringe cilia, wavy; 5 basal setae in proximal 1/2 and 2 setae in distal 1/2 on fore vein; 5 setae on hindvein; scale with 4 or 5 marginal and 1 discal setae.

Abdomen: Tergites ( Fig 7 ) with sculpture lines scalloped; antecostal ridge not evident; median seta in caudal 1/3 of tergites, shorter than 4 setae laterad to it on tergites II–VII; median campaniform sensilla on II–VIII far anterior of median setae; posteromarginal flange 1/4 to 3/10 as long as tergite, overlapping posterior part of tergite, posterior margin with irregular teeth; tergite IX slightly shorter than X; segment X conical. Pleurotergites with posteromarginal teeth. Sternites with sculpture transverse, reticulated or striae slightly scalloped; posteromargins without lobes or flange; sternite I with 2 anteromedian setae; sternite II with 2 pairs of posteromarginal setae, III–VII with 3 pairs on posterior margin, median pair on VII closer to each other than to B2 setae; ovipositor 153 µm long.

Measurements of holotype: Body length 1.28 mm. Other measurements in µm. Antenna: Total length 215; length, width of segment I 24, 47, II 40, 44; III 37, 25; IV 27, 27; V 30, 24; VI 32, 20; VII 15, 71; VIII 10, 5. Head: length from interantennal process 42, margin anterior of eyes 17 long, compound eye 54 long, occiput 15 long. Pronotum 183 long, 128 wide at anterior margin, 321 wide at posterior margin. Fore wings 776 long, 50 wide at midlength. Abdominal tergite IX 62 long, X 72 long. Setae: tergite IX with B1 setae 101 long, B2 setae 91–99 long; tergite X with B1 setae 117 long.

Male. Unknown.

Type material. Holotype female, U.S.A., Florida, Hendry Co. 5–7 miles south of LaBelle, sticky card in navel orange orchard, 9-III-92, C. C. Childers ( USNM).

Distribution. United States (Florida).

Etymology. Species named in honor of Carl C. Childers, the collector of the specimen.

Comments. Although only a single specimen is available, it is distinct enough that it is unlikely to fall within the variation exhibited by the known species. The postocular setae and part of interocular area of the head could not be observed because of the obstruction caused by the bleeding of the pigmentation from the compound eyes. Also the shape of prospinasternum is difficult to observe.

This species is distinquished from other Arorathrips species as follows: head and body have few setae; vertex of head has five setae; pronotum lacks developed posteroangular setae, and discal setae are short, fine, bristle-like; fore tibia lacks outer distal process; mesonotum lacks tuberculate scallops, and sculpture lines lack minute teeth; metanotum is almost completely sculptured with transverse scalloped lines, median setae are far apart and the campaniform sensilla are anterior to the median setae; abdominal sternites lack posteromarginal lobes or flange.

Figures

FIGURES 1 – 7. Arorathrips childersi sp. n., holotype female. (1) right antenna; (2) head, dorsal aspect; (3) pronotum; (4) mesonotum; (5) metanotum; (6) pro- and mesosterna; (7) abdominal tergite V. Scale bar 100 μm.

FIGURES 8 – 17. Arorathrips species. (8) A. sericat us, abdominal tergite VI (after Hood 1949 a). (9) A. mexicanus, tergite III. (10) A. crenulatus, abdominal tergite. (11) A. crassiscellis, right foreleg (after zur Strassen 1967 a). (12) A. crassus, left antennal segments I to IV (after zur Strassen 1960). (13) A. oneilla e, head, dorsal aspect. (14) A. spiniceps, metanotal sculpture. (15) A. spiniceps, abdominal tergal sculpture. (16) A. spiniceps, praespinasternal area (after Nakahara 1991). (17) A. crenulatus, praespinasternum (after Nakahara 1991).