Symbiotes have been reported by Cowdry (1925C,1926A,1927) and reviewed by Jaschke (1933).

Dinnik and Zumpt (1949) reported on larval integumentary sense organs in relation to those of nymphs and adults as well as of other species.

The "R. simus group" of Zumpt (19424) consists of the species R. simus with two subspecies simus and senegalensis, and of several related species, R. longicoxatus, R. lunulatus, R. tricuspis, R. distinctus, R. p. planus, and R. p. complanatus, R. simpsoni, and R. reichenowi (probably R. zumpti Santos Dias 1950B). These are all Ethiopian Faunal Region species. Zumpt also included the IndoMalayan species R. h. haemaphysaloides and R. h. pilans, but I hesitate so to consider them.

The outstanding diagnostic criterion of the R. simus group is a scutal pattern of few large, fairly deep punctations arranged in about four more or less regular, individually characteristic, longitudinal rows. Among these, interstitial punctations are usually inconspicuous. Adanal shields of males of each species are distinctive. Female scutal patterns may be more variable and those of certain closely related species or subspecies may be difficult to differentiate.

Actually, R. s. sanguineus conforms to this group criterion and might well be considered as a member of the R. simus group. It would then also be much easier to associate the Indo-Malayan species, mentioned above, with this group. Theiler (correspond ence) writes that she agrees with this view. Santos Dias (1952) has considered this group differently.

IDENTIFICATION

Males: This sex is easily recognized and extremely few specimens ever cause doubt as to their identity. The group criterion of four more or less regular rows of rare scutal punctations is always definite, but their distribution and depth are somewhat variable. Although interstitial punctations are usually faint or obsolete, a few specimens show them more distinctly, though

never enough to confuse the picture. Posteromedian and paramedian grooves are absent; rarely they are just barely discernible, but never pronounced. This latter fact is an important distinction between R. s. simus and those specimens of R. s. sanguineus that otherwise closely approximate R. s. simus in appearance. The scutum is arched and usually shiny black, less commonly reddish brown or reddish yellow, with definite, deep lateral grooves and clear festoons. The central festoon may protrude with engorge ment. A hump of coxa I projecting dorsally frequently is large enough to resemble a pointed projection, but closer inspection indicates its bluntness. Ventrally, the shape of the adanal shields, with their rounded external and internal margins, is usually characteristic; but in some specimens, in which they are abnormally narrow and with a deeply concave inner margin, they approach the sickleshape of the subspecies senegalensis. Size is extremely variable, running from minute (1.9 mm. long rarely) to well over 5.0 mm. long.

Female: The outline of the black (rarely reddish) scutum is subcircular with a broadly rounded, slightly sinuous posterior margin; the length width ratio is approximately equal or slightly wider than long. Punctations are normally rare but may be some what heavier and more distinct than in the male. Interstitial punctations are rare and inconspicuous, or absent; rarely they are somewhat pronounced and slightly confuse the typical picture of this species. Lateral grooves are of variable distinctness and length; frequently they are extended posteriorly by a few punctations; in some individuals they are much reduced. The converging and thence diverging cervical grooves usually clearly extend to or almost to the posterior margin, but may be obsolete on the posterior third of the scutum. Lateral fields usually contain two or three punctations; eyes are flat. Size is variable with tremendously engorged individuals reaching 15.0 mm. in length.

Most females are easily keyed but those with reduced lateral grooves are apt to be confusing. Females of the subspecies simus and senegalensis are quite similar.

The nymph and larva have been described and illustrated by Theiler (1943).

Figures 305 and 306, o, dorsal and ventral views Figures 307 and 308, g, dorsal and ventral views

PLATE LXXXV

- 753

Specimens in the Sudan Government collection noted above were collected by H. H. King in 1910 and 1911. They had been identified as R. simus and as R. falcatus.

DISTRIBUTION IN THE SUDAN

Bahr El Ghazal: lo, lọ from buffalo, Guar, Galual Nyang Forest, 8 June 1953, P. J. Henshaw legit. lo, and 508 and 18 gọ

*Collected with 300 and 1o R. simus simus. This is the only col lection seen from anywhere In Africa in which typical specimens of both subspecies have been found on a single host. The host was obviously a migrant.

**For comment, see BIOLOGY below.

from two warthogs, same locality as above, 7 June 1953, and 8 January 1954, collected by E. T. M. Reid and P. Blasdale. Nu merous other specimens collected in the same area in July by the same persons, but without host data. 1o, 200, recently molted clinging to grass (with Dermacentor rhinocerinus), 25 miles west of Yirol, 23 November 1954, E. T. M. Reid legit. 1000 and 2209 (some of which intergrade with R. simus simus) (cf. IDENTIFICATION below), from elephant near Kenisa, May 1953, E. T. M. Reid legit. Sudan Government collections contain other Kenisa area specimens from elephants, collected in 1911, which show similar intergrada tion with R. s. simus (cf. REMARKS below). Mr. Reid has sent me numerous specimens from three elephants shot near Yirol; these are typical R. s. simus.

DISTRIBUTION

R. simus senegalensis is a West and Central African tick with scattered loci in more humid areas of East Africa as far south as northern Nyasaland.

Simpson

WEST AFRICA: NIGERIA (Unsworth 1952. As R. simus: 1912A, p. 325; det. by Nuttall and Warburton as R. simus falcatus; see p. As R. simus longoides: Unsworth 1949, Mettam 1950, Gambles 1951). FRENCH WEST AFRICA (Koch 1844. Rousselot 1951, 1953B. As R. simus longoides: Villiers 1955). SIERRA LEONE, IVORY COAST, GOLD COAST, TOGO (Zumpt 1943A*). PORTUGESE GUINEA (Tendeiro 1952B,C,1953,1954).

CENTRAL AFRICA: CAMEROONS (Zumpt 1943A*. Rageau 1951,1953A, B). FRENCH EQUATORIAL AFRICA (Zumpt 1943A*. Rousselot 1951). BELGIAN CONGO and RUANDA URUNDI (?As R. simus shipleyi: Bequaert 1930B,1931. Zumpt 1943A*. Rousselot 19538. Theiler and Robinson 1954. Van Vaerenbergh 1954. See HOSTS below).

EAST AFRICA: SUDAN (In part as R. simus and as R. falcatus: King 1926. Hoogstraal 1954B,C). UGANDA and TANGANYIKA (Hoogstraal 1954C. J. B. Walker, unpublished; see HOSTS below).

*All Zumpt (1943A) records are under R. simus longoides subsp. nov. which Zumpt (1950A) later synonymized under R. simus senegalensis.