Proceedings ofthe United StatesNational MuseumSMITHSONIAN INSTITUTION . WASHINGTON, D.C. Volume 120 1967 Numlier 3564 A COMPARISON OF AUSTRALASIAN AND AMERICANSPECIMENS OF HEMISQUILLA ENSIGERA (OWEN, 1832)(CRUSTACEA: STOMATOPODA)By William Stephenson^ Drs. Raymond B. Manning, John C. Yaldwyn, and the presentauthor each decided independently and simultaneously that the statusof the AustraUan specimens of Hemisquilla merited reconsideration.Drs. Manning and Yaldwyn graciously consented to this author'sundertaking the main investigation while at the Allan HancockFoundation. Here, Cahfornia material was available mostly fromthe Hancock Foundation collections. Austrahan material has beenobtained from various museums in Austraha (particularly the Aus-trahan Museum, Sydney). Chilean material was Umited to thesmall, complete collection of the Smithsonian Institution; unfor-tunately no recent collections from Chile have been obtained. Dr.John C. Yaldwyn has kindly loaned me the only known New Zealandspecimen.Institutions referred to by abbreviations are: Allan Hancock Foun-dation (AHF); Austrahan Museum, Sydney (AM); Dominion Mu-seum, Welhngton (DM); Scripps Institution of Oceanography (SIO);United States National Museum, Smithsonian Institution (USNM).Measurements throughout are in millimeters. Carapace lengthswere measured with dial cahpers, and other dimensions with the 1 Department of Zoology, University of Queensland, St. Lucia, Brisbane,Australia. 2 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 120 calibrated eyepiece of a stereomicroscope. Both are accurate toca. 0.1 mm.Two considerations are involved: first, whether the material fromAustraUa and New Zealand (i.e. Australasia) is identical with theAmerican, and secondly, what names to apply to the different popu-lations.The author is deeply grateful to Drs. Raymond B. Manning andJohn C. Yaldwyn for helpful suggestions, to Miss May Rees forassistance in computations, and to Mr. I. F. Horton for advice onstatistical matters. Thanks are also due to the directors and cura-tors of Crustacea of the above-mentioned institutions for allowing meto examine their Hemisquilla collections. I also wish to thank thedirectors and curators of Crustacea of institutions not mentioned:Johns Hopkins Marine Laboratory, the Queensland Museum, Bris-bane, and the Tasmanian Museum, Hobart.Names of Chilean MaterialAt the generic level the following names have been employed:Gonodactylus Latreille, 1825 (e.g., by H. M. Edwards, 1837; Nicolet,1849; Miers, 1880; and Bigelow, 1894); Pseudosquilla Dana, 1852(e.g., by Rathbun, 1910; Kemp, 1913) and Hemisouilla Hansen, 1895(e.g., by Schmitt, 1940; and Manning, 1963b).Most workers have used the specific epithets styliferus or stylifera,following H. M. Edwards' (1837) description of Gonodactylus styliferus.Rathbun (1910) showed that G. styliferus H. M. Edwards is a homonymof G. styliferus (Lamarck, 1818), now Pseudosquilla ciliata (Fabricius,1787). She substituted the specific epithet bigelowi, and Gonodactylusstyliferus H. M, Edwards became Pseudosquilla bigelowi Rathbun.This name has been used by a number of American workers for Cali-fornian material (e.g., Hilton, 1915a, 1915b; Buchsbaum and Milne,1960).Meanwhile Australian records have been under P. stylifera (H. M.Edwards) by Whitelegge (1900) and Kemp (1913); and under H.stylifera (H. M. Edwards) (following Schmitt, 1940) by Stephenson(1953, 1954) and Stephenson and McNeill (1955).Manning (1963b) has shown that Gonodactylus ensiger Owen, 1832,from Chile is clearly the Hemisquilla that H. M. Edwards described asG. styliferus. Manning stressed the color similarities between Owen'sdescription and preserved Chilean material, which leaves no doubtthat Hemisqulla ensigera (Owen, 1832) has priority as the name forthe Chilean form. He is also using this name for Australian material(Manning, 1967). NO. 3564 HEMISQUILLA ENSIGERA?STEPHENSON 3DistributionKandall's (1839) Hawaiian record, suggesting continuous pan-Pacific distribution has been shown by Manning (1963b) to have beenbased upon an incorrectly labelled American specimen. EvidentlyAustralasian and American