Post-larval Instars Research Articles

Larvae of Leptus (Acarina: Erythraeidae), free-living or ectoparasitic on arachnids and lower insects of Australia and Papua New Guinea, with descriptions of reared post-larval instars

Abstract Leptus larvae (Acarina: Erythraeidae) of Australia and New Guinea, collected either free-living or ectoparasitic on Arachnida or lower Insecta, are comprehensively reviewed. For Australia the following new species are described. From Scorpionida L. barmeedius , L. baudini , L. carduus , L. hitchcocki , L. korematus , L. pistoris , L. smithi and L. urodaci ; from Araneae L. minno ; from Insecta L. norrisi (Archaeognatha) L. flindersi (Blattodea) L. cheesmanae (Phasmatodea) L. bankensis , L. calcar , L. cultellus , L. foliatus , L. lighti , L. pincheni and L. tindalei (Orthoptera, Acridoidea) L. batjallus , L. clavatus , L. clelandi , L. elderi , L. fisheri (Hemiptera) L. grossi and L. puniceus (free-living only); some of the preceding species were also captured free-living. From Papua New Guinea the following new species are described L. calcar (Acridoidea) L. cheesmanae (Orthoptera: «cricket») (both of these species also from Australia) L. lorarius , L. scutellatus and L. triacanthus (free-living). Additional host and other records are given for previously described species, originally described as ectoparasites of Insecta: from Australia L. bathypogonus Womersley (Acridoidea) L. cerambycius Southcott (free-living) L. charon Southcott (Araneae, Scorpionida) L. faini Southcott (Araneae) L. orthrius Southcott (Hemiptera); from Papua New Guinea L. draco Southcott (Odonata, Acridoidea, Tettiginioidea, Phasmatodea, Hemiptera). Protonymphs are described of L. barmeedius , L. baudini , L. calcar , L. charon , L. flindersi , L. orthrius and L. smithi . Deutonymphs are described of L. calcar , L. charon , L. flindersi and L. smithi . A key is provided for the known larvae, protonymphs and deutonymphs of Leptus of Australia and Papua New Guinea. Teratological abnormalities are recorded for L. cultellus , L. fisheri , L. minno and L. urodaci.

Larvae of Leptus (Acarina: Erythraeidae), free-living or ectoparasitic on arachnids and lower insects of Australia and Papua New Guinea, with descriptions of reared post-larval instars

Leptus larvae (Acarina: Erythraeidae) of Australia and New Guinea, collected either free-living or ectoparasitic on Arachnida or lower Insecta, are comprehensively reviewed. For Australia the following new species are described. From Scorpionida L. barmeedius, L. baudini, L. carduus, L. hitchcocki, L. korematus, L. pistoris, L. smithi and L. urodaci; from Araneae L. minno; from InsectaL. norrisi (Archaeognatha) L. flindersi (Blattodea) L. cheesmanae (Phasmatodea) L. bankensis,L. calcar , L. cultellus, L. foliatus, L. lighti, L. pincheni and L. tindalei (Orthoptera, Acridoidea) L. batjallus, L. clavatus, L. clelandi, L. elderi, L. fisheri (Hemiptera) L. grossi and L. puniceus (free-living only); some of the preceding species were also captured free-living. From Papua New Guinea the following new species are described L. calcar (Acridoidea) L. cheesmanae (Orthoptera: «cricket») (both of these species also from Australia) L. lorarius, L. scutellatus andL. triacanthus (free-living). Additional host and other records are given for previously described species, originally described as ectoparasites of Insecta: from Australia L. bathypogonus Womersley (Acridoidea) L. cerambycius Southcott (free-living) L. charon Southcott (Araneae, Scorpionida) L. faini Southcott (Araneae) L. orthrius Southcott (Hemiptera); from Papua New Guinea L. draco Southcott (Odonata, Acridoidea, Tettiginioidea, Phasmatodea, Hemiptera). Protonymphs are described of L. barmeedius, L. baudini, L. calcar, L. charon, L. flindersi, L. orthrius and L. smithi. Deutonymphs are described of L. calcar,L. charon , L. flindersi and L. smithi. A key is provided for the known larvae, protonymphs and deutonymphs of Leptus of Australia and Papua New Guinea. Teratological abnormalities are recorded for L. cultellus, L. fisheri, L. minno and L. urodaci.

