Engytatus terminalis ( Gagne )

Polhemus, Dan A., 2018, A new species and new records of Engytatus from the Hawaiian Islands (Heteroptera, Miridae), ZooKeys 796, pp. 97-106 : 102-103

Engytatus terminalis ( Gagne)

Cyrtopeltis terminalis Gagné 1968: 42.

Engytatus terminalis : Schuh 1995: 497.

Material examined.

HAWAIIAN ISLANDS, Oahu: 2 males, 2 females, Koolau Mountains, Mt. Tantalus area, gulch crossing on Kaluawahine Trail, 1500 ft [455 m], 21°20'13"N, 157°48'55"W, 23 May 2017, on Cyrtandra cf. sandwicensis , CL 8528, D. A. Polhemus (BPBM); 3 males, 3 females, Waianae Mountains, Honouliuli Forest Reserve, South Fork of Kaluaa Gulch, 26 April 1970, on Cyrtandra christophersenii [= C. waianaeensis x C. garnotiana ], W. C. Gagné (BPBM); 1 male, 1 female, Koolau Mountains, Honolulu Watershed Forest Reserve, Kului Gulch, 400 m, 31 January 1971, on Cyrtandra cordifolia W. C. Gagné (BPBM).

Ecological notes .

Three species of Hawaiian Engytatus , all of them endemic to Oahu, appear to be exclusively associated with the host-plant genus Cyrtandra in the Gesneriaceae , which contains 58 endemic Hawaiian species, all apparently derived from a single colonizing ancestor ( Wagner et al. 1999, Cronk et al. 2005). Previously, Gagné (1968) speculated that specialization on individual species within this diverse local plant radiation could be a significant species isolating mechanism within Hawaiian Engytatus .

In regard to E. terminalis , Gagné (1968) noted its association with Cyrtandra , but did not specify which species was involved. Bishop Museum specimens collected subsequent to his study bear host-plant labels indicating that they were taken on C. cordifolia Gaudichard. More recently, specimens have been taken on the slopes of Mt. Tantalus, in the Koolau Mountains behind Honolulu, from Cyrtandra cf. sandwicensis . The host-plant determination for these latter specimens is provisional because hybrids between C. sandwicensis (H. Léveillé) H. St. John & Storey and C. grandiflora Gaudichard are known to occur in the Mt. Tantalus area, based on Bishop Museum herbarium specimens, but the large, pubescent leaves of the plants in question are most similar to those of C. sandwicensis . It therefore appears that E. terminalis occurs on at least two Cyrtandra species in the Koolau Mountains. Other Gagné specimens in the Bishop Museum from Kaluaa Gulch, in the Waianae Mountains, are recorded as having been taken on C. christophersenii H. St. John & Storey, which is now considered a hybrid of C. waianaeensis H. St. John & Storey and C. garnotiana Gaudichard ( Wagner et al. 1999). Engytatus terminalis thus utilizes a minimum of three species of Cyrtandra across Oahu as a whole, to some extent invalidating the hypothesis of Gagné (1968) that individual host-plant association would prove to be a species isolating mechanism in the genus.