populations are geographically distinct.Past American records show a discontinuous antitropical distri-bution, with distinct Californian and Chilean records, the latterincluding Juan Fernandez (see Schmitt, 1940). One specimen, col-lected by the Allan Hancock Foundation, finks these populations bythe foUowing measurements: juvemle, anterior half of body only,carapace length 6.0 mm, rostral length 1.7 mm, rostral breadth 1.7mm, length eye 3.0 mm, length eyestalk 2.3 mm, length cornea 2.5mm, breadth cornea 2.3 mm, no mandibular palps visible. Otherdata are: Jicarita Is., Panama, dredging east side, 24 fms, shellygravel, coU. W. L. Schmitt, Hancock Galapagos Exped., Velero Sta.240-34, Feb. 20, 1934, USNM 76381. This specimen is obviously aHemisquilla as evidenced by (1) the raptorial claw having a singleterminal tooth and not being swollen basally, (2) the articulationbetween the merus and ischium being terminal, (3) the carapacelacking carinae, and (4) the detailed structure of the narrowest partof the cornea (see p. 10) being identical with that of specimens of H.ensigera. Apart from the unlikely event of the first specimen of anundescribed species being a damaged juvenile, it must belong to H.ensigera.Although only 37 specimens have been available for study, it isevident that the species is common in the Cafifornian region. TheCalifornia Department of Fisheries and Game advise that it is fre-quently caught on rod and line (one was so caught in the author'spresence) and by skin divers. Verbal confirmation has been receivedfrom various unofficial sources. The contrast between apparentabundance and numbers available for study from this region suggeststhe possibility that additional specimens may be recovered fromCentral American waters in futm'e years. Present records certainlyextend the known southern fimit of the Cafifornian population, asevidenced by the foUowing specimens all recently obtained fromMexican waters : (1) cf, east side of North Coronados Is., lower Calif., fishingfine at 100 ft (33 m), Aug. 20, 1949, coU. John L. Perkins, RI 6.2-6(SIO).(2) c^, Ensenada, lower Calif., Feb. 10, 1958, RI 6.2-11 (SIO).(3) 2(f cT, 5.4 mi E Morro Redondo Pt., Cedros Is., 41 fms (74m), trawl, Apr. 20, 1951, Velero Sta. 2030-51 (AHF). 4 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 120(4) (^, Sebastian Vizcaino Bay, lower Calif., coll. Jack Little-page, ace. no. 153 (AHF),(5) 2 cf cf , 3 99, San Cristobal Bay, lower Calif., 41 fms (74 m),trawl, Apr. 27, 1950, Velero Sta. 1949-50 (AHF).(6) cf, 9, 1 juvenile, 27?24' N, 114?40' W, San Cristobal Bay,lower Calif., 40 fms (72 m), Aug. 20, 1960 (1800-1820 hrs.), ottertrawl, 6008B, 123.37, coll. Fred Berry (SIO).(7) cf , Turtle Bay, lower Calif., in purse seine inside bay dur-ing daytime, Stella Maris, coll. Ben Fukuzaki (AHF).(8) 9, 6.25 mi SSW San Hipolito Pt., 36 fms (65 m), trawl,Apr. 29, 1950, Velero Sta. 1952-50 (AHF).The following specimen, kindly loaned by Dr. John C. Yaldwyn,is the first recorded from New Zealand: 9, New Zealand waters,DM reg. no. Z.Cr.l493. Morphological Differences?Initial StudyOnly four possible distinguishing features were noted on preservedspecimens from different areas. In each case there was considerablevariabihty and such overlap between the series that statistical analyseswere deemed necessary.Initially, comparisons were made between Australasian and Ameri-can material. Chilean and Californian collections were pooled forthe following reasons: (1) the single Panamanian specimen tends tobridge the biogeographic gap; (2) probably the northern populationextends in strength beyond the known southern limit as evidenced bythe fact that 15 of the 37 "Cahfornian" specimens have been collectedin recent years in Mexican waters; and (3) the small number ofChilean specimens (9 only) available for study.In each case a quantitative study of a feature was made and groupmeans were computed. In most cases deviations from means ex-hibited by each of the individuals in a group were plotted as frequencydistribution histograms; in other cases raw data were plotted similarly.These histograms sometimes indicate differences in the