<span>Notes on the development of </span><span class="hitHilite">Afronothrus</span> <span class="hitHilite">incisivus</span><span> (Acari: Oribatida) with new distribution records from Asia and Australia</span>

Afronothrus is a distinctive genus of oribatid mites in the family Trhypochthoniidae. The type species, A. incisivus Wallwork, was previously known from Africa, the neotropics, and various islands; our new records from China (Guangdong Province), Singapore and Australia (Queensland) show it to be circumglobal in warm latitudes. The ontogeny of this species is described and partially illustrated. Many aspects of development are intermediate in nature between those of other Trhypochthoniidae and the genus Trhypochthoniellus (Trhypochthoniellidae). All postlarval instars possess a sac-like cuticular structure invaginating from the bothridium, which was previously unknown.

Behavioral interactions of postlarval and fifth instar lobsters (Homarus americanus) in a simulated cobble environment

Behavioral interactions among newly settled postlarval and fifth instar lobsters in a simulated cobble environment were quantified. Seven behavioral categories were identified and the proportion of time spent in each was evaluated. Transition matrices for three general behavior categories were evaluated for the postlarval and fifth instar. Postlarval and fifth instar lobsters displayed different behavioral patterns. Postlarvae spent a large proportion of time walking on the sand substrate and excavating shelters, whereas fifth instar lobsters spent the majority of time excavating and sitting in shelters. Agonistic interactions between early benthic stage lobsters were similar to those described for older juvenile and adult lobsters. Dominance hierarchies, burrow invasion and eviction of subdominant individuals were observed in both the postlarval and fifth instar.

The life cycle and parasitism of the European grasshopper mite Eutrombidium trigonum (Hermann 1804) (Prostigmata: Parasitengonae: Microthrombidiidae), a potential agent for biological control of grasshoppers (Saltatoria)

The European grasshopper mite Eutrombidium trigonum (Hermann) lives concealed in the soil in relatively warm and xeric biotopes. The eggs and spermatophores display a moderate drought resistence. The adults, during mating and larvae leave the soil and are to be found on the soil surface. The host range of the parasitic larva is restricted to Saltatoria. The larval growth is much greater than that of other instars of E. trigonum; however, no damage or other effects on the hosts were obvious and usually the hosts survived parasitism. The active post-larval instars of E. trigonum are predatory and feed exclusively on the eggs of Acrididae. The life cycle of E. trigonum is uni- to semi-voltine and is synchronized by an obligatory diapause of the adult instar before reproduction.

Estimation of Recent Growth of Field-Caught Postlarval American Lobsters,Homarus americanus, from RNA:DNA Ratios

We developed a growth model for the postlarvae of the American lobster, Homarus americanus, using the relationship of RNA:DNA ratios, temperature, and growth rates during postmolt through early pre-molt of laboratory-reared postlarval lobsters. The model was used to estimate individual growth rates of 385 postlarval lobsters in molt stages C and D0, collected at two sites in Block Island Sound over three years, 1988–90. The mean growth rates of postlarvae collected in June 1989 and 1990 (0.57 ± 0.19 and 0.54 ± 0.18 mg protein∙d−1) were significantly higher than those collected in July (0.39 ± 0.17 and 0.43 ± 0.18 mg protein∙d−1). Changes in sea surface temperatures of zooplankton biomass did not account for the seasonal difference in growth rates, nor was there correlation between the biweekly mean growth rates and postlarval densities. The incidence of poorly nourished postlarval lobsters (individuals with growth rates < 0.22 mg protein∙d−1) was less than 10% of the total samples in each year. We found no evidence that food limitation, resulting in starvation or prolonged duration of the postlarval instar, was a significant factor contributing to the observed interannual variability of postlarval densities.

