Six New Species and Additional Records of Chiggers from the Central Pacific (Acarina: Trombiculidae)

Abstract

Described are 6 new species: Schoengastia pobsa from nesting area, seabirds, and European rabbit; Schoengastia saurella from lizards, Cryptoblepharus boutoni and Lepidodactylus lugubris; Microtrombicula nesiota from Sula dactylata; Toritrombicula gygis from Gygis alba; Toritrombicula oceanica from Pluvialis dominica; Toritrombicula thalassa from Nesofregetta albigularis. New host and locality records are given for Blankaartia amersoni, Neoschoengastia atollensis, N. carveri, N. ewingi, N. nr. gallinarum (with description and comments), N. namrui, Neoschoengastoides nr. archaea, Guntherana domrowi, and Guntherana sp. Brennan (1965) identified four species of chiggers in a meager 12 collections from a few seabirds and lizard on four islands of the north central Pacific. Described were Blankaartia amersoni and Guntherana domrowi, and listed were Schoengastia philipi (here revealed to be a new species) and a lone specimen of the peculiar Womersia strandtmanni, a first and only record of its occurrence in the Pacific. This report derives from 111 lots of chiggers collected as that part of the Smithsonian Institution's Pacific Ocean Biological Survey Program to determine species, numbers, host associations, and ecology of all ectoparasites of terrestrial vertebrates in the primary area of interest. General collections were made from 96 host species on 42 islands. Chiggers were identified from 17 hosts plus man (one specimen attached) on 15 islands and three positions at sea, the 18 locations lying within approximately 26? N to 12? S and 167? E to 159? W. Fifteen species including six new are recorded. Sixteen species of chiggers in seven genera are now recognized in the central Pacific. Schoengastia pobsa sp. n. (Fig. 1) Type data: Holotype and 3 paratypes, RML 46987, larvae, from nesting area, McKean Island, 1 May 1966, N. Heryford; 9 paratypes off Psittarostra cantans, Laysan Island, 11 June 1966, Amerson; 4 paratypes off Phaethon rubricauda and 1 off Puffinus nativitatis, Phoenix Island, 15 April 1966, Heryford; 8 paratypes off Oryctolagus cuniculus, Phoenix Island, 26 May 1965, Amerson. Received for publication 18 May 1971. Holotype and some paratypes in the Rocky Mountain Laboratory, other paratypes in the National Museum of Natural History, Bishop Museum, British Museum (Natural History), and Field Museum of Natural History. Diagnosis: S. pobsa and the following species, S. saurella, superficially resemble S. philipi Womersley and Kohls (off skink, Goodenough Island, New Guinea) but are distinguished by 2 mastitarsalae III and dorsal formula 2-10-8-8-6-2, 1 mastitarsala III and 2-8-6-6-4-2 in S. philipi. Body: Ovate, length and width of holotype, unfed, 215 by 110' u. Eyes 2/2, in a plate, diameter of anterior eye, 8 Am. Anus between fourth and fifth rows of ventral setae. Gnathosoma: Mildly punctate. Cheliceral blades with tricuspid cap and a row of 4 to 6 small dorsal teeth. Galeal seta nude. Palpal setae B/N/NNB, rarely the genual with 1 or 2 branches; tarsus with 7 branched setae, a subterminala and a tarsala; tibial claw trifurcate. Scutum: As figured. With deeply convex and mildly sinuous posterior margin and sinuous anterior margin. Sparsely punctate. Sensillae broadobovate, their bases barely posterior to posterolateral setae. AM less than half as long as the subequal AL and PL. Scutal measurements of holotype: AW 49, PW 67, SB 17, ASB 17, PSB 22, AP 20, AM 28, AL 61, PL 62, S 22 X 13. Legs: Moderately to sparsely punctate. Specialized setae as figured: 3 genualae I, genuala II and III, tibiala III, 2 nude mastitarsalae III. Nonspecialized setae heavily to sparsely branched. Coxal III seta anteromediomarginal. Leg index 660 (sum of lengths of legs I to III on one side). Body setae: Dorsal setae arranged 2-10-8-8-6-2; humerals 41 Au, posthumerals 26 to 40 A, becoming smaller posteriorly. Ventral setae 2-2 sternals plus 28 to 32, postanals similar to dorsals. Schoengastia saurella sp. n. Type data: Holotype and 7 paratypes, RML 45540, larvae, off Cryptoblepharus boutoni, Baker Island, 9 July 1963 (this series was referred to