constitutionof populations from the two areas (figs. 1-3). Histograms showingnormal distributions are not given.Variabilities of populations were computed in terms of standarddeviations divided by means; these again indicate some populationdifferences.Finally, t tests of the significance of differences between groupmeans w^ere carried out (Lacey, 1953, p. 114; Fisher and Yates, 1957).It is appreciated that the applicability of this test is affected by ab-normal frequency distributions; however, the low p values obtained NO. 3564 HEMISQUILLA ENSIGERA?STEPHENSON 5in all relevant cases (p<^0.001) leave no doubt of the significanceof the differences.In certain cases inspection of raw data indicated the possibilityof sexual dimorphism. Means for Australasian males and femalesand for American males and females, respectively, were computedand t tests carried out in "promising" cases within the localitygroupings.In other cases it was suspected that the measured ratios dependedupon specimen size. Using all specimens from a given area, cor-relation coefficients were computed between ratios and carapacelength (i.e., the measure of specimen size) and were tested for sig-nificance (Fisher and Yates, 1957). Regression coefficients werecomputed in several cases.Mandibular palp.?Kemp (1913) noted two-segmented palps inan Australian specimen and from one to three segments in Chileanspecimens. Schmitt (1940) noted three segments on the right andtwo on the left side of a single Southern Californian specimen. 100 6 PROCEEDINGS OF THE NATIONAL MUSEUMInspection of raw data gave no indications of differences betweensizes or sexes of specimens, and analyses were not attempted, Aminor cause of variation is related to loss and regrowth of palps.While many of the palps missing from the specimens may have beenremoved during collection and preservation, the occasional presenceof unusually small palps, typically weakly segmented, suggests thatnatural loss and regrowth can occur. This could reflect varyingenvironmental stresses, apart from any genetical differences.Table 1. ? Comparative data of Australasian and American specimens NO. 3564 HEMISQUILLA ENSIGERA?STEPHENSON 7Figure 1b shows that the Australasian population gives a skewedcurve but the American an approximately normal curve. (This isthe opposite of results shown in figure 1a). Table 1 shows that theAustralasian data vary more than the American. Differences betweenmeans are again significant with p <^ 0.001, and the populations areagain statistically distinct. 5mm Figure 2.?Dimensions of Hemisquilla ensigera: a, rostrum; b, eye, lateral view; c, cornea,anteroventral view (1= length, b= breadth, le= length of eye, Is= length of eyestalk;drawn from male, Queensland Mus. reg. no. W1779).Rostral proportions.?This distinction was suggested initially bycomparison of Australian specimens with Kemp's figure (1913, pi. 7,fig. 84) of a Chilean specimen.All specimens were measured for lengths and breadths of rostrumand carapace lengths. Measuring rostral breadths caused occasionaldiflBculty and basal breadths on the upper surface of the line ofarticulation with the carapace were measured in preference to maxi- 8 PROCEEDINGS OF THE NATIONAL MUSEUMmum breadth (fig. 2a). From these measurements, the ratios L/Brostrum and L carapace/L rostrum were computed.Selected data show a hint of bimodahty in the Australasian data(fig. 3a) and a much less definite hint in the American (fig. 3b). The L/B ROSTRUMA-AUSTRALASIAN DEVIATION FROM MEAN XIOO L/B ROSTRUMB-AMERICAN DEVIATION FROM MEAN XIOOFigure 3.?Frequency distribution histograms showing numbers of Australasian andAmerican specimens with varying deviations from group mean L/B ratios. small "separate" groups with higher deviations are not distinctive asregards sex ratio or size; to simplify analyses, hints of polymorphismin L/B rostrum data were ignored. There are no comparable hints inL carapace/L rostrum data. HEMISQUILLA ENSIGERA?STEPHENSONTable 1 shows that there is equivalent variability in Australasianand American material and that the rostra of American specimens aresignificantly longer than that of the Australasian {p.