Changes in nucleic acids over the molt cycle in relation to food availability and temperature in Homarus americanus postlarvae

Postlarval lobsters Homarus americanus Milne Edwards hatched from three females collected in 1989 from Block Island Sound, Rhode Island were reared individually in the laboratory under nine treatment combinations of temperature (15, 18 and 21°C) and feeding (starved, low ration and full ration). Total RNA, DNA (mgind.-1), RNA:DNA ratios and molt stage were determined for individuals sampled at daily intervals. Postlarval lobsters had high resistance to starvation. A majority of the lobsters survive 12 d of food deprivation, with some surviving up to 24–29 d. During starvation, cell biomass (estimated from protein:DNA) decreased to a minumum size, whereas cell number (based on total DNA) was generally conserved. The molt cycle was arrested at molt stage C in the starved postalrvae. Instar duration was inversely related to temperature. However, the duration of the postlarval instar did not differ between the low and full ration treatments. Uncoupling of cell growth and the molt cycle was evident in the full and low ration treatments. In the full ration treatments, the postmolt through early premolt was characterized by a rapid increase in total RNA and DNA. Maximum cell biomass was attained by molt stage C or D0. In the low ration treatments, total RNA and DNA were less than those in the full ration treatments and the maximum cell biomass was attained only at molt stage D2-3. Notably, different feeding regimes resulted in different patterns in RNA:DNA ratios over the molt cycle during the postlarval instar. RNA:DNA ratio was a sensitive indicator of recent (2 to 3 d) food deprivation. However, this ratio was positively related to the level of feeding only at molt stages C to D1 and was inversely related to temperature regime. These results indicate that the use of RNA:DNA ratios to estimate the relative nutritional state of postlarval tobsters must be qualified with respect to the period of the molt cycle and the temperature regime.

Revision of the larvae of Leptus Latreille (Acarina: Erythraeidae) of Europe and North America, with descriptions of post-larval instars

The larvae of Leptus Latreille, 1796 (Acarina: Erythraeidae) of Europe and North America are comprehensively revised. Of those described since 1900 a total of 34 species is considered recognizable and capable of being keyed; no species described before 1900 is considered recognizable. The nominal type of the genus, Acarus phalangii de Geer, 1778 is rejected as an illegitimate name. Eighteen European and 17 North American species are described and keyed, of which 17 are new to science. One new subspecies from North America, of a species previously known from Europe, is described and keyed. Standard metric data are given for each species or subspecies from available specimens (except two North American species, L. ariel Southcott and L. clarki Southcott, recently described elsewhere; for these last-named two additional metric data are given). Larvae have been recorded from April to September, with the greatest number found being for July and August. Protonymphs are described for two North American species (L. ghiradellae sp. nov. and L. welbourni sp. nov.), and deutonymphs for two North American species (L. calix sp. nov. and L. ghiradellae). Keys are given to separate the reared protonymphs, and three described deutonymphs (the two preceding and the European L. galerucae Feider). Data on the duration of the protonymphal instar suggest that in North America and Europe there are two modes: one lasting 3–4 weeks, the other 5–7 months. Developmental abnormalities are recorded systematically.

TWO NEW SPECIES OF ERYTHRAEIDAE (ACARI: PROSTIGMATA) ASSOCIATED WITH THE SPRUCE BUDWORM, CHORISTONEURA FUMIFERANA (CLEMENS) (LEPIDOPTERA: TORTRICIDAE), IN MAINE

AbstractTwo new species of the mite family Erythraeidae (Acari: Prostigmata: Parasitengona) found associated with the spruce budworm, Choristoneura fumiferana (Clemens) (Lepidoptera: Tortricidae), in Maine are described. Larvae of Leptus treati sp.nov. parasitize spruce budworm adults; L. treati is the first member of the genus to have both larval and postlarval instars described. Adults of Balaustium kendalli sp.nov. prey on spruce budworm eggs; B. kendalli is only the second member of the genus to have both larval and postlarval instars described.

Molt increment, molt cycle duration, and tissue growth in Palaemonetes pugio Holthuis larvae

Growth in larvae of the shrimp Palaemonetes pugio Holthuis was examined to find if growth of the dorsal carapace (molt increment, MI), epidermis and muscle growth was dependent on the molt cycle duration (MCD). The dorsal carapace grew by 9–25 % at each molt through eight larval and one postlarval instars. Variation in carapace length (CL) decreased with larval age. Larvae reared individually through the first three instars demonstrated different trends in molt increment for each instar. Although half of the larvae underwent a continuous increase or decrease in MI (compared to the preceding MI), other larvae demonstrated an increase followed by a decrease, or vice versa, in MI. There was an inverse relationship between CL and MI for instar I, but not for instar II and III larvae. Growth of the epidermis and muscle was studied in instar II larvae. The epidermis in the posterior dorsal carapace increased in cell density during the 1st day of the molt cycle. At ecdysis to instar III, the cell density returned to a level equivalent to that of Day 1, instar II. The increase in cell density during instar II was proportional to the increase in area of the cuticle at ecdysis (= square of MI for CL) and could be used to predict the size of instar III larvae. The lateral thoraco-abdominal extensor muscle grew in length and width throughout the larval period and muscle size was highly correlated with CL. The MCD was inversely related to temperature in larvae reared at 15, 20, 25 or 30 °C. The MI was greatest at 20 and 25 °C. The MI, epidermal growth, and muscle growth, however, were independent of MCD. Exposure to 20-hydroxyecdysone (20HE) significantly shortened the intermolt period (A-C) in instar II larvae but did not decrease the MCD. There was no difference in MI or growth of the epidermis or muscle in 20HE-treated larvae. The results show that, during the first three larval instars, MI is independent of MCD and that tissue growth is not affected by the duration of the molt cycle. Growth and molting appear to be regulated in a coordinated but separate manner.

Overriding of the Molt-Inducing Stimulus of Multiple Limb Autotomy in the Mud Crab Rhithropanopeus Harrisii by Parasitization with a Rhizocephalan

Specimens of the mud crab Rhithropanopeus harrisii underwent ecdysis within 16 days following autotomy of six walking limbs from each, compared to a mean of 40 days for untreated controls. The second ecdysis following autotomy also occurred sooner than that of controls of equivalent size. Crabs parasitized by the rhizocephalan parasitic castrator Loxothylacus panopei did not undergo ecdysis during the duration of this investigation (140 days) whether autotomized or not. Parasitized crabs from which walking legs had been autotomized in the laboratory did not form limb regenerates. However, two parasitized crabs that had been collected from the field bore large regenerates that may have developed before the rhizocephalan-induced anecdysis. It appears that sacculinids prevent ecdysis of their hosts even after proecdysis has been initiated. In a pattern typical of sacculinid-host associations, prevalence of the castrator decreased with increasing host size. In 1956, Bliss noted that five specimens of the Bermuda land crab Gecarcinus lateralis (Freminville) missing six to eight limbs molted sooner than controls, three within two to four months, the other two, within six months. Similar observations were systematized and the advantages of multiple limb autotomy (>4 for G. lateralis) over eyestalk ablation in initiating proecdysis in five species of decapod crustaceans were described in several publications from this laboratory (Skinner and Graham, 1970, 1972; Holland and Skinner, 1976). Subsequently, others have found multiple autotomy an effective trigger of precocious molts in more than a dozen additional species (reviewed in Skinner, 1985). The following summary taken from that review is based on studies of G. lateralis. Within a few days following closure of the wound, a regenerating limb bud forms at the autotomy plane. Regenerates do not grow further while the animal is in anecdysis, but grow rapidly during proecdysis (Bliss, 1960). If a regenerate' is autotomized before a critical period, probably DI, growth of other regenerates ceases and the proecdysial period is extended until a second regenerate is produced. If a regenerate is autotomized following the initiation of D1, however, the sequence of proecdysial events continues without interruption and culminates in ecdysis without the autotomized regenerate having been replaced (Skinner and Graham, 1972; Holl nd and Skinner, 1976). Specimens of Uca pugilator and Uca pugnax are among the species of Crustacea in which multiple limb autotomy induces a precocious molt (Skinner and Graham, 1972); an interruption of proecdysis by limb autotomy can occur during stage DI in U. pugilator(Hopkins, 1982). In megalopae and early postlarval instars of Rhithropanopeus harrisii which have a very brief anecdysis (5-8 days), limb autotomy either (1) lengthens the anecdysial period if limb regenerates are formed or (2) shortens the time to ecdysis and regenerates are formed during the subsequent anecdysial period (McConaugha and Costlow, 1980, 1987). Thus1 proecdysis can be induced, arrested, or unaffected depending on the timing of autotomy. Two factors, limb autotomy factor anecdysis (LAFan) and limb autotomy factor proecdysis (LAFpro), have been proposed to explain this dichotomy (Skinner, 1985). LAFan triggers a precocious ecdysis; LAFpro interrupts proecdysis. To summarize, following the loss of >4 limbs during anecdysis, LAFan is produced and, if a threshold titer is reached, the animal enters proecdysis. In contrast, LAFpro is produced following autotomy of a regenerate during early proecdysis; it prolongs the proecdysial period. Once proecdysis has reached a critical stage, probably apolysis which initiates DI, either LAFpro is not released or it is no longer an effective inhibitor.

Structure, function, and development of setae on gill-grooming appendages and associated mouthparts of pinnotherid crabs (Decapoda: Brachyura)

Gills of pinnotherid crabs are groomed by setose epipodite extensions of maxilliped mouthparts. Unlike other Brachyura, some pinnotherid genera lack epipodites on maxilliped 2. Plumodenticulate setae similar to those found in other Crustacea represent the majority of grooming setae found on maxillipeds, maxillae, and maxillules in pinnotherids. Structurally more complex setae with anchor-shaped outgrowths were found in 7 of 19 investigated genera. Plumodenticulate setae with anchors are located on maxillules, maxillae, and maxilliped 1 epipodites of Opisthopus and Dissodactylus, whereas Pinnaxodes and Pinnotherelia carry them also on maxilliped 2 and 3 epipodites. In Anomalifrons and Xenophthalmus, some plumodenticulate setae on maxilliped 3 epipodites are armed with facing unequal recurved hooks, resembling ship chocks, in addition to anchors. Only one pair of chocks occurs per seta. Plumodenticulate grooming setae with long double prongs were found exclusively on four different mouthparts in Mortensenella. Larvae and early postlarval instars of Dissodactylus have a particular type of plumodenticulate grooming seta. These setae cover most of maxilliped 1 epipodite and the distal part of maxilliped 3 epipodite and are clustered on the anteroventral surface of maxillules and medially on maxillae. Some of these plumodenticulate setae develop anchorlike outgrowths between setules and denticules in larger crabs. Anchors appear about 2 months after hatching as a single pair per seta, with more pairs being added proximally to the first pair during consecutive stages. On maxillules, anchor setae become twice as numerous as plumodenticulate setae. On maxilliped 1 epipodites, proportions remain about constant. All anchor setae grow at about the same rate as the appendage on which they originate. Anchor setae on maxilliped 1 epipodites of the largest adult crabs may be over 2 mm long and with up to nine pairs of anchors, whereas those on maxillules are less than 1 mm long, bearing no more than six pairs of anchors. On maxillules, setae with two pairs of anchors remain the most common. On maxilliped 1 epipodites, the most common anchor seta for almost every third instar carries an additional pair of anchors, starting with one pair in instar 6 to seven pairs in instar 27. Anchor setae are also found proximally on the protopodite of maxillae in the smallest juvenile crabs but do not develop anchors until close to maturity. On average, each maxilla carries one anchor seta equipped with a single pair of anchors. Anchor setae were not found on any other appendages or cuticular surfaces. Grooming setae seem to lack chemosensory characteristics. Plumose and denticular outgrowths are interpreted as brushing and combing devices. Anchors, chocks, and double prongs seem particularly suited for dislodging of larger objects or organisms, introduced as larvae by the respiratory current, and also might aid in stripping other plumodenticulate setae of accumulated debris.

New Genus and Species of Erythraeinae (Acari: Erythraeidae) from Mississippi with a Key to the Genera of North American Erythraeidae

A new genus and species of Erythraeinae (Acari: Parasitengona: Erythraeidae) is described from larvae parasitizing Lygus lineolaris (Palisot de Beauvois) (Hemiptera: Miridae) and other arthropods in Mississippi. The active postlarval instars (deutonymph and adult male and female) are described from reared individuals. Bochartia shirleyanneae McDaniel and Bolen and Erythraeus whitcombi Smiley are transferred to the new genus. Paraphanolophus Smiley is transferred from the Smarididae to the Erythraeinae. The terminology of Grandjean is reapplied to the Erythraeidae. A key to the active instars of North American Erythraeidae is provided.

The predatory potential ofPhytoseiulus persimilis, Amblyseius californicus,andMetaseiulus occidentalis(Acarina: Phytoseiidae)

Abstract Feeding proto- or deutonymphal stages of Phytoseiulus persimilis killed about 30% more prey/instar h than respective stages of either Amblyseius californicus or Metaseiulus occidentalis. Reproductive females of P. persimilis killed more than 3 times the number of prey eggs killed by A. californicus and more than 5 times the number killed by M. occidentalis. P. persimilis in the presence of excess prey has the shortest developmental time for active stages (69.3 h), the greatest reproductive longevity (482.4 h), kills the most prey as an immature (13.4 eggs) and as a reproductive adult (503.1 eggs), and consistently kills the greatest number of prey/h as post-larval instars or as reproductive females. An index of predator capability estimates that protonymphal P. persimilis can function at 1 tetranychid egg/74.3 cm2 versus 85.6 cm2 and 66.8 cm2 for A. californicus and M. occidentalis, respectively. Similar results were obtained for predator protonymphs searching for tetranychid protonymphs, with A....

Life cycle of lithobiidae - with a discussion of the r-and K-selection theory.

The life cycle of two lithobiid species (Chilopoda: Lithobiidae) Lithobius mutabilis L. Koch and L. curtipes C.L. Koch in an old beech stand in the Solling is described. In addition to a main egg-laying period lithobiids are able to lay eggs continuously throughout the year. The reproductive potential is small, as only one egg is laid over several days. Most juveniles hatch in the spring and over-winter as L3 or L4 larvae. Epimorph development to attainment of sexual maturity takes nearly 2 years. Adult L. mutablilis live a further 2 years or more, adult L. curtipes about 1 year or more. Total life span is about 5-6 years for L. mutabilis and 4-5 years for L. curtipes. Egg development times and instar durations can be very different for different animals. Mortality is relatively high for eggs and small juveniles and low for post larval instars except the very old animals. A method is presented for construction of a survivorship curve from monthly abundance figures. Due to their slow development, late attainment of reproductive period, long reproductive phase, low reproductive potential, long life span, low mortality of post larval instars except very old animals, lithobiids can be regarded as K-strategists or, better, equilibrium species, among the arthropods. It is argued that the theory of r- and K-selection in its general use is not sufficient for a description of the ecological strategies of animals such as Lithobiomorpha. For lithobiids, variability in development time is a very important means of keeping population size at a constant level. The life cycle of the two lithobiid species is compared with ahat of Geophilomorpha and one henicopid species also occurring in the Solling.

The control of size variation within instars of a crustacean

Two series of Palaemon elegans Rathke were reared in the laboratory under controlled conditions from hatching to the seventeenth instar. Each specimen was maintained separately, and the size variation within the instar sequence analysed. The first five larval instars showed the expected increasing variation, but in the sixth larval and first post-larval instars the variation decreased markedly. This was related to a significant negative correlation between percentage moult increment and premoult body length at the moults preceding these instars. Variation increased again over the first eight or nine post-larval instars, after which a second period of reduction in variation was indicated. The implication is that the prawn can limit size variation in a particular instar by this negative feedback, but that this control mechanism operates only during particular phases of ontogeny.

NymphalSphaerolophusreared from larvalCharletonia(Acarina: Erythraeidae)

Abstract A larva agreeing closely with Charletonia singularis Oudemans was found on a nocutuid moth, Simyra henrici (Grote), light-trapped in Massachusetts. The deutonymph reared from this larva conforms to Sphaerolophus cardinalis (Koch) as redescribed by Franke. Larval cuticle and nymph agree also with larval and postlarval mites reared in Germany by Witte and identified by him as S. cardinalis. Use of the generic name Charletonia rather than Sphaerolophus is considered appropriate for this species as well as for that reared by Ishii in 1953 and for that reared by Rosa and Flechtmann in 1979, but not necessarily for species in which correlation of larval with postlarval instars has not yet been achieved. It appears probable that Charletonia singularis is the larval form of cardinalis.

The Determination of Relative Growth in Crustacea

Relative growth in Crustacea is generally in accordance with the simple allometry rule, y = Bxα. The regulation of growth at each ecdysis is such as to result in the attainment, where possible, of the proportions dictated by this rule. Growth proceeds as a series of phases, each composed of from one to several instars. Within each phase there is simple allometric growth, but both the levels of allometry and the size of the variables often change at the transition between phases. These transition changes may be minimal, but they can be so prominent as to result in an obvious critical moult or metamorphosis. In Brachyura there is a consistent pattern of phases in the later post-larval life, the critical moults separating the final three phases being known as the pre-puberty and puberty moults respectively. There can be polymorphism of the terminal mature phase. The critical moults do not necessarily appear to have fixed positions in the sequence of post-larval instars.

Revision of the larvae of the tribe Callidosomatini (Acarina : Erythraeidae) with observations on post-larval instars

The tribe Callidosomatini (nom. emend. pro Callidosomini Southcott, 1961) is revised for its larval members for the world, including species from Australia, New Guinea, New Zealand, and North and South America. The tribe is left with three genera: Callidosoma Womersley, 1936; Caeculisoma Berlese, 1888; and Momorangia, gen. nov. Callidosoma was previously known from three species from continental Australia. The present paper deals with 10 larval species, including five from Australia: C. wornersleyi Southcott, 1946; C. galtoni, sp. nov.; C. heatherae, sp. nov.; C. dasypodiae (Womersley, 1934); C. tindalei, sp. nov. One species, C. rostratum, sp. nov., is described from New Guinea, and one, C. tiki, sp. nov., from New Zealand. Two species, C. apollo, sp. nov., and C. treati, sp. nov., are described from North America, and one, C. wallaceanum, sp. nov., from South America. The post-larval instars of pupa I (nymphochrysalis or protonymph) and active nymph (deutonymph) of Callidosoma dasypodiae are described from reared material. The protonymph of C. treati is described. Larval Callidosoma were captured either free-living or as ectoparasites upon winged insects: Psylloidea (Homoptera), C. wornersleyi; Lepidoptera, C. apollo, C. dasypodiae, C. tiki, C. tindalei, C. treati, and C. wallaceanum; Diptera, C. tiki; Orthoptera, C. galtoni. C. heatherae and C. rostratum are known only from free-living specimens. For Caeculisoma the only species of larva previously known was C. darwiniense Southcott, 1961. Three further species of larvae are described: C. cooremani, sp. nov., and C sparnoni, sp. nov., from Australia, and C. huxleyi, sp. nov., from New Zealand. Larval Caeculisoma were captured either free-living or as ectoparasites upon winged insects: Orthoptera, C. cooremani; Lepidoptera, C. huxleyi; free-living only, C. sparnoni. Momorangia is founded for two New Zealand species: M. jacksoni, sp. nov., (type species), and M. vallata, sp. nov.; both were taken as ectoparasites upon Homoptera (cicadas), and M. vallata also upon a moth (Lepidoptera).

Growth and Age Determination of the Pacific Edible Crab Cancer magister Dana

Of 2,820 early post-larval unsexed crabs collected by small-meshed trawl in two regions of the Queen Charlotte Islands, 1,175 were measured and the 1st and 2nd post-larval instars were identified as modes at 6.9 and 10.0 mm, respectively. Increments of 5 unsexed moulted crabs, carapace widths 6.80 to 9.96 mm, were from 36.3 to 46.5%. A total of 284 males, from 83 to 186 mm, moulted in crab traps, live-wells, and while at large as tagged specimens; 44 females, from 88 to 145 mm, moulted in traps. Using equations of regression of new carapace width on old width for both sexes and starting at the 2nd instar, average carapace widths were calculated for instars 3 to 15. In the width-frequency distributions of 8,145 crabs, separation of stages was sufficient for identification of age-groups. It is estimated that a year after hatching, males reach stage 5 or 6 (24.2 or 31.1 mm); after 2 years stage 11 or 12 (96.6 or 119.5 mm) is attained; after 3 years stage 13 (146.9 mm); after 4 years most males are in the 14th stage (176.2 mm) and above the British Columbia legal size of 165 mm; and generally after 5 years males are in stage 15 (207.5 mm). Growth of females is similar for 2 years, but afterwards